Gastrointestinal pathology

Author: Mikael Häggström, M.D.

Appendix

Gross processing

• Measure the length of the appendix.
• ((Note its shape. ))
• Inspect the serosa (color, congestion, adhesions, hemorrhage, exudate etc)
• ((Describe and measure the mesoappendix.))
• Cut off about 1.5 cm from the tip and split it in half long the lumen. Divide the remainder into about 3-5 mm thick transverse slices.
• ((Note the wall thickness))
• Look mainly for:

• Luminal pus or obstruction, including stones.
• Look for any yellow firm areas at the tip, which may be carcinoids. Carcinoids may hide behind obstructions in the tip. If found grossly, submit entire appendix, and ink the surgical margin and submit separately en face
• Wall defects
• Exterior coatings. Note if it contains "stones" or fruit kernels.

• Any tumor. If found:

• Measure the greatest dimension of the tumor
• Look for foci of carcinoma or lymph nodes in the mesoappendiceal fat, which may be lymphatic or perineural invasion

Tissue selection

• Submit:

• At least one half of the tip
• At least one slice from visually inflamed areas.
• ((A transverse slice closest to the base, that is, the surgical cut.))
• ((At least one transverse slice from an intermediate part.))

Particular findings indicating additional sampling include:

• Wall discoloration
• External green-gray-yellow coating
• Suspected wall defects

Submit the entire appendix if:

Excessive mucus.

• There is excessive amounts of mucus, (including a representative section of any free mucus if the eppendix is perforated).
• The surgical report mentions perforation but none is found grossly.
• The surgical report mentions appendicitis but no significant inflammation is found grossly.

Gross report

Example:

((Labeled - appendix. The specimen is received in formalin and consists of a resected)) appendix measuring __ cm in length and __ cm in maximum diameter. The serosa is tan-red {{and hyperemic? smooth / ragged / granular? congested? with a patchy purulent exudate? with adhesions?}} The attached mesoappendix measures __ cm and appears {{ unremarkable? hyperemic? (focally) inflamed?}} On cut sections, the lumen {{is dilated and contains {{ (brown) (semisolid) fecal material? purulent (blood-tinged) exudate? a small amount of blood? a fecalith?}} No perforation is identified. ((Representative sections are submitted for microscopic examination in __ cassette(s).))

  See also: General notes on gross processing

Microscopic evaluation

Always look for inflammation and malignancy.

Inflammation

Appendix neoplasms by incidence and prognosis.

Main article: Appendicitis

Neutrophilic infiltrates of the wall of the appendix in the correct clinical context confers a diagnosis of appendicitis.

Malignancy

• Look for cancerous cells (also for specimens with clinical appendicitis).

• Look in particular for carcinoid tumors of the distal tip.
• In the presence of mucus, look for any mucinous neoplasm.

• 

  Appendiceal carcinoid. The arrow points out a cluster of neuroendocrine cells. There are also inflammatory cells consistent with acute appendicitis.

• 

  Low-grade appendiceal mucinous neoplasm: Minimal cytological atypia of the epithelial cells.

• 

  Pie chart of histological types of mucocele of the appendix, with relative incidences

Report

• Description of objective findings.
• Presence or absence of malignancy.

Example, using image at right:

Mucosa with ulceration. ((No atypia in residual mucosa.)) Inflammatory cells in the stroma and all muscle layers, as well as on the serosal surface and adherent adipose tissue. No evidence of malignancy. ((Optionally: No perforation))

For cancers, generally include a synoptic report, such as per College of American Pathologists (CAP) protocols at cap.org/protocols-and-guidelines.

  See also: General notes on reporting

Main page

• Main page of Patholines

Appendicitis

Gross processing

Standard sections if the appendix appears inflamed and there are no signs of malignancy. Describe abnormal signs including:

• 

  Appendicitis with congestion

• 

  Serosa with a patchy purulent exudate.

• 

  Appendicitis, with the lumen containing a blood-tinged purulent exudate.

• 

  Longitudinal section showing a red inflamed mucosa with an irregular luminal surface (in a case of acute suppurative appendicitis).

Further information: Appendix

Microscopic evaluation

• Evaluate depth of the inflammation.
• Look for any perforation of the wall.
• Look for cancerous cells (which may have caused the appendicitis). Further information: Appendix
• (Attempt to specify the type of appendicitis as either of the following:)

Types

Classification of acute appendicitis based on gross pathology and light microscopy characteristics

Pattern	Gross pathology	Light microscopy	Image	Clinical significance
Acute intraluminal inflammation	None visible	Only neutrophils in lumen No ulceration or transmural inflammation		Probably none
Acute mucosal inflammation	None visible	Neutrophils within mucosa, and possibly in submucosa Mucosal ulceration		May be secondary to enteritis.
Suppurative acute appendicitis	May be inapparent. Dull mucosa Congestion of surface vessels Fibropurulent serosal exudate in late cases Dilation of the appendix	Neutrophils in mucosa, submucosa and muscularis propria, potentially transmural. Extensive inflammation Commonly intramural abscesses Possibly vascular thrombosis		Can be presumed to be primary cause of symptoms
Gangrenous/necrotizing appendicitis	Friable wall Purple, green or black color	Transmural inflammation, obliterating normal histological structures Necrotic areas Extensive mucosal ulceration		Will perforate if untreated
Periappendicitis	May be inapparent. Serosa may be congested, dull and exudative	Serosal and subserosal inflammation, no further than outer muscularis propria to be called isolated.		If isolated, probably secondary to other disease
Eosinophilic appendicitis	None visible	>10 eosinophils/mm2 in muscularis propria. No changes conforming to other types of appendicitis		Possibly parasitic, or eosinophilic enteritis.
Chronic appendicitis	Fibrosis	Predominantly mononuclear infiltrate rather than neutrophilic.		Should preferably correlate with long-term or recurrent symptoms.

Further workup

(In acute suppurative appendicitis, still look for any periappendicitis. Also look by the lumen for parasites.)

Microscopy report

Should include, if detected:

• Acute or chronic appendicitis
• Depth of inflammation
• Any abscess and\or perforation
• Necrosis and\or ulceration, at least if transmural

(Classification into one or several types as per table above.)

Example

(Appendix, resection (or appendectomy):) Acute (suppurative) appendicitis (and periappendicitis) with transmural necrosis and perforation.

Gallbladder

Gross processing

Cholecystectomy grossing

• Describe the serosa (smooth and intact versus disrupted, adhesions, inflammation, tumor implants, necrosis, porcelain).
• (Inspect the adventitia (the roughened juxtahepatic surface), where disruptions are generally iatrogenic and optional to report.)
• Cut off the cystic duct margin and submit
• Look for any cystic duct lymph node, describe and submit if present
• Open the gallbladder longitudinally on the serosal surface. Do not open along the adventitia.
• (Estimate the amount of bile.)
• {{Estimate the number and describe gallstones.}}
• Describe the mucosa (such as velvety, granular, trabeculated, and/or with cholesterol stippling)

• 

  Cholesterol stippling (cholesterolosis): yellow streaks of cholesterol deposition, a frequent incidental finding.

• 

  Trabeculated gallbladder.

• 

  Gallbladder polyp

• Look for any gallbladder polyps or tumors. Tumors will usually be hard.
• Open the spiral neck, and look for lesions and gallstones therein
• Cut through the wall, and look for any tumors or Rokitansky-Aschoff sinuses
• Look for gallstones in the container

Gross report

((Labeled - gallbladder. The specimen is received in formalin and consists of a resected)) {{ previously opened? focally disrupted (on the juxtahepatic avdentitial surface only)? edematous?}} gallbladder measuring __ cm in length and __ cm in maximum diameter. The serosa is {{(mottled) tan / pink / red (generally combinations thereof) and}} smooth {{/ with patchy adhesions}} Upon opening, the lumen contains ((__ [[volume in cc/cm3]])) green {{/ brown / blood-tinged / yellow-white and chalky / clear colorless viscid / sludge-like / thick}} bile {{and (approximately) __ (number) / multiple black / brown / green / yellow / tan / white (generally combinations thereof) irregular / multifaceted / spiculated / ovoid / mulberry-like / barrel-like gallstones measuring up to __ cm in greatest dimension.}} The mucosa is green {{/ tan / yellow-red / brown / pink}} and velvety {{/ granular / trabecular with diffuse cholesterol stippling?}} The spiral neck is patent {{/ obstructed by one additional similar gallstone measuring __ cm}}. The wall measures up to __ cm in thickness. {{ Rokitansky-Aschoff sinuses are present within the fundus. There is a __ (color) cystic duct lymph node present measuring __ cm in greatest dimension. }} ((Representative sections are submitted for microscopic examination in __ cassette(s). ))

Rifts on the adventitial side that are consistent with surgical trauma need mentioning only in tumor cases.

Carcinoma

Pathology trainees that find an unsuspected tumor should generally notify a senior before continuing.

• State whether the gallbladder is intact when you received it.
• Ink the surgical margin (adventitial surface).
• Ink the cystic duct margin (lightly) and put in a separate cassette. Notify the lab to have it submitted en face
• Look for any cystic duct lymph nodes. If found, bisect and submit.
• Measure the tumor in greatest dimension and thickness and state where in the gallbladder it is located (fundus, body, etc and whether it is on the peritoneal or hepatic side).
• Measure the margin to the cystic duct resection
• State all other abnormalities including stones, Rokitansky-Aschoff sinuses etc.

Take sections from:

• Cystic duct margin, en face
• Cystic duct lymph node if present
• Sections of tumor, full thickness
• Sections of unaffected gallbladder

Autopsy grossing

Gross pathology of gallbladder carcinoma, with a prominent nodule.

The gallbladder and biliary tract may be cut open from either end:

• Starting from the gallbladder: Cut the gallbladder open and from there dissect the cystic duct and common bile duct through the ampulla of Vater.
• Starting from the duodenum: Identify the ampulla of Vater, possibly by bile flow when squeezing the gallbladder. Dissect the common bile duct, cystic duct and thereafter the gallbladder. If the cystic duct is difficult to find, transverse cuts may be performed at its presumed location.
• In the gallbladder, inspect the contents and the appearance of the wall. Look mainly for signs of carcinoma. Optionally, estimate the volume of bile therein.
• In the biliary tract, look mainly for stones and stenosis.

Further information: Autopsy

Fixation

Generally 10% neutral buffered formalin.

  See also: General notes on fixation

Microscopic evaluation

Look at least at the epithelial lining, for atypia and inflammation (such as edema and inflammatory cells, Further information: cholecystitis ).

• 

  Acute cholecystitis.

• 

  Histopathology of gallbladder carcinoma, with marked nuclear pleomorphism

• 

  Look in the gross report for gallstones, which is generally reported or commented in the microscopy diagnosis as well.

Other findings

• 

  Report a substantial amount of foam cells within lamina propria, conferring a diagnosis of cholesterolosis.

• 

  Liver tissue in the periphery of a gallbladder resection, does not need to be reported.

Report

Example:

(Gallbladder, resection:) Gallbladder with no significant histopathologic changes

In cholecystitis:

(Gallbladder, cholecystectomy:) <<Acute and/or chronic>> cholecystitis. {{Cholelithiasis.}}

For cancers, generally include a synoptic report, such as per College of American Pathologists (CAP) protocols at cap.org/protocols-and-guidelines.

Cholecystitis

Inflammation of the gallbladder:

Gross processing

As per basic Gallbladder.

Microscopic evaluation

Look for signs of acute or chronic cholecystitis. If you find either, keep looking for the other as well, in case it is both acute and chronic.

Findings in acute cholecystisis

Main initial features are edema and hemorrhage.

• Initially often also congestion and fibrin deposition in and around the muscular layer.
• Later often necrosis of the mucosa and and deeper layers, with neutrophils.
• Variable reactive epithelial changes, which may resemble dysplasia.

There may be fresh thrombi within small veins.

• 

  Acute cholecystitis: Lamina propria edema and hemorrhage

• 

  Ulcerated mucosa in acute cholecystitis

• 

  Neutrophils are only sometimes seen and are not necessary for the diagnosis.

• 

  Acute gangrenous cholecystitis: Characterized by necrosis, neutrophils and obliteration of the muscularis layer.

Findings in chronic cholecystitis

Rokitansky-Aschoff sinus.

Typical features are:

• Smooth muscle hypertrophy in the muscularis
• Mild inflammatory infiltrates
• Rokitansky-Aschoff sinuses

Other findings favoring the diagnosis are:

• Granulomas (from ruptured Rokitansky-Aschoff sinuses) strongly favor the diagnosis.
• Hyalinized collagen
• Dystrophic calcification
• Lymphoid aggregates
• Atrophic and/or ulcerated mucosa
• Metaplastic changes, such as gastric or intestinal mucosa

• 

  Gastric metaplasia, seen as pseudostratified epithelium (left), compared to normal (right)

• 

  Eosinophilic cholecystitis

For a general gallbladder screening, see gallbladder.

Lymph nodes

Look for reactive lymphadenopathy or metastasis. Further information: Lymph node

Microscopy report

Report:

• Relevant findings from the evaluation.
• Any cholelithiasis as per the gross report.

Template

On this resource, the following formatting is used for comprehensiveness:

• Minimal depth
• (Moderate depth)
• ((Comprehensive))

Other legend

<< Decision needed between alternatives separated by / signs >>
{{Common findings / In case of findings}}
[[Comments]]
Link to another page

(Gallbladder, cholecystectomy:) <<Acute and/or chronic>> cholecystitis. {{Cholelithiasis.}}

Gallbladder polyp

Fixation

Generally 10% neutral buffered formalin.

Gross processing

Photograph of a 6 mm large hyperplastic polyp of the gallbladder.

As per gallbladder, with addition to submitting the entire polyp unless very large.

Microscopic evaluation

Look for signs of the most common polyp types:

• 

  Gallbladder polyp types by relative incidence.

• 

  Hyperplastic polyp: There is no dysplasia.

Endoscopic gastrointestinal biopsies

Gross processing

• Count the number of fragments. They can be classified as “multiple” at over 5 or 6 specimens. Possibly add “Mixed with luminal material”.
• Preferably stain with eosin if any fragment is smaller than about 0.3 cm
• Biopsies that are thicker than about 3-4 mm generally need to be bisected.

Microscopic examination

(Read the endoscopy report before evaluating (except for polyp biopsies, where it can be presumed that the purpose is to look for any malignancy).)

Example normal reports

Further information in main articles of each location.

Esophagus

(Middle third esophagus, biopsy:) Squamous mucosa without significant histopathologic changes. (Negative for eosinophilic esophagitis.)

Gastroesophageal junction

(GE junction, biopsy:) Squamous and gastric mucosa without significant histopathologic changes. (Negative for intestinalized (Barrett's) mucosa.)

Stomach

(Stomach, biopsy:) Gastric mucosa without significant histopathologic changes. ((Negative for Helicobacter pylori organisms on H&E slide.))

Duodenum

(Small bowel, biopsy:) Small intestinal mucosa without significant histopathologic changes. ((Negative for celiac disease.))

Terminal ileum

(Small bowel, biopsy:) Small intestinal mucosa without significant histopathologic changes. ((Negative for ileitis.))

Colon

(Colon, biopsy:) Colonic mucosa without significant histopathologic changes. ((Negative for colitis.))

Esophagus

Microscopic evaluation

On esophageal biopsies, look at least for esophagitis:

Esophagitis

GE junction with chronic esophagitis, including plasma cells (black arrow), an acute inflammation with neutrophils (white arrow), as well as basal layer hyperplasia (yellow double-headed arrow).

Look for signs of (reflux) esophagitis, mainly:

• Inflammatory cells, especially when intra-epithelial. Neutrophils confer a diagnosis of acute inflammation, while plasma cells, eosinophils and excess T cells confer a diagnosis of chronic inflammation. In eosinophil-predominant inflammation, also evaluate as suspected eosinophilic esophagitis.
• Basal cell hyperplasia exceeding 15 - 20% of the epithelial thickness.
• Stromal papillae reaching upper third of the epithelium.
• Loss of orientation of superficial epithelial cells.
• Ballooned squamous cells

• 

  An intra-epithelial eosinophil (characterized by its bilobed nucleus despite scant visible eosinophilic cytoplasm)

Microscopy report

Example normal report for an esophagus biopsy:

(Middle third esophagus, biopsy:) Squamous mucosa without significant histopathologic changes. ((Negative for eosinophilic esophagitis.))

Example report with signs of reflux:

(Mid esophagus, biopsy:) Squamous mucosa with reactive changes consistent with reflux. ((Negative for eosinophilic esophagitis.))

Eosinophilic esophagitis

Histopathology of eosinophilic esophagitis, showing multiple intraepithelial eosinophils (bilobed cells with eosinophilic cytoplasm on H&E stain), and edema seen as white clearings.

Microscopic diagnosis

An intra-epithelial eosinophil (characterized by its bilobed nucleus despite scant visible eosinophilic cytoplasm)

It is characterized by a prominent eosinophilic infiltrate in the esophagus. Count in at least one high power field of an intraepithelial area where there may be the highest concentration of eosinophils, and count them. Only count eosinophils where you see the nucleus. If you know your high power field (HPF) is about 0.25 mm², diagnose it if you see over 15 intra-epithelial eosinophils per HPF. If your HPF is significantly different, or if you are not sure, diagnose it at over 60 eosinophils/mm². Further information: Evaluation

(Also look for other "minor criteria" associated with eosinophilic esophagitis:

• Extreme basal zone hyperplasia with papillary hyperplasia
• Eosinophils concentrated in the surface epithelium as opposed to the base
• Eosinophilic microabscesses, usually defined as aggregates of at least 4 eosinophils.
• Eosinophil degranulation
• Surface desquamation
• Lamina propria fibrosis.)

Further workup

For cases of eosinophilic esophagitis, also look for any fungal organisms.

Report

• If positive:

• Presence of eosinophilic esophagitis, or findings consistent thereof
• Number of eosinophils per HPF
• (Presence or absence of fungal organisms)

Example in a positive case:

Squamous mucosa with increased intraepithelial eosinophils (up to 80 per high-power field)(, consistent with eosinophilic esophagitis. Negative for fungal organisms (H&E stained slide). See comment.) (Comment: Increased numbers of intraepithelial eosinophils in the squamous mucosa can be found in both reflux esophagitis and eosinophilic esophagitis. Although clinical correlation is recommended, some secondary histologic features favor eosinophilic esophagitis.)

In borderline cases, such as an incidental finding of eosinophils at around 15/HPF:

(Esophagus, biopsy:) Squamous mucosa with increased intraepithelial eosinophils of up to 15/HPF. See comment. ... Comment: There is no evidence of eosinophilic microabscesses. Although this may represent reflux esophagitis, a diagnosis of eosinophilic esophagitis is considered in the correct clinical setting.

Gastroesophageal junction

Microscopic examination

The main findings to look for are:

• Intestinalized mucosa (Barrett's esophagus)
• (Reflux) esophagitis.
• Gastritis. Further information: Stomach
• Esophageal adenocarcinoma

Barrett's esophagus

The main diagnostic sign of Barrett's esophagus is the presence of goblet cells. A true goblet cell should have rounded shape, clear to bluish cytoplasmic mucin, and be randomly scattered. The mucin usually indents the nucleus.

• 

  Histopathology of Barrett's esophagus, showing intestinalized epithelium with goblet cells, as opposed to normal stratified squamous epithelium of the esophagus, and pseudostratified columnar epithelium of the fundus of the stomach. H&E stain.

• 

  In incomplete intestinal metaplasia, there are both foveolar cells and goblet cells, the latter (indicated by arrows) usually having a slightly bluish color compared to the apical cytoplasm of foveolar cells. An occasional but specific sign of goblet cells is crescent shaped nuclei (seen in middle one).

Further information: Barrett's esophagus

Esophagitis

GE junction with chronic esophagitis, including plasma cells (black arrow), an acute inflammation with neutrophils (white arrow), as well as basal layer hyperplasia (yellow double-headed arrow).

Look for signs of (reflux) esophagitis, mainly:

• Inflammatory cells, especially when intra-epithelial. Neutrophils confer a diagnosis of acute inflammation, while plasma cells, eosinophils and excess T cells confer a diagnosis of chronic inflammation. In eosinophil-predominant inflammation, also evaluate as suspected eosinophilic esophagitis.
• Basal cell hyperplasia exceeding 15 - 20% of the epithelial thickness.
• Stromal papillae reaching upper third of the epithelium.
• Loss of orientation of superficial epithelial cells.
• Ballooned squamous cells

• 

  An intra-epithelial eosinophil (characterized by its bilobed nucleus despite scant visible eosinophilic cytoplasm)

Report

(Document the type of mucosa:

• If both gastric and squamous mucosa is present in the same fragment, report as "Gastroesophageal junctional mucosa with..."
• If not, report the presence of squamous and/or gastric mucosa.)

Examples:

(GE junction, biopsy:) Squamous mucosa without significant histopathologic changes. (Negative for gastric mucosa or intestinalized (Barrett's) mucosa.)

(GE junction, biopsy:) Gastroesophageal junctional mucosa with chronic inflammation and reactive changes(, non-specific. Negative for intestinalized (Barrett's) mucosa.)

In case of multiple signs of reflux esophagitis:

(GE junction, biopsy:) Gastroesophageal junctional mucosa with changes consistent with reflux esophagitis. (Negative for intestinalized (Barrett's) mucosa.)

Barrett's esophagus

Microscopic examination

Generally, the main finding to look for in biopsies from the esophagus is intestinalized mucosa (Barret's esophagus), which is defined as the presence of columnar epithelium with goblet cells. A true goblet cell should have rounded shape, clear to bluish cytoplasmic mucin, and be randomly scattered. The mucin usually indents the nucleus.

• 

  Histopathology of Barrett's esophagus, showing intestinalized epithelium with goblet cells, as opposed to normal stratified squamous epithelium of the esophagus, and pseudostratified columnar epithelium of the fundus of the stomach. H&E stain.

• 

  In incomplete Barrett's esophagus, there are both foveolar cells and goblet cells, the latter (indicated by arrows) usually having a slightly bluish color compared to the apical cytoplasm of foveolar cells on H&E stain.

Further workup of intestinalized mucosa

If intestinalized mucosa (Barret's esophagus) is present, look for dysplasia:

• 

  In this case, the area between the stratified and the intestinalized epithelium displays reactive changes from chronic inflammation, but there is no dysplasia.

• 

  Low-grade dysplasia: Simple straight but elongated tubules lined by dysplastic cells.

• 

  Low-grade dysplasia: Elongated tubules crowded together.

• 

  Low-grade dysplasia: Crowded glandular profiles lined by atypical cuboidal cells. These contain basally oriented, enlarged vesicular nuclei and prominent nucleoli.

• 

  Low-grade dysplasia: Pseudostratified epithelium, with hyperchromatic elongated nuclei occupying much of the cells.

• 

  High-grade dysplasia: The cells are cuboidal and the nuclei have lost their normal basal polarity.

• 

  High-grade dysplasia: highly dysplastic cells

• 

  Adenocarcinoma Further information: Esophageal adenocarcinoma

Also perform a screening for esophagitis. Further information: Gastroesophageal junction

Microscopy report

Incomplete Barret's esophagus does not need specific mention:

(GE junction, biopsy:) Gastroesophageal mucosa with chronic inflammation and intestinal metaplasia, consistent with Barrett's esophagus. Negative for dysplasia.

Esophageal adenocarcinoma

Mainly present in endoscopic biopsy of the gastroesophageal junction or distal esophagus.

Microscopic evaluation

In biopsies, classify as either low, moderately or high differentiated.

Well differentiated: >95% gland composition Moderately differentiated 50%-95% gland composition, Poor differentiation is <50% gland composition.

• 

  Histopathology of moderately differentiated esophageal adenocarcinoma

Reporting

Esophagus, biopsy: Invasive adenocarcinoma, moderately differentiated.

Stomach

Microscopic evaluation

Generally screen for:

• 

  Gastric adenomas and adenocarcinomas. Further information: Stomach tumor

• 

  Gastritis, with neutrophils indicating acute gastritis, and plasma cells (pictured) indicating chronic gastritis.

• 

  Reactive gastropathy, which is a triad of:
  - Foveolar hyperplasia (black arrow), generally seen as a tortuosity in the "neck" region of the gastric glands.
  - Scant acute and chronic inflammatory cells (white arrow).
  - Smooth muscle hyperplasia (black oval)

• 

  ((Look for Helicobacter pylori even without signs of gastritis.))

Microscopy report

Example in case of normal findings:

(Gastric, biopsy:) Gastric (oxyntic/antral) mucosa without significant histopathologic changes. (Negative for Helicobacter ((pylori)) organisms on H&E slide.)

Gastric polyp

Microscopic evaluation

Relative incidences of gastric polyps. The remaining 4.8% are mainly constituted by lipomas, GIST, xanthomas and inflammatory pseudopolyps.

• 

  Gastric hyperplastic polyp: Elongated, tortuous, and cystic foveolae separated by edematous and inflamed stroma.

• 

  Gastric hyperplastic polyp, high magnification, showing the edematous and inflamed stroma

• 

  A fundic gland polyp displays cystically dilated glands lined by chief cells and parietal cells, and possibly also mucinous foveolar cells.

• 

  A fundic gland polyp, low magnification.

• 

  A gastric tubular adenoma, high magnification, showing normal gastric gland at left compared to adenoma at right, with crowded, enlarged and hyperchromatic nuclei.

• 

  A gastric tubular adenoma, low magnification, showing hyperchromatic glands.

Fundic gland polyp

Microscopic evaluation

• 

  A fundic gland polyp displays cystically dilated glands lined by chief cells and parietal cells, and possibly also mucinous foveolar cells.

• 

  A fundic gland polyp, low magnification.

Differential diagnosis

• 

  Gastric hyperplastic polyp: Elongated, tortuous, and cystic foveolae separated by edematous and inflamed stroma.

• 

  Gastric hyperplastic polyp, high magnification, showing the edematous and inflamed stroma.

Workup

• 

  Look for dysplasia (center), compared to normal mucosa (at right).

Dysplasia in fundic gland polyp is mainly seen as nuclear enlargement, hyperchromasia, pseudostratification, and loss of cytoplasmic mucin. However, you don't need to spend much effort in the decision, since these patients have an excellent prognosis whether there is dysplasia or not.

Reporting

Generally, keep it short:

(Stomach, excision:) Fundic gland polyp

Gastritis

Author: Mikael Häggström

Inflammation of the stomach. If biopsy is at the esophagus, evaluate as gastroesophageal junction.

Comprehensiveness

On this resource, the following formatting is used for comprehensiveness:

• Minimal depth
• (Moderate depth)
• ((Comprehensive))

Microscopy evaluation

Mucosal plasma cell infiltrate in mild chronic gastritis.

Look for chronic or acute gastritis. If either is present, still look for the other.

Chronic gastritis

• Chronic gastritis

• Presence of plasma cells, lymphocytes, and occasionally lymphoid follicles. Scattered single plasma cells and lymphocytes is normal, and the threshold is subjective, but one definition of chronic gastritis is when seeing chronic inflammation at 4x magnification (as increased dots separating glands) Eosinophils and neutrophils may be present.
• Reduced mucin in the cytoplasm
• Enlargement of nuclei and nucleoi
• Subnuclear vacuolation in antral glands or pits (which is PAS negative)
• Intestinal metaplasia: with partial replacement of the mucosa of the antrum and body with metaplastic goblet cells of intestinal morphology, absorptive cells and Paneth cells.

• 

  Updated Sydney System for visual classification of gastritis.

• 

  Moderate gastritis.

• 

  In intestinal metaplasia (seen at bottom of this antral mucosa), also look for atrophy as pictured.

• 

  Extensive atrophy of oxyntic glands in fundus/corpus causes pseudo-pyloric metaplasia.

When there is at least (mild or) moderate gastritis, especially if relatively superficial, also evaluate as a stomach biopsy for Helicobacter pylori.

Acute gastritis

Histopathology of mild active gastritis, with intraepithelial neutrophils (white arrows) as well as in lamina propria (black arrows).

• Mild acute gastritis:

• Modest edema of lamina propria
• Vascular congestion
• Scattered neutrophils
• Mucosal hemorrhage
• Intact epithelium

• 

  Early acute superficial gastritis: Marked neutrophilic infiltrates appear in the mucous neck region and lamina with a pit micoabscess.

• Moderate to severe acute gastritis:

• Loss of superficial epithelium above the muscularis mucosa
• Hemorrhage
• Variable infiltrate with neutrophils
• Fibrinopurulent luminal exudate
• Nearby epithelium may show regenerative changes

Microscopy report

• Mild and/or chronic gastritis and severity

• (If present, state if positive or negative for Helicobacter pylori organisms.)

Chronic gastritis without neutrophils is preferably also termed "non-active".

Example:

(Stomach, biopsy:) (Gastric antral/oxyntic mucosa with) mild chronic (non-active) gastritis((, non-specific)) (Negative for Helicobacter pylori organisms on H&E slide.)

Main page

• Main page of Patholines

Stomach biopsy for Helicobacter pylori

Helicobacter pylori on HE stain, being curved bacteria in the lumen of a gastric foveola.

Microscopic evaluation

Another H&E stain.

Look for:

• Inflammation, typically a chronic form of gastritis with germinal centers (follicular gastritis), and plasma cells in lamina propria. There should be at least 3 plasma cells facing each other to make a diagnosis of chronic gastritis.
• When there is at least (mild or) moderate gastritis, especially if relatively superficial, go to high magnification and look for Helicobacter pylori-like bacteria in the lumen. They are curved, spirochete-like bacteria, generally in the superficial mucus layer and along microvilli of epithelial cells.

Perform immunohistochemistry for H. pylori in cases of moderate to severe chronic gastritis, or even just one neutrophil within the epithelium, where H. pylori is not seen on H&E stains.

Example report

Stomach, biopsy: Chronic active gastritis. Positive for helicobacter pylori.

Chronic gastritis without H. pylori-like organisms can be described as non-specific:

Mild chronic gastritis, which is non-specific. Negative for H. pylori-like organisms on H&E stain.

Stomach tumor

Microscopic evaluation

Stomach cancer types by relative incidence.

In addition to a general screening (Further information: Stomach ), look for atypical or expanded areas, and attempt top classify by at least the most common forms.

• 

  Gastric adenomas and adenocarcinomas.

Reporting

For cancers, generally include a synoptic report, such as per College of American Pathologists (CAP) protocols at cap.org/protocols-and-guidelines.

Gastric sleeve

Gross processing

• Measure length and maximum diameter, as well as the length of the staple line.
• Inspect the serosal surface.
• Open longitudinally
• Inspect the mucosa.
• Measure the maximum wall thickness.

Tissue selection

2 representative sections, in addition to any visible lesions.

Gross report

Example:

((A. Labeled - ___. The specimen is received in formalin and consists of)) a segment of pink-tan stomach measuring __ cm in length and __ cm in maximum diameter. A staple line (surgical margin) is present which measures __ cm in length. The serosal surface is pink-tan and {{focally ragged with scattered transmural defects}}. A minimal amount of soft, yellow perigastric fat is present. Upon opening, the gastric lumen contains a small amount of bloody mucoid material. The mucosa is red-tan with normal rugae and no gross lesions. The wall measures up to ___ cm in thickness. (Representative sections are submitted for microscopic examination in __ cassettes.)

Microscopic examination

Usual stomach screening. Further information: Stomach

Example reports:

Stomach, partial gastrectomy: Portion of stomach without significant histopathologic findings. (Negative for helicobacter pylori organisms (H&E stain).)

Gastric body, laparoscopic sleeve gastrectomy: Mild chronic gastritis, non specific. (Negative for H. Pylori microorganisms on H&E stained slide.)

Small intestine in celiac disease

Microscopic evaluation

Intraepithelial lymphocytes, in this case still less than <25 IELs/100 enterocytes.

Villous atrophy is another sign of celiac disease. Normal villous:crypt ratio is 3:1. However, this assessment requires proper orientation of biopsies.

The main histologic feature of celiac disease is increased intraepithelial lymphocytes (IELs), with or without villous atrophy of the duodenal mucosa. The number of intraepithelial lymphocytes are classified as follows in the duodenum:

• < 25 IELs/100 enterocytes: Negative for intraepithelial lymphocytosis.
• 25 to 29 IELs/100 enterocytes: borderline
• > 30 IEL/100 enterocytes: Pathological "lymphocytosis"

Alternative proposed methods is the presence of over 6-12 IELs per 20 enterocytes at the tips of duodenal villi. In the jejunum, the cutoff is at over 40 IELs per 100 enterocytes.

Suggestive but not specific findings for enterocytes are: decreased height, intracytoplasmic vacuolation and reduction or absence of the brush border.

Differential diagnoses

If findings are suggestive of celiac disease, look for at least the following differential diagnoses:

• 

  Whipple's disease: The lamina propria contains swollen histiocytes and lipid vacuoles.

• 

  Giardia lamblia: Organisms shaped like teardropd or pears, with paired nuclei, seen in the lumen between villi.

Microscopy report

Example in an unremarkable specimen:

Small intestine, biopsy: Duodenal mucosa, negative for significant histopathologic changes. Negative for celiac disease.

Example in suspected celiac disease:

Small intestine, biopsy: Marked villous atrophy with increased intraepithelial lymphocytes, consistent with celiac sprue. Correlation with serologic testing is recommended.

Colorectal polyp

Gross examination

Further information: Colon

Tissue selection and trimming

There is a separate article for the Grossing of minimally invasive colorectal surgery.

Depending on sample format:

• Biopsies and polyps of <4 mm are embedded in their entirety. Samples less than 0.3 mm should be stained with eosin to avoid getting lost processing.
• Polyps 4-8 mm with short stem or without stem: Identify the excision surface and divide the polyp longitudinally through the excision surface.
• Polyps > 8 mm with a stem long enough to make it possible to take a transverse, whole slice from the stem closest to the excision surface: First, take a transverse slice through the peripheral portion of the stem, encompassing the entire circumference. Then take a 3-4 mm thick slice longitudinally through the polyp and the middle of the stem, after which the two remaining parts on either side are cut into equally thick slices, parallel to the previous slice.
• Polyps >8 mm with short stem or without stem: Identify the excision surface and cut out a 3-4 mm thick disk that extends longitudinally through the center of the excision surface. Then divide the two remaining portions into equally thick slices, parallel to the previous slice.
• Polyps that come in parts: Pick out the largest pieces, which are cut as similar as possible to above. Small fragments are sieved and embedded in a separate box.

Gross reporting

• Polyp and/or fragment sizes
• Presence or absence of stem of polyps

Example, for a gastrointestinal biopsy:

Labeled: "Sigmoid colon biopsy". The specimen is received in formalin and consists of 4 fragments of pink-tan tissue with a vaguely recognizable mucosal surface, mixed with food-like material. The fragments measure 0.2-0.3 cm in greatest dimension. The entire specimen is submitted for microscopic examination in one cassette.

Microscopic evaluation

Major signs

Look particularly for these, to help sorting into proper diagnosis in next section:

• 

  Proliferation (as compared to normal crypt at left in image): When superficial or otherwise excessive it indicates at least an adenoma.

• 

  Serrations, a feature of both traditional and serrated adenomas.

Main types

Consider at least the following conditions:

Incidences and malignancy risks of various types of colorectal polyps.

Colorectal polyps

Type	Risk of containing malignant cells	Histopathology		Image
Hyperplastic polyp	0%	No dysplasia. Mucin-rich type: Serrated (“saw tooth”, pictured) appearance, containing glands with star-shaped lumina. Crypts that are elongated but straight, narrow and hyperchromatic at the base. All crypts reach to the muscularis mucosae. Goblet cell-rich type: Elongated, fat crypts and little to no serration. Filled with goblet cells, extending to surface, which commonly has a tufted appearance.
Tubular adenoma	2% at 1.5cm	Low to high grade dysplasia	Over 75% of volume has tubular appearance.
Tubulovillous adenoma	20% to 25%		25%-75% villous
Villous adenoma	15% to 40%		Over 75% villous
Sessile serrated adenoma (SSA)		Basal dilation of the crypts Basal crypt serration Crypts that run horizontal to the basement membrane (horizontal crypts) Crypt branching.
Traditional serrated adenoma		Protuberant villi with slit-like serrations. Pseudostratified epithelial columnar cells shapes. Eosinophilic cytoplasm and dark, pencil-like nuclei. Golblet cells are present.
Colorectal adenocarcinoma	100%	In carcinoma in situ (Tis): cancer cells invading into the lamina propria, and may involve but not penetrate the muscularis mucosae. Can be classified as "high-grade dysplasia", because prognosis and management are essentially the same. Invasive adenocarcinoma: Extending through the muscularis mucosae into the submucosa and beyond.

If you only see normal mucosa but the order/endoscopy says polyp, take additional levels from the paraffin block.

Other benign

Colonic lipoma, a benign polyp, here being submucosal and pedunculated.

If a more specific diagnosis cannot readily be made, clearly non-malignant colorectal polyps may simply be reported as such.

Further information: Evaluation of tumors

Microscopy report

It should include:

• Size of polyp (from gross examination)
• Histopathologic type
• Depth of growth and/or infiltration

• Whether the resection is radical

Optionally, it can include degree of differentiation and/or dysplasia.

Example:

50 mm large tubulovillous adenoma with up to high grade columnar epithelial dysplasia. No infiltration. Radical excision.

If multiple polyps are submitted in one container, you may count the amount of each polyp type if you can, but if the amount of fragments in microscopy exceeds the amount of fragments purportedly submitted, then you can simply write "fragments of", like the following example:

Fragments of tubular adenoma and hyperplastic polyp.

More details are given in main articles of histopathologic types.

  See also: General notes on reporting

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Hyperplastic polyp

Commonly presents as a colorectal polyp.

Gross evaluation

Further information: Colon

Tissue selection and trimming

There is a separate article for the Grossing of minimally invasive colorectal surgery.

Depending on sample format:

• Biopsies and polyps of <4 mm are embedded in their entirety. Samples less than 0.3 mm should be stained with eosin to avoid getting lost processing.
• Polyps 4-8 mm with short stem or without stem: Identify the excision surface and divide the polyp longitudinally through the excision surface.
• Polyps > 8 mm with a stem long enough to make it possible to take a transverse, whole slice from the stem closest to the excision surface: First, take a transverse slice through the peripheral portion of the stem, encompassing the entire circumference. Then take a 3-4 mm thick slice longitudinally through the polyp and the middle of the stem, after which the two remaining parts on either side are cut into equally thick slices, parallel to the previous slice.
• Polyps >8 mm with short stem or without stem: Identify the excision surface and cut out a 3-4 mm thick disk that extends longitudinally through the center of the excision surface. Then divide the two remaining portions into equally thick slices, parallel to the previous slice.
• Polyps that come in parts: Pick out the largest pieces, which are cut as similar as possible to above. Small fragments are sieved and embedded in a separate box.

Gross reporting

• Polyp and/or fragment sizes
• Presence or absence of stem of polyps

Example, for a gastrointestinal biopsy:

Labeled: "Sigmoid colon biopsy". The specimen is received in formalin and consists of 4 fragments of pink-tan tissue with a vaguely recognizable mucosal surface, mixed with food-like material. The fragments measure 0.2-0.3 cm in greatest dimension. The entire specimen is submitted for microscopic examination in one cassette.

Microscopic evaluation

There are two main types of hyperplastic polyps, which have genetic differences, as well as different histologic structure, but no significant differences clinically:

• A microvesicular mucin-rich type
• A goblet cell-rich type

Mucin-rich type

(Mucin-rich) hyperplastic polyp.

(Mucin-rich) hyperplastic polyp, with a tangential section, showing serrations peripherally (superficially) and narrow lumina centrally (crypts).

Characteristics:

• Serrations (“saw tooth appearance”) of the luminal portion.
• Star-shaped lumina.
• Crypt elongation but they are straight, narrow and hyperchromatic at the base. All crypts reach to the muscularis mucosae.

The basement membrane is frequently thickened. This is the usual form of hyperplastic polyps, and they do not need to be reported as "mucin-rich".

Histologic structure in goblet cell-rich type

Elongated, fat crypts and little to no serration. Therefore, they may not be obvious without comparing to adjacent normal intestinal wall.

They are filled with goblet cells, extending to surface, which commonly has a tufted appearance.

Epithelial misplacement

Infrequently, the epithelium is misplacement into the submucosa. Such polyps have been termed "inverted hyperplastic polyps". They appear to be restricted to the sigmoid colon and rectum. The misplaced epithelium is mucin-depleted , similar to the basal 1/3 of the polyp. The misplacement is accompanied by the lamina propria, and is continuous with overlying polyp through a gap in the muscularis mucosae. It may require slices at multiple levels to demonstrate microscopically.

In such cases adjacent hemorrhage and hemosiderin deposition is common. Collagen type IV stain will have a strong continuous staining around nests.

Cellular structure

Nuclei are small, regular, round and basal in the luminal half of the crypts, most reliably evaluated near the luminal surface.

There are proliferative changes at the base of crypts, where nuclei are enlarged, the nucleus/cytoplasm ratio is elevated.

Differential diagnoses

The main differential diagnosis for a hyperplastic polyp is adenoma, which generally display:

• Nuclear stratification
• Loss of polarity
• Dysplasia

However, the deep proliferative zones and reactive processes closely mimic changes seen in colorectal adenomas.

Sessile serrated adenoma with minimal deviation dysplasia, wherein architectural changes are subtle, with mild crowding of crypts separated by less lamina propria and showing some degree of disorganization.

Sessile serrated adenoma

• A sessile serrated adenoma is suspected in case of any of the following:

• Size ≥0.5 cm
• Location in right colon

If both latter findings are present, it is almost always a SSA. Other features causing a suspicion for sessile serrated adenoma are:

• Dilation of crypts
• Branching of crypts
• Horizontal glands at the base
• Mature mucinous cells at the base of crypts
• Location in the proximal colon (cecum, ascending, and transverse colon), whereas hyperplastic polyps are most common in the sigmoid colon and rectum. However, both may occur throughout the colon.

Tubular colorectal adenoma

Hyperplastic polyp	Tubular adenoma
Nu dysplasia	Dysplasia
Proliferative epithelium restricted to base	Proliferative epithelium present at the surface
Gland lining cells mature at the surface	No surface maturation

• 

  Non-proliferative crypt (left) versus proliferative dysplastic crypt (large at right, with crowded hyperchromatic nuclei).

• 

  In nuclear crowding, also look for inflammation: Here a hyperplastic polyp with inflammatory reactive changes, reminiscent of adenoma.

Further information: Evaluation of tumors and Tubular colorectal adenoma

Microscopic report

Usually as follows:

(<Sigmoid / Ascending / etc.> colon polyp, polypectomy:) Hyperplastic polyp.

Generally don't report hyperplastic polyp elements of polyps with potential malignant progression (such as tubular and ⁄or villous adenomas), because the patient's clinical management will be based on the more concerning elements.

Tubular and ⁄or villous adenoma

Microscopic evaluation

Criteria

Tubular adenoma with low-grade dysplasia.

Dysplastic changes should involve at least the upper half of the crypts and the luminal surface.

• Nuclear dysplasia is mandatory to diagnose adenoma. It involves:

• Nuclear atypia: Enlarged hyperchromatic nuclei (that is, dark purple) that are oval or frequently elongated, and with high nucleus to cytoplasm ratio.
• Other cellular atypia: Often nuclear stratification, nuclear crowding (that is, nuclei are bunched-up) and loss of polarity

• Always changes in gland architecture, such as:

• Enlarged crypts
• Gland budding, or otherwise irregular glands

• Mucin depletion is often seen, but is not required
• Goblet cell reduction.

Differential diagnoses

Hyperplastic polyp

Hyperplastic polyp	Tubular adenoma
Nu dysplasia	Dysplasia
Proliferative epithelium restricted to base	Proliferative epithelium present at the surface
Gland lining cells mature at the surface	No surface maturation

• 

  Non-proliferative crypt (left) versus proliferative dysplastic crypt (large at right, with crowded hyperchromatic nuclei).

• 

  In nuclear crowding, also look for inflammation: Here a hyperplastic polyp with inflammatory reactive changes, reminiscent of adenoma.

Colorectal carcinoma

Colorectal adenocarcinoma (in this case, not otherwise specified).

Colorectal carcinoma (mainly adenocarcinoma) is distinguished from an adenoma (mainly tubular and ⁄or villous adenomas) mainly by invasion through the muscularis mucosae.

Also, carcinoma also commonly displays:

• Varying degrees of gland formation with tall columnar cells
• Frequenty desmoplasia
• Dirty necrosis, consisting of extensive central necrosis with granular eosinophilic karyorrhectic debris. Garland of cribriform glands are frequently found in their vicinity.

Low or high grade

In low-grade lesions, the crypts should maintain a resemblance to normal colon.

High-grade dysplasia, in this case seen mainly as loss of cell polarity, as cells become more plump and haphazard than the elongated and parallel nuclei of surrounding low-grade dysplasia.

Typical findings in low-grade versus high-grade tubular and ⁄or villous adenoma

	Low-grade	High grade
Crowding	Pseudo-stratification to early stratification	More substantial stratification
Nuclear pleomorphism and atypical mitoses	Absent or minimally present	Present
Loss of cell polarity	Minimal	More significant
Crowding, cribriform, or complex architecture	No significant	Present

High grade lesions also typically have:

• Cribriform architecture, consisting of juxtaposed gland lumens without stroma in between, with loss of cell polarity. Rarely, they have foci of squamous differentiation (morules). This should be distinguished from cases where piles of well-differentiated mucin-producing cells appear cribriform. In such piles, nuclei show regular polarity with apical mucin, and their nuclei are not markedly enlarged.
• Increased nucleus to cytoplasm ratio.
• More "open" appearing nuclei with increasingly prominent nucleoli
• Back-to-back glands

• 

  Tubular adenoma with high-grade dysplasia.

Tubular or villous

Colorectal adenoma

Type	Histopathology	Image
Tubular adenoma	Over 75% of volume has tubular appearance.
Tubulovillous adenoma	25%-75% villous
Villous adenoma	Over 75% villous

Length of villi must be at least twice the depth of the normal mucosal thickness.

Further information: Evaluation of tumors

Further workup

Look for and evaluate any lymph nodes in the tissue specimen, for possible malignancy.

Dissecting pools of mucin at the base of any adenoma should be evaluated for the possibility of mucinous carcinoma.

Report

• Tubular, tubulovillous or villous adenoma.
• Any high-grade component (whereas low-grade does not need to be stated in the report as it is presumed otherwise).
• ((Adenoma size))
• ((Whether it is radically resected.))

If any lymph nodes are found in the tissue sample, report the presence or absence of malignancy in any of them.

Example:

Sigmoid colon polyp x2, polypectomies: One tubular adenoma and one tubulovillous adenoma.

Sessile serrated adenoma

Microscopic examination

The characteristics of sessile serrated adenoma are:

• Sawtooth serrations of the epithelium
• Abundant mucin, similar to hyperplastic polyps
• Basal crypt dilation, with mucous retention, and lateral spread of the crypt bases, commonly described as boot shaped or anchor shaped crypts.

Variations

On low magnification, a sessile serrated adenoma may be flat (left) or protuberant (right):

• 
• 

Microscopic report

A brief report is sufficient:

Cecum polyp, polypectomy: Sessile serrated adenoma.

Differential diagnoses

• 

  Traditional serrated adenoma, having protuberant exophytic configuration, complex villous growth pattern, and cells with abundant eosinophilic cytoplasm and elongated penicillate nuclei with dispersed chromatin.

• 

  Hyperplastic polyp, should not have dilation of crypts, branching of crypts or horizontal glands at the base. Size larger than 0.5 cm slightly indicates a sessile serrated adenoma.

Regarding location, the diagnosis of a sessile serrated adenoma is supported by a location within the proximal colon (cecum, ascending, and transverse colon), while hyperplastic polyps are most common in the sigmoid colon and rectum. However, both may occur throughout the colon.

Traditional serrated adenoma

Microscopic evaluation

This case lacks the typical eosinophilic cytoplasm, but otherwise typical with protuberant villiform growth pattern with slit-like serrations and presence of goblet cells.

• Protuberant villi with slit-like serrations.
• Pseudostratified epithelial columnar cells shapes.
• Eosinophilic cytoplasm and dark, pencil-like nuclei.
• Golblet cells are present.

Differential diagnosis

• 

  Sessile serrated adenoma: sessile rather than protuberant exophytic configuration, and cells generally have smaller and less eosinophilic cytoplasm.

Colitis

Microscopic evaluation

• Look for signs of active (or acute) and/or chronic colitis:

Signs of active (or acute) colitis:

• 

  Neutrophilic cryptitis (neutrophils within crypt epithelium)

• 

  Crypt abscesses (luminal neutrophilic aggregates)

• 

  In fact, one neutrophil is enough for the feature

• 

  Normal mucosal fold for comparison

• 

  Gland destruction

• 

  Ulceration (seen here as absence of epithelium, and granulation tissue with many fibroblasts)

Active colitis may also cause ischemic changes (including superficial necrosis, hemorrhage, crypt shrinkage/dropout, fibrin thrombi)

Signs of chronic colitis:

• 

  Crypt degeneration

• 

  Crypt branching and other architectural distortions

• 

  Paneth cell (pictured) or gastric metaplasia (only applies in the left colon and rectum)

Chronic colitis may also cause elevation of crypts relative to the muscularis mucosa. Other findings include basal plasmacytosis and mucin depletion.

Have a high threshold for chronic colitis in the rectum, as it often shows chronic changes even without any disease.

Special types

In addition, look for the following types of colitis:

• 

  Lymphocytic colitis, characterized by > 20 intraepithelial lymphocytes per 100 epithelial cells, away from lymphoid aggregates.

• 

  Lymphocytic colitis generally also shows increased lymphocytes, plasma cells, eosinophils, and occasional neutrophils in lamina propria, but with preserved architecture

• 

  Collagenous colitis, with a thickened subepithelial collagen band that is typically more than 10 μm in thickness.

• 

  Compare to normal colonic mucosa, which can have a band of basal epithelial cytoplasm.

(Consider the clinical and/or endoscopic findings in the evaluation.)

Further workup of colitis

Distinguish:

• (Severity: Mild, moderate or severe.)
• Presence of crypt regeneration, granuloma, inflammatory pseudomembranes, parasites or viral inclusions.
• Presence of epithelial dysplasia or even cancer. If unsure of the latter, consider immunohistochemistry for cytokeratins such as CK AE1/AE3. Further information: Evaluation of suspected malignancies
• ((Distribution: Patchy versus diffuse))

• 

  A non-necrotizing granuloma. It is seen as an aggregate of histiocytes in the center of the image, having ample eosinophilic cytoplasm.

• 

  Dysplastic crypt at right. In such case, consider tubular and ⁄or villous adenoma.

• 

  Look particularly in ulcers for signet ring cells.

Apart from histologically defined diagnoses (collagenous colitis, lymphocytic colitis), there is no need to speculate about the exact underlying diagnosis (such as Crohn's disease, ulcerative colitis etc.).

Microscopy report

A biopsy report generally does not state the diagnosis, but should state any presence of chronic colitis, give an indication of disease activity, as well as state the presence of any epithelial damage (erosions and ulcerations).

Example of a normal sample, when colitis was suspected in the referral:

(Colonic/Rectal mucosa without significant histopathologic changes.) Negative for (acute and chronic) colitis.

Example of findings of both active and chronic colitis:

(Ascending, transverse, descending, and sigmoid colon, biopsies:) ((Patchy)) (mild) chronic active colitis((, with associated cryptitis and crypt abscesses.)) (Negative for ulceration, granulomata and dysplasia.)

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