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Author: Mikael Häggström [note 1]


Generally 10% neutral buffered formalin.

  See also: General notes on fixation

Main requests


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

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

Gross processing

  • Measure the length of the appendix.[1]
  • ((Note its shape.[1] ))
  • 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.[1]
  • ((Note the wall thickness[1]))
  • Look mainly for:[1]
  • 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[note 2]
  • 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

  • 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:[1]

  • 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


((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.


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.


  • 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.


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

Example, using image at right:

Histopathology of appendicitis.jpg

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

  See also: General notes on reporting


  1. For a full list of contributors, see article history. Creators of images are attributed at the image description pages, seen by clicking on the images. See Patholines:Authorship for details.
  2. En face means that the section is tangential to the region of interest (such as a lesion) of a specimen. Further information: Gross_processing#Cutting

Main page


  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Monica Dahlgren, Janne Malina, Anna Måsbäck, Otto Ljungberg (1997-02-13). Lilla utskärningen.
  2. Elkbuli, Adel; Sanchez, Carol; McKenney, Mark; Boneva, Dessy (2019). "Incidental neuro-endocrine tumor of the appendix: Case report and literature review ". Annals of Medicine and Surgery 43: 44–47. doi:10.1016/j.amsu.2019.05.015. ISSN 20490801. 
  3. Hajjar, Roy; Dubé, Pierre; Mitchell, Andrew; Sidéris, Lucas (2019). "Combined Mucinous and Neuroendocrine Tumours of the Appendix Managed with Surgical Cytoreduction and Oxaliplatin-based Hyperthermic Intraperitoneal Chemotherapy ". Cureus. doi:10.7759/cureus.3894. ISSN 2168-8184. 

Image sources