Tubular and ⁄or villous adenoma
Further information: Colon
Tissue selection and trimming
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.
- 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.|
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:
- 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.
|Hyperplastic polyp||Tubular adenoma|
|Proliferative epithelium restricted to base||Proliferative epithelium present at the surface|
|Gland lining cells mature at the surface||No surface maturation|
In carcinoma in situ (Tis), cancer cells invade into the lamina propria, and may involve but not penetrating the muscularis mucosae. This can be classified as an adenoma with "high-grade dysplasia", because prognosis and management are essentially the same.
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.
|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 or villous
|Type||Risk of containing malignant cells||Histopathology||Image|
|Tubular adenoma||2% at 1.5cm||Over 75% of volume has tubular appearance.|
|Tubulovillous adenoma||20% to 25%||25%-75% villous|
|Villous adenoma||15% to 40%||Over 75% villous|
Length of villi must be at least twice the depth of the normal mucosal thickness.
- Further information: Evaluation of tumors
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.
- Adenoma size
- Tubular, tubulovillous or villous adenoma.
- Whether it is radically resected.
If any lymph nodes are found in tissue sample, report the presence or absence of malignancy in any of them.
- See also: General notes on reporting
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-"This book is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/)"
- Minhhuyen Nguyen. Polyps of the Colon and Rectum. MSD Manual. Last full review/revision June 2019
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