Difference between revisions of "Squamous metaplasia of the rectum/anus"
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'''Squamous metaplasia of the rectum''' is a metaplastic change of the columnar epithelium of the rectum. | '''Squamous metaplasia of the rectum/anus''' is a metaplastic change of the columnar epithelium of the rectum. | ||
It can histologically mimic [[anal intraepithelial neoplasia]] (AIN), especially. [[high-grade squamous intraepithelial lesion]] (HSIL). | It can histologically mimic [[anal intraepithelial neoplasia]] (AIN), especially. [[high-grade squamous intraepithelial lesion]] (HSIL). | ||
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==General== | ==General== | ||
*Present in the transformation zone between the columnar epithelium of the [[rectum]] and squamous epithelium of the [[anus]] - similar to the transformation zone of the [[uterine cervix]].<ref name=pmid20436833>{{Cite journal | last1 = Pineda | first1 = CE. | last2 = Welton | first2 = ML. | title = Management of anal squamous intraepithelial lesions. | journal = Clin Colon Rectal Surg | volume = 22 | issue = 2 | pages = 94-101 | month = May | year = 2009 | doi = 10.1055/s-0029-1223840 | PMID = 20436833 }}</ref> | *Present in the transformation zone between the columnar epithelium of the [[rectum]] and squamous epithelium of the [[anus]] - similar to the transformation zone of the [[uterine cervix]].<ref name=pmid20436833>{{Cite journal | last1 = Pineda | first1 = CE. | last2 = Welton | first2 = ML. | title = Management of anal squamous intraepithelial lesions. | journal = Clin Colon Rectal Surg | volume = 22 | issue = 2 | pages = 94-101 | month = May | year = 2009 | doi = 10.1055/s-0029-1223840 | PMID = 20436833 }}</ref> | ||
Note: | |||
*The anatomy & histology of the anus covered in the ''[[anus]]'' article. | |||
==Microscopic== | ==Microscopic== | ||
Latest revision as of 02:42, 16 June 2016
Squamous metaplasia of the rectum/anus is a metaplastic change of the columnar epithelium of the rectum.
It can histologically mimic anal intraepithelial neoplasia (AIN), especially. high-grade squamous intraepithelial lesion (HSIL).
General
- Present in the transformation zone between the columnar epithelium of the rectum and squamous epithelium of the anus - similar to the transformation zone of the uterine cervix.[1]
Note:
- The anatomy & histology of the anus covered in the anus article.
Microscopic
Features:
- Uniform cell spacing - no crowding - key feature.
- Nuclei are uniform size and round.
- +/-Nucleoli present.
- Distinct cell borders
- +/-Intercellular bridges (due to edema) - common.
Negatives:
- No mitoses/rare basal mitoses - think cancer/AIN if you see 'em.
- Usually no hyperchromatism (think cancer/CIN if you see it).
DDx:
Images
ISM - very low mag.
ISM - low mag.
ISM - intermed. mag.
ISM - high mag.
IHC
- p16 -ve
- Usually weak-to-moderate patchy, not full thickness.
- Ki-67 - scattered cells positive.
See also
References
- ↑ Pineda, CE.; Welton, ML. (May 2009). "Management of anal squamous intraepithelial lesions.". Clin Colon Rectal Surg 22 (2): 94-101. doi:10.1055/s-0029-1223840. PMID 20436833.