Difference between revisions of "Squamous metaplasia of the rectum/anus"
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'''Squamous metaplasia of the anus''' is a metaplastic change of the columnar epithelium. It can histologically mimic [[anal intraepithelial neoplasia]] (AIN), especially. [[high-grade squamous intraepithelial lesion]] (HSIL). | '''Squamous metaplasia of the anus''' is a metaplastic change of the columnar epithelium. It can histologically mimic [[anal intraepithelial neoplasia]] (AIN), especially. [[high-grade squamous intraepithelial lesion]] (HSIL). | ||
==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: | |||
*[[Anal intraepithelial lesion]]. | |||
===Images=== | ===Images=== | ||
Revision as of 02:09, 16 June 2016
Squamous metaplasia of the anus is a metaplastic change of the columnar epithelium. It can histologically mimic anal intraepithelial neoplasia (AIN), especially. high-grade squamous intraepithelial lesion (HSIL).
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.