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 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==
==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==
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==See also==
==See also==
*[[Squamous metaplasia]].
*[[Squamous metaplasia]].
==References==
{{Reflist|1}}


[[Category:Gastrointestinal pathology]]
[[Category:Gastrointestinal pathology]]
[[Category:Dermatopathology]]
[[Category:Dermatopathology]]

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.
  • 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

IHC

  • p16 -ve
    • Usually weak-to-moderate patchy, not full thickness.
  • Ki-67 - scattered cells positive.

See also

References

  1. 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.