Anus

• anal plasmacytic infiltration
  16 September 2016

  Examples
  anal syphilis: plasma cells, perivascular inflammation, sometimes granulomas - Treponema pallidum IHC https://twitter.com/saraehiggins1/status/776538729829859329
  See also
  cellular infiltration inflammatory infiltration
  other localizations nodal plasmacytic infiltration digestive plasmacytic infiltration bronchial plasmacytic infiltration pulmonary plasmacytic infiltration renal plasmacytic infiltration anal plasmacytic (...)

• anal epithelial dysplasia
  22 August 2016

  Anal squamous intraepithelial lesions
  See : anal intraepithelial neoplasia (AIN )
  Stage 0 – anal intraepithelial neoplasia / anal carcinoma in situ (AIN )
  There are different grades of AIN :
  AIN1 means the abnormal cells are in the lower one third of the skin covering the anus
  AIN2 means the abnormal cells are in the lower two thirds of the skin
  AIN3 means the abnormal cells are in the full thickness of the skin of the (...)

• anal squamous metaplasia
  29 June 2016

  immature squamous metaplasia of the anus
  Images
  Wikimedia: immature squamous metaplasia of the anus
  Variants
  immature squamous metaplasia of the anus Immature squamous metaplasia can closely mimic severe squamous dysplasia/high grade squamous intraepithelial lesion (HSIL). p16 is negative (p16- ) and Ki-67 shows minimal basal staining.
  See also
  anal anomalies

• anal mucosal anomalies
  29 June 2016

  Examples
  anal epithelial metaplasia squamous metaplasia of the anus immature squamous metaplasia of the anus
  anal epithelial dysplasia
  See also
  anal anomalies

• anal mucosa
  29 June 2016

  Components
  anal epithelium
  anal lamina propria
  Pathology
  anal mucosal anomalies

• HPV-associated anal neuroendocrine carcinoma
  8 April 2016

  Neuroendocrine carcinoma (NEC) of the anal canal is exceedingly rare and its histogenesis is poorly understood.
  SIN may be a precursor of anal canal NEC and that HPV18 may play an important role in the histogenesis of anal canal NEC, similar to its role in cervical NEC.
  References
  Anal canal neuroendocrine carcinoma associated with squamous intraepithelial neoplasia: a human papillomavirus 18-related lesion. Ohtomo R, Sekine S, Taniguchi H, Tsuda H, Moriya Y, Kushima R. Pathol Int. 2012 (...)

• anal neuroendocrine carcinoma
  8 April 2016

  Anal canal neuroendocrine carcinoma
  Neuroendocrine carcinoma (NEC) of the anal canal is exceedingly rare and its histogenesis is poorly understood.
  SIN may be a precursor of anal canal NEC and that HPV18 may play an important role in the histogenesis of anal canal NEC, similar to its role in cervical NEC.
  References
  Anal canal neuroendocrine carcinoma associated with squamous intraepithelial neoplasia: a human papillomavirus 18-related lesion. Ohtomo R, Sekine S, Taniguchi H, Tsuda H, (...)

• anal Paget disease
  21 March 2016

  perianal Paget disease
  Images
  anal or perianal Paget disease https://twitter.com/GIPathologyURMC/status/692393378072432640 https://twitter.com/BeynonMD/status/711624198733434880 https://twitter.com/WMKleinMD/status/662264201231138816
  Immunochemistry
  Perianal Paget disease can express CK20 & CDX2 even when skin primary (no association with rectal adenocarcinoma).
  See also
  extramammary Paget’s disease
  perianal (...)

• adenoma of the anal canal
  14 September 2015

  Anal canal adenoma is an extremely rare disease that has the potential to transform into a malignant tumor. Reports underscore the importance of careful observations throughout colonoscopy to detect precancerous lesions, particularly in anatomically narrow segments.
  Open references
  Metachronous tubulovillous and tubular adenomas of the anal canal. Nozawa H, Ishihara S, Morikawa T, Tanaka J, Yasuda K, Ohtani K, Nishikawa T, Tanaka T, Kiyomatsu T, Kawai K, Hata K, Kazama S, Yamaguchi H, (...)

• basal cell carcinoma of the anal region
  10 May 2013

  basal cell carcinoma of the anal region
  Basal cell carcinoma of the anal region is rare and morphologically difficult to distinguish from basaloid squamous cell carcinoma, particularly on biopsies. This distinction has therapeutic and prognostic implications.
  Perianal location, retraction artifact, and lack of atypical mitoses are histological features that help distinguish basal cell carcinoma from basaloid squamous cell carcinoma.
  An in situ component, when present, supports the (...)

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