Surgical Pathology Criteria

Adenocarcinoma of the Anus

Differential Diagnosis

Colorectal Type Adenocarcinoma of the Anus Extra-mucosal (Fistula/Anal Gland) Type Adenocarcinoma of the Anus
Usually has identifiable surface component No surface mucosal component
No association with chronic fistula Most case associated with chronic fistula
CK7 variably positive CK7 positive
CK20 positive CK20 negative
CDX2 positive CDX2 negative
Small numbers of cases have been tested


Squamous Carcinoma of the Anus Poorly Differentiated Adenocarcinoma of the Anus
CK5/6 and p63 virtually always positive CK5/6 and p63 negative
CK20 negative CK20 positive if rectal type; negative if perianal gland type
High risk HPV may be seen in both


  • Melanoma should be ruled out before the diagnosis of poorly differentiated adenocarcinoma is made
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