Non-neoplastic
– Compatible with hemorrhoid
– Inflammatory cloacogenic polyp (mucosal prolapse polyp)
Tumors/polyps
– Fibroepithelial polyp
– Low-grade squamous intraepithelial lesion (AIN 1, Condyloma)
– High-grade squamous intraepithelial lesion (AIN 2)
– High-grade squamous intraepithelial lesion (AIN 3)
– Invasive squamous cell carcinoma
Anal adenocarcinoma arises from the glandular epithelium of the anal canal (either mucosal or extramucosal)
If mucosal, then it stains like a colon adenocarcinoma (CK7+/-, CK20+, CDX2+)
If it is extramucosal, from the anal glands, it stains CK7+, CK20-, CDX2-)
– Anal adenocarcinoma
– Extramammary Paget’s disease (see comment)
If the stains favor a cutaneous/apocrine primary (CK7+, CK20-, CDX2-, GCDFP+)
COMMENT: Histologic sections of the anal biopsy show an intraepidermal proliferation of malignant cells with pale cytoplasm, prominent nucleoli, and Pagetoid spread. A panel of immunohistochemical stains (outlined below) demonstrate an profile most suggestive of cutaneous/apocrine origin. No invasive carcinoma is identified. Clinical correlation is recommended.
If the stains favor an occult colorectal primary (CK7-, CK20+, CDX2+, GCDFP-)
COMMENT: Histologic sections of the anal biopsy show an intraepidermal proliferation of malignant cells with pale cytoplasm, prominent nucleoli, and Pagetoid spread. A panel of immunohistochemical stains (outlined below) demonstrate an profile most suggestive of an underlying synchronous or metachronous colorectal primary. No invasive carcinoma is identified in the submitted tissue. Careful clinical and endoscopic correlation is recommended.
Last updated: September 10, 2019