Anal duct carcinoma: a report of 5 cases.

Anal duct carcinoma (ADC) is a rare lesion composed of glands undermining non-neoplastic squamous epithelium. We describe the clinicopathologic characteristics and follow-up of 5 cases of ADC. Four definitive cases had tissue available for immunohistochemistry (IHC; CK7, CK20, prostate-specific antigen [PSA], estrogen/progesterone receptors [ER/PR], and p16) and in situ hybridization (ISH) for high-risk human papillomavirus (HR-HPV); a fifth case, with a history of ADC, had limited tissue for immunolabeling with only CK7, CK20, and p16. The mean patient age was 69.8 years. All 5 cases were CK7-positive and p16-negative. Four of 5 cases were CK20-negative. All cases with sufficient tissue (4/4) were negative for HR-HPV by ISH, PSA-negative (men), and ER/PR-negative (women). Four of 5 patients had previous malignancies, and in all 4 cases with sufficient tissue, metastasis was excluded with IHC. Of 5 patients, 3 developed metastases, whereas 2 had isolated local recurrences. ADCs are neoplasms with metastatic potential and can result in poor outcomes.