Adenosquamous carcinoma: a report of nine cases with p63 and cytokeratin 5/6 staining.

Adenosquamous carcinoma, a rare tumor of the skin with few reported cases in the literature, has not been studied with p63, cytokeratin 5/6 and cytokeratin 7. We stained nine such tumors with these markers. Histologically, the tumors showed superficial, atypical islands of keratinocytes in close association with islands displaying glandular differentiation. Clinically, lesions favored the head and trunk, and a subset of cases showed aggressive behavior. All tumors marked with p63 and cytokeratin 5/6, substantiating that diffuse positivity with these stains is supportive of a primary cutaneous origin. Six tumors stained focally in luminal areas with cytokeratin 7. Recognition of adenosquamous carcinoma is important for appropriate therapy, and stains for p63 and cytokeratin 5/6 may be helpful in ruling out metastatic adenocarcinoma.