Aggressive digital papillary adenocarcinoma arising on the right great toe.

A 20-year-old Japanese man with aggressive digital papillary adenocarcinoma on the right great toe was presented. The tumor was comprised of multiple lobules of epithelial cells exhibiting solid areas, lacking cystic spaces. A pattern of fused back-to-back glands lined by cuboidal to low columnar epithelial cells with little evidence of papillary formations was observed. Apocrine-like decapitation secretion was not observed, and continuity of the tumor to the epidermis was evident. The neoplastic cells were immunohistochemically positive for S-100 protein, but negative for epithelial membrane antigen (EMA), carcinoembryonic antigen (CEA) and gross cystic disease fluid protein (GCDFP). Intraluminal contents, however, showed positive reactivity with CEA and EMA. On the basis of their histologic and immunohistochemical features, the tumor was diagnosed as aggressive digital papillary adenocarcinoma.