Cutaneous digital papillary adenocarcinoma: a clinicopathologic study of 31 cases of a rare neoplasm with new observations

Aggressive digital papillary adenocarcinoma is a rare tumor predominantly involving the distal end of digits. We examined 31 cases of this distinctive tumor for clinicopathologic, immunohistochemical, and follow-up data where available. Males were predominantly affected (n=29), with a mean age of 43 years (range, 14 to 67 y). Three lesions were reported in patients below the age of 20 years. All cases involved a finger (n=26) or a toe (n=5), with most involving the distal portion of the digit (n=29). Two lesions involved the base of the digit/webspace. Histopathologically, all tumors involved the dermis with subcutaneous extension in 14 cases. The lesions demonstrated a multinodular solid and/or cystic pattern, with focally infiltrative architecture in 21 cases. Papillary projections were: prominent (n=10), focal (n=15), or not identified (n=6). Within the solid component, tubular structures were present at least focally in all cases. Cytologic atypia ranged from mild (n=8) to moderate (n=20), but was focally severe in 3 cases. Mitotic count ranged from