Aggressive digital papillary adenocarcinoma: a silent malignancy masquerading as acquired digital fibrokeratoma.

Aggressive digital papillary adenocarcinoma (ADPAC) is a rare cutaneous malignant tumor. We report on a 42-year-old man presenting with a nontender firm nodule on his right thumb that had been present for 3 years. The lesion clinically resembled an acquired digital fibrokeratoma, but was found to be an ADPAC after pathologic study of the excised specimens. Consequently, re-excision with a full-thickness skin graft was performed. No signs of local recurrence or metastasis were noted 2.5 years postoperatively. ADPAC should be suspected with an indolent digital tumor even without any clinical change or symptom for years. An excisional biopsy is warranted for correct diagnosis. Appropriate treatment with re-excision or amputation can greatly reduce the recurrence rate to 5%, compared with 50% after simple excision alone.