A slowly enlarging mass on the finger.

An otherwise healthy 71-year-old woman presented with an asymptomatic mass on her right 4th finger that had been slowly enlarging over the past 2 years. On physical examination, there was a tan-pink, freely mobile, rubbery 9-mm papule with a central keratotic plug located over the extensor aspect of the proximal interphalangeal joint of the right 4th finger. A 3-mm punch biopsy of the lesion was performed. Histopathologic findings were consistent with a diagnosis of aggressive digital papillary adenocarcinoma (ADPAca), an adnexal tumor with high metastatic potential that is unfortunately commonly misdiagnosed owing to its rarity and nondescript appearance. Aggressive surgical treatment including radical excision or digital amputation with or without sentinel lymph node biopsy is advocated in the treatment of ADPAca.