Metastatic aggressive digital papillary adenocarcinoma.

A 52-year-old white man presented with 2 complex cystic masses in his left inguinal region. On histopathologic examination, an asymptomatic nodule between the third and fourth metatarsal heads was diagnosed as an aggressive digital papillary adenocarcinoma (ADPAca), and the complex cysts from the groin represented metastatic disease from the primary acral tumor. The primary tumor was focally positive for immunoreactivity to ferritin antibody, an immunohistologic marker for sweat gland malignancies. Ferritin antibody may prove useful in the diagnosis of aggressive digital papillary adenoma (ADPA) and ADPAca.