APOCRINE MIXED TUMOR OF THE SKIN WITH FOL LICULAR DIFFERENTIATION

An 85-year-old man presented with a firm, papillomatous nodule on the upper lip, which had been growing slowly for 30 years. Histopathologic examination revealed an apocrine mixed tumour with follicular differe ntiation. Mixed tumors of the skin are rare benign neoplasms, which ar e composed of different tissue components, e.g. epithelial and glandul ar elements and myxoid or chondroid components. Mixed tumors with apoc rine differentiation can be discriminated from mixed tumors with eccri ne differentiation. Criteria for apocrine differentiation are: decapit ation secretion, elongated gland-like and duct-like structures lined w ith two rows of epithelial cells and branching of tubular structures. Follicular structures are another clue to the apocrine differentiation of neoplasms. The designation mixed tumour is preferable to chondroid syringoma, because most mixed tumours show apocrine differentiation. The differential diagnosis of apocrine mixed tumour includes fibroaden oma, hidradenoma, mucinous adenocarcinoma, adenoid cystic carcinoma, a nd rare soft tissue tumours like the myxoid chondrosarcoma.