Eccrine syringofibroadenoma: the simultaneous occurrence of two histopathological variants (conventional and clear-cell type) in one patient

Solitary eccrine syringofibroadenoma with prominent plasma cell infiltration

Eccrine syringofibroadenoma (ESFA) is a rare, benign, adnexal neoplasm thought to be eccrine ductal differentiation displaying variable clinical findings and characteristic histological features. It usually occurs as a solitary nodule on the extremities of an elderly person. Histological findings typically show a proliferation of anastomosing strands, cords, and columns of monomorphous epithelial cells that harbor eccrine duct formations embedded in a fibrovascular stroma. Acrosyringial nevus, though usually regarded as an identical lesion, is sometimes regarded as a different entity showing prominent plasma cell infiltration. We report two cases of solitary ESFA with prominent plasma cell infiltration. Clinicopathological features of both cases suggest that acrosyringeal nevus and ESFA may be of the same disease entity. Prominent plasma cell infiltration may be just one of the common histological features of ESFA.

Eccrine Syringofibroadenoma of Clear Cell Variant

Eccrine syringofibroadenoma is a rare eccrine tumor first described by Mascaro in 1963. The clear cell variant was reported by Fretzin in 1995. We describe a hemorrhagic papule on the knee of a 64-year-old woman. Microscopic examination revealed epidermal-based anastomosing thin epithelial cords with ductal structures surrounded by a fibrovascular stroma. Multiple nests of glycogen-containing clear cells were also present. The tumor cells forming the epithelial cords expressed keratin. The eccrine ductal structures and clear cells additionally expressed gross cystic disease fluid protein-15 (GCDFP-15). Reactivity with antibodies against estrogen receptor or progesterone receptor was negative. These results favor the dual differentiation of the clear cell variant of eccrine syringofibroadenoma toward ductal and secretory portions of the eccrine sweat gland.