Eccrine porocarcinoma of the vulva: a case report and review of literature.

A case of a 48-year-old woman with a 5 cm left vulvar mass that grew over a six month period is presented. Histopathologic examination of the excised mass was diagnostic of malignant eccrine poroma (eccrine porocarcinoma) with in-situ component. Due to the rarity of this tumor (only five vulvar cases previously reported) and its heterogeneous non-specific clinical and histologic features, the tumor often presents as a diagnostic challenge to clinicians and pathologists. The tumor may be mistaken for a metastasis in cases where the tumor cells are poorly differentiated or for a squamous cell carcinoma in cases with extensive squamous differentiation. There is a need for correct diagnosis of this rare entity - so that appropriate therapy can be instituted in a timely manner. The pertinent literature is reviewed highlighting the diagnostic histomorphologic features and the immunohistochemical profile for making the correct diagnosis of eccrine porocarcinoma.