Eccrine porocarcinoma: Report of a case with fine needle aspiration cytology, histopathology and immunohistochemistry.

Background: Although relatively rare, eccrine porocarcinoma (EP) is widely recognized in the literature as the most common of the sweat gland adenocarcinoma types. EP is an adenocarcinoma of the eccrine sweat gland with a propensity to recur locally and metastasize to regional lymph nodes. This paper presents the second case of fine needle aspiration (FNA) cytology of an EP along with histopathology and immunohistochemistry.

Case: A 64-year-old Filipino woman had a history of EP of the right eyebrow and presented with a right preauricular mass. The cytopathologic features of the case included: (1) clusters and sheets of polyhedral epithelial tumor cells with abundant, cyanophilic, vacuolated cytoplasm; round to oval, hyperchromatic nuclei; and occasional prominent nucleoli; (2) multinucleated tumor cells; (3) singly dispersed and relatively large aggregates of parakeratotic squamous cells; and (4) a background of necrotic debris.

Conclusion: EP is crucial to developing an effective (curative) surgical plan. FNA cytology potentially provides a convenient, safe and effective approach to solving a challenging differential diagnosis. The constellation of cytologic findings probably is distinctive and, in the proper clinical setting, may be diagnostic. History is important in making an accurate diagnosis.