Paraganglioma of the vulva.

A case of vulvar paraganglioma is reported. Following presentation with vulvar pain, a 1-cm nodule was excised from the labium minus of a 58-year-old woman. Histologically, the tumor was composed of nests of round eosinophilic cells with moderately pleomorphic nuclei, beneath an intact squamous epithelium. Ultrastructural studies indicated two cell types within the neoplasm: chief cells with numerous small neurosecretory granules and peripheral slender sustentacular cells. A reticulin stain confirmed the "zellballen" nature of the neoplasm, and the neoplastic cells showed moderate argyrophilia on a Grimelius stain. The immunoperoxidase stains for chromogranin and neuron-specific enolase were strongly positive in the neoplastic chief cells. Immunostaining using anti-S-100 antibody confirmed the finding of sustentacular cells by identifying many slender cellular processes among the chief cells. These light and electron microscopic findings are diagnostic of paraganglioma, an entity not previously reported in the vulva to our knowledge.