Peripheral primitive neuroectodermal tumor of the vulva: report of a case with imprint cytology

Peripheral primitive neuroectodermal tumor (PNET) of the vulva is an extremely rare disease, and, to our knowledge, only two cases have been previously reported.

A 45-year-old woman presented with a mass in the right labium major. Three years after removal of the tumor, she noticed a new lesion in the same place and underwent a partial vulvectomy. The imprint cytology of the recurrent tumor showed a monomorphic appearance, composed of small round cells with scant cytoplasm against a hemorrhagic background. These tumor cells were loosely connective, but rosettelike structures were observed focally. On pathologic examination, the neoplasm was composed of small round tumor cells showing sinusoidal, diffuse or micropapillary growth. Immunohistochemically, the neoplastic cells stained positively for neuron-specific enolase, vimentin and HBA 71 and negatively for cytokeratin, HBA 45 and muscle-specific actin. The morphologic characteristics of the disease were well expressed in the imprint cytology, and this influenced the selection of immunohistochemical studies.

Cytologic examination for vulvar tumors, even imprint cytology, can be a useful tool in obtaining an accurate pathologic diagnosis of a rare disease, such as peripheral PNET.