Plexiform schwannoma of the clitoris in a young girl: a case report.

BACKGROUND: Schwannoma (neurilemoma) is a benign, slow-growing tumor of the nerve sheath. These tumors are rarely found in the female genitalia and to date only 1 case of clitoral schwannoma has been reported in a young girl. We report here the second case of schwannoma of the clitoris.

CASE: A 6-year-old girl presented with an enlarging clitoris. An alteration in her clitoral appearance had first been noted at 2 years of age. However, the size had further increased in the year prior to presentation. On examination her clitoris was normal in size but beneath the clitoral hood, predominantly on the left, there was a 3 x 2 cm irregular mobile mass. Her karyotype revealed normal 46XX female genotype. Magnetic resonance imaging of the abdomen and pelvis showed an isolated finding of diffuse enlargement of the clitoris with edema of the mons pubis. Surgical excision of the paraclitoral mass was performed. Intraoperatively the clitoral tip and shaft did not appear to be involved. However, the mass was found to be more diffuse, less well-defined, and more extensive than the clinical findings had suggested. On histology long spindle cells with nuclear palisading and focal Verocay body-like structures were found. There was mild to moderate pleomorphism. No mitotic figures were identified. There was diffuse staining of interweaving bundles for S100 protein and glial fibrillary acidic protein without staining for actin, desmin, or neurofilament. These features are consistent with a plexiform schwannoma.

CONCLUSION: Although benign schwannomas rarely occur in the clitoris, we suggest that it should be considered as differential diagnosis for any young girl with clitoral or paraclitoral asymmetrical irregular mass.