Giant superficial angiomyxoma of the vulva: a case report and review of the literature.

Superficial angiomyxomas (SAMs) are rare, benign cutaneous tumors frequently involving the subcutis. Only 15 cases of SAM involving the vulva have been reported, ranging from 0.9 to 4 cm in diameter. A 26-year-old woman presented with a 7-year history of a large, pedunculated cutaneous mass on the left labium major, measuring 12.5 x 11 x 10.5 cm and mimicking a soft tissue sarcoma. The mass was relatively well-circumscribed, but unencapsulated and multilobulated. Microscopically, the mass showed a conglomerate of moderately-to-sparsely cellular angiomyxoid lobules. Each lobule consisted of scattered spindle-shaped or stellate tumor cells set in an abundant myxoid stroma. Thin-walled, small-to-medium-sized blood vessels were distributed diffusely throughout the stroma. Scattered stromal neutrophils were also observed. No large vessels or plexiform capillaries were apparent. There was no perivascular accentuation of stromal cells or smooth muscle bundles. The tumor cells constantly expressed vimentin, CD34, CD44 and S-100, but none expressed estrogen receptors (ERs) and progesterone receptors (PRs), desmin or cytokeratin. Together, these findings were diagnostic of a SAM. Giant SAMs of the vulva can mimic aggressive angiomyxomas (AAMs) and angiomyofibroblastomas (AMB), as well as soft tissue sarcomas. Giant SAMs should be included in the differential diagnosis of vulvar soft tissue tumors.