Cutaneous meningioma.

Cutaneous meningioma is a rare tumor that most commonly occurs on the scalp and occurs in both congenital and acquired forms. It invokes a wide clinical differential diagnosis, but diagnosis is based on characteristic histologic and cytologic findings. Congenital lesions can often present years after birth and even in adult patients. Acquired lesions occur in adulthood. We review histologic, cytologic, and electron microscopic findings and explore how these are used to separate this entity from other entities in the differential diagnosis. While ultrastructural and cytologic findings are similar to those of more common intracranial meningiomas, these tumors exhibit a range of histologic differences. A lack of awareness of this entity precludes correct diagnosis.