Plexiform pigmented schwannoma of the uvea.

Schwannoma is a slow growing solitary tumor that preferentially involves spinal nerve roots, and sympathetic, cervical, and vagus nerves. There are several clinico-pathologic variants of schwannoma, including schwannoma with a degenerative change (ancient schwannoma), cellular schwannoma, plexiform schwannoma, epithelioid schwannoma, and melanotic schwannoma. About 10% of cases of schwannomas are associated with multi-system disorders such as neurofibromatosis, schwannomatosis, multiple meningiomas, and Carney complex.