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. Schwannoma rarely present as an intraocular tumor and is often misdiagnosed as malignant melanoma. Immunohistochemical positivity with S-100 stain and demonstration of long-spaced collagen (Luse bodies) are helpful in establishing the diagnosis. In this article, we review the clinical and histopathological findings of a sporadic plexiform pigmented schwannoma involving the iris, ciliary body, and the choroid.