Meningeal melanocytoma of Meckel's cave associated with ipsilateral Ota's nevus.

A case of meningeal melanocytoma of the left Meckel's cave associated with ipsilateral Ota's nevus in a 43-year-old woman, was studied by light and electron microscopy. The cells of the tumor were characterized by the presence of dendritic cytoplasmic processes, melanosomes and premelanosomes; hence, they were deemed as neoplastic melanocytes. Moreover, the tumor was lacking in histologic and ultrastructural features of pigmented meningioma, melanotic Schwannoma and primary meningeal melanoma. The prolonged clinical course was different from primary and metastatic malignant melanomas of the meninges. The best treatment appears to be radical excision, when possible; otherwise, the local or partial enucleation followed by radiation therapy has been found to be the best curative to date. On the whole, meningeal melanocytoma cannot be considered as entirely benign, given its morphologic patterns that resemble those of uveal melanoma, and its potential for recurrence. The association of this tumor with Ota's nevus is referred to as having a common origin from an arrested migration of melanoblasts at different stages.