Schwannoma of the orbit.

Schwannoma of the orbit is an encapsulated, benign, noninvasive, slow-growing nerve sheath tumor which, when large enough, causes exophthalmos, optic neuropathy, diplopia, anterior orbital mass or sinusitis. An orbital schwannoma in a 84-year-old man with infiltration of the os spenoidale is reported. Schwannoma may arise anywhere within or adjacent to the orbit and is usually curable by local excision. The malignant counterpart, the malignant schwannoma, is exceedingly rare in the orbit. In orbital tumors many diagnostic steps are necessary, but the exact diagnosis is often determined only by histological examination. Schwannomas (synonyms neurilemoma, neurinoma) of the orbit are rare; they account for 1-6% of all orbital tumors. Here presented is a description of their appearance on clinical examination and on light and electron microscopy, together with a report on preoperative investigations and operative findings.