MR imaging findings of the uveal schwannoma

Abstract

Background and Purpose: Uveal schwannoma is a rare benign neoplastic proliferation of pure Schwann cells. The purpose of this study was to describe MR imaging features of uveal schwannoma. MATERIALS AND METHODS: MR images in 6 female patients with uveal schwannoma confirmed by pathologic examination were retrospectively reviewed. MR imaging was performed in all 6 patients, with postcontrast T1-weighted imaging (T1WI) completed in all 6 patients and dynamic contrast - enhanced MR imaging, in 5. MR imaging findings of the tumor were evaluated with emphasis on the location, size, shape, margin, signal intensity, and pattern of enhancement. Results: The lesions appeared as solitary well-defined ovoid masses in the ciliochoroidal region in 5 patients and in the choroid in 1. With respect to the vitreous body, uveal schwannoma was hyperin - tense on T1WI spin-echo (SE) images in all 6 patients. The tumors were hypointense to the vitreous body on fast SE (FSE) T2-weighted images (T2WI) in 4 patients and isointense in 1. However, with respect to the brain, uveal schwannoma demonstrated isointensity on T1WI SE images in all 6 patients, isointensity on FSE T2WI images in 5 patients, and hyperintensity on T2WI SE images in 1. On postcontrast T1WI images, 3 patients showed markedly heterogeneous enhancement, and 3 showed markedly homogeneous enhancement. Conclusions: Uveal schwannoma should be included in the differential diagnosis when an oval isointense mass relative to brain is seen in the ciliochoroidal region.