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Choroidal schwannoma: immunohistochemical and electron-microscopic study
1Department of Ophthalmology, Okayama University Medical School, Okayama City, Japan. matsuot@cc.okayama-u.ac.jp
Summary
Intraocular schwannoma, a rare tumor of the ciliary body and choroid, is often misdiagnosed as amelanotic melanoma. This case highlights the importance of histopathology for accurate diagnosis of this challenging intraocular tumor.
Area of Science:
- Ophthalmology
- Pathology
- Oncology
Background:
- Intraocular tumors, particularly those of the ciliary body and choroid, present diagnostic challenges.
- Schwannoma (neurilemoma) is a rare intraocular tumor that can mimic other malignancies.
- Accurate diagnosis is crucial for appropriate patient management and treatment strategies.
Observation:
- A case report details a 73-year-old woman with a large, nonpigmented intraocular tumor of the choroid.
- The tumor was clinically diagnosed as malignant melanoma and the eye was enucleated.
- Pre-operative imaging (fluorescein angiography, ultrasonography, MRI) did not exclude a diagnosis of choroidal melanoma.
Findings:
- Histopathological examination revealed a schwannoma, characterized by spindle-shaped cells with positive immunoreactivity for S-100 protein, vimentin, glial fibrillary acidic protein, and neural cell adhesion molecule.
- Immunostaining confirmed a continuous basal lamina, indicative of Schwann cell origin.
- Ultrastructural analysis showed tumor cells with delicate cytoplasmic processes, further supporting schwannoma diagnosis.
Implications:
- This case underscores the difficulty in clinically diagnosing intraocular schwannoma, often leading to misdiagnosis as amelanotic melanoma.
- There is a current lack of established clinical diagnostic benchmarks for intraocular schwannoma.
- Further research is needed to develop reliable methods for the pre-operative clinical diagnosis of intraocular schwannoma.