Case of the Week
Section Editors: Matylda Machnowska1 and Anvita Pauranik2
1University of Toronto, Toronto, Ontario, Canada
2BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
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March 7, 2016
Primary Melanoma of Cerebellopontine Angle
- Background:
- Primary CNS melanoma represents approximately 1% of all cases of melanoma.
- In the CNS, these lesions arise from melanocytes of the leptomeninges. Their localization within the cerebellopontine angle is rare, and the lesion is commonly mistaken for more typical tumors of this region, with the diagnosis usually made postoperatively.
- Clinical Presentation:
- In this location, the lesion may cause mass effect on cranial nerves V to XI, subarachnoid hemorrhage, cerebellar signs, or signs of brain stem compression.
- Key Diagnostic Features:
- Hyperdensity with homogeneous enhancement on CT.
- Hyperintensity on T1, iso/hypointensity on T2, hypointensity on T2*, and homogeneous enhancement.
- Cutaneous or mucosal/retinal melanoma must be ruled out to exclude the possibility of a metastatic lesion.
- Histopathologic and immunohistochemical confirmation is needed.
- Differential Diagnosis:
- Benign tumors: Schwannoma (melanotic variant), meningioma (melanotic variant), epidermoid cyst, neurenteric cyst
- Malignant tumors: Metastasis
- Treatment:
- Resection of the tumor, followed by radiotherapy