Meningeal melanocytoma in the cerebellopontine angle: A rare case report and review of the literature

Abstract

Primary meningeal melanocytoma (MM) in the cerebellopontine angle (CPA) region is an extremely rare neoplasm that originates from the melanocytes in the leptomeninges. These lesions are usually misdiagnosed as they mimic other common CPA lesions through their nonspecific presenting symptoms, signs, and radiological characteristics. Here, we report a 47-year-old Chinese female patient who presented with a 1-month history of the right-sided tongue numbness and 1-week history of the right-sided face numbness that had been worsening for 2 days. The tumor, in the right CPA region, showed a slight isointensity on T1-weighted image and mixed signal intensity on T2-weighted image. The clinical presentation, surgical treatment, and pathologic characteristics were determined. The tumor was microsurgically resected and gross-total resection was achieved. The tumor revealed a solid, capsulated, brown-black lesion. Immunohistochemistry showed that the tumor cells were positive for human melanoma black-45 (HMB-45), melanoma antigen (MelanA), S100, SOX10, and BRAF, confirming the final diagnosis of meningeal melanocytoma. Ultimately, no signs of radiological local recurrence were observed during the two-year follow-up. Collectively, meningeal melanocytoma is difficult to distinguish from common tumors in the CPA region before operation due to the lack of specificity in imaging and symptoms. Complete surgical resection is the best therapeutic option for this tumor. Although the tumor is commonly considered as a benign lesion, recurrence and metastasis are common, and pathogenesis remains unclear.