Meningeal melanocytoma: an aggressive course for a benign tumor

Abstract

A 79-year-old female presented with difficulty ambulating and was found to have weakness and hyperreflexia in the lower extremities. Magnetic resonance imaging (MRI) revealed a large T8-T9 intraspinal tumor. She underwent a thoracic laminectomy, and excision of an intradural extramedullary lesion. The surgical specimen was soft, black tissue that consisted of a moderately cellular, deeply pigmented tumor. The neoplastic cells proved to be melanocytic, and were devoid of overt features of anaplasia, i.e., prominent nuclear pleomorphism, necrosis, significant mitotic activity, and high proliferation indices. Four months postoperatively, MRI demonstrated focal areas of enhancement in the conus medullaris and in the fourth ventricle, indicating leptomeningeal spread. Subsequently, the patient underwent whole brain radiation. On repeat imaging, there was nodular enhancement of the fourth ventricle and throughout the spinal cord. Despite chemotherapy and radiation therapy, the disease advanced and the patient expired. Meningeal melanocytoma is a rare, histologically benign tumor with good prognosis. However, local aggressive behavior has been recorded, especially in cases of subtotal gross resection. On a literature review, there was one case of cranial posterior fossa meningeal melanocytoma with associated lesions in both suprarenal glands and the left kidney, but there were no cases with distant metastasis. In this report, we present an unusual case of spinal meningeal melanocytoma with diffuse spread throughout the craniospinal axis that proved to be fatal.