Meningeal melanocytoma

Abstract

Meningeal melanocytomas are rare tumors of the central nervous system that are found almost exclusively in the posterior fossa and spinal cord and whose natural history is poorly defined. In this report, the authors review the clinical presentation, radiological appearance, operative findings, and histological features in two cases of meningeal melanocytoma: one cranial and one spinal. Two women, aged 21 and 30 years, were admitted to the hospital 60 years apart: the first because of progressive paraplegia and the second because of slowly progressive hearing loss. The first patient had an extradural tumor that was treated by laminectomy, subtotal resection, and postoperative radiotherapy in 1936. Her symptoms recurred 16 years later and she underwent reoperation of the residual tumor, which was found to have an intradural component. The authors' patient, who presented 60 years later, underwent plain and enhanced computerized tomography and magnetic resonance imaging that demonstrated a large posterior fossa lesion indicative of either an acoustic neuroma or a meningioma. She underwent posterior fossa decompression but only partial excision of the tumor could be accomplished because vigorous bleeding limited the extent of the resection. Surgery was followed by radiotherapy. The residual tumor enlarged despite these measures and required repeated resection 6 months later. At the second operation the tumor was much less vascular, perhaps reflecting the effects of radiotherapy, and was removed almost entirely. The patient died 6 months later from an anticoagulant-related cerebellar hemorrhage. In both cases the lesions were jet black, and histological examination revealed melanin-containing hypercellular tumors with rare mitotic figures. Meningeal melanocytomas are being diagnosed with increased frequency in parallel with improvements in neuroimaging and clarification of histological features. Clinical presentation of patients with these tumors typically occurs in their fifth decade and women are affected twice as often as men. The posterior fossa lesions can mimic acoustic neuromas and meningiomas in location and radiological appearance; however, the internal auditory canal is normal. In the spine, meningeal melanocytomas present with the clinical features of myeloradiculopathy. Diagnosis is made intraoperatively from the gross, jet-black appearance of the tumor and from histological examination. Vascularity, size, and location may render complete resection unfeasible. Because of the tumor's propensity to recur, radiotherapy has been recommended but its role remains to be elucidated.

Benign Melanocytic Tumor in Infancy: Discussion on a Rare Case and Review of the Literature

“…These tumors are believed to develop from leptomeningeal melanocytes, and they closely resemble the other melanocytic neoplasms of the CNS. Differential diagnosis includes the pigmented meningioma, melanotic schwannoma, primary or secondary malignant melanoma and MNTI [5, 11, 13, 14, 17, 19, 20, 21, 22, 23]. The common derivation of the respective cells of these tumors from neural crest precursors may result in difficulties in distinguishing them.…”

“…The strong reactivity to S-100 protein and HMB-45 (antimelanoma antibody: a specific marker for melanocytes), but the negative response to glial fibrillary acidic protein, neuron-specific enolase and epithelial membrane antigen are the common findings [5, 13, 14, 17, 19, 21, 23, 24, 44]. Vimentin reactivity indicates the existence of cytoskeleton in the neoplastic cells and was observed frequently [5, 14, 17, 20, 21, 24, 33, 44]. However, the negative response to vimentin was also reported [11].…”

“…By depending on the propensity to cell type, these cells may include various amounts of cytoplasm and melanin pigment [5, 14, 19, 23, 32], and usually a large nucleus with prominent nucleoli [5, 11, 14, 17, 18, 46]. Necrosis and hemorrhage are usually absent, but presence of rare mitotic figures is frequently reported [12, 14, 18, 19, 21, 23, 24]. Slight tendency to whorl formation is an occasional finding [13].…”

“…The close similarity of these rare lesions to other melanotic CNS tumors limits the efficacy of standard diagnostic procedures and requires more extensive histopathological analysis. The prognosis of meningeal melanocytoma is usually good, but local aggressive behavior has been recorded frequently, particularly in those located on the midline since the dural sinuses limit the extent of surgery [11, 13, 14, 15, 16, 17, 18]. …”

Intracranial Meningeal Melanocytoma: Review of the Literature

“…These tumors are different in biological behavior, treatment and prognosis. Valenti was the first to describe pigmented cells normally found in the leptomeninges [1]. Limas and Tio, with their electron microscopic studies, demonstrated that the cell of origin of the so-called pigmented meningiomas is the melanocyte and not the meningothelial cell [2].…”