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Year : 2008  |  Volume : 51  |  Issue : 1  |  Page : 47-48
Melanocytoma of cerebellum

Department of Pathology, Kasturba Medical College, Mangalore 575 001, Karnataka, India

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Melanocytomas are rare melanocytic tumors of the central nervous system. We report a rare case of melanocytoma in the cerebellum of a 35-year-old male patient. Computed tomography scan showed a cystic lesion with an enhancing solid component arising from the cerebellum. The lesion was resected and a histological diagnosis of melanocytoma of the cerebellum was made.

Keywords: Cerebellum, melanocytoma, gross, histopathology

How to cite this article:
Rai S, Sharma M, Naik R, Sinha R, Philipose R, Verghese R. Melanocytoma of cerebellum. Indian J Pathol Microbiol 2008;51:47-8

How to cite this URL:
Rai S, Sharma M, Naik R, Sinha R, Philipose R, Verghese R. Melanocytoma of cerebellum. Indian J Pathol Microbiol [serial online] 2008 [cited 2022 Dec 1];51:47-8. Available from:

   Introduction Top

Melanocytomas are rare pigmented tumors of the central nervous system (CNS). The term melanocytoma was first proposed in 1972 to describe a heavily pigmented foramen magnum tumor based on electron microscopic studies. [1] Clinically, the tumor occurs commonly in the fifth decade and is more common in females than males. The posterior fossa lesions mimic acoustic neuromas and meningiomas in location and radiologically. In the spine, the lesions usually present with myeloradiculopathy.

   Case History Top

We present a case of a 35-year-old male patient with generalized weakness, vomiting, disorientation, and hypotonia of both upper and lower limbs. Cerebellar signs could not be elicited. General physical examination did not reveal any organomegaly, lymphadenopathy, or cutaneous lesions. The CT scan showed a cystic lesion with an enhancing solid component arising from the cerebellum with proximal hydrocephalus. Intraoperatively, the posterior fossa was discolored black and on a cortical incision, a dark fluid followed by xanthochromic fluid was evacuated. A black, mildly vascular, well-circumscribed tumor measuring 1.5 cm was excised. Fragment of pigmented overlying dura and bone was also removed and sent for histopathologic examination.

Pathological findings

Grossly multiple grey-brown to black friable bits of tissue was received along with fragment of dura with attached bony bits.

Histologic examination showed proliferating tumor cells with moderate amount of eosinophilic to clear cytoplasm with centrally placed vesicular nuclei few showing prominent nucleoli. There was no nuclear pleomorphism, mitosis, or necrosis. Dense intracytoplasmic melanin pigment was present in the cells focally. Cells were arranged in sheets and tight clusters [Figure - 1]. The surrounding cerebellar tissue, overlying dura [Figure - 2] and bone also showed presence of melanin pigment. Melanin bleach confirmed the pigment as melanin and highlighted the nuclear features. Perls Prussian blue stain was negative.

   Discussion Top

Brat et al. [2],[3] had classified melanocytic lesions of CNS with respect to focal mass lesions as low grade (melanocytoma), intermediate grade, and high grade (melanoma). Few authors consider melanocytomas as a borderline tumor between cellular blue nevus and spindle melanoma. [1] The present World Health Organization classification classifies primay melanocytic lesions as diffuse melanocytosis, melanocytoma, malignant melanoma, and meningial malanomatosis. [4] Of these lesions, only melanocytomas and malignant melanoma present as solitary lesions.

The histological differential diagnosis for solitary pigmented lesions of the CNS includes melanocytoma, pigmented schwannomas, and malignant melano-mas. [3],[5]

Melanocytic schwannomas show compactly interwoven fascicles of pigmented spindle cells with oval nuclei. There can be mild nuclear pleomorphism with occasional mitosis [6] which was not seen in our case.

Malignant melanomas histologically consist of spindled or epithelioid cells arranged in loose nests, fasicles, or sheets with variable cytoplasmic melanin pigment. Tight nesting pattern is not a feature of malignant melanomas. [3] Nuclear atypia and pleomorphism is seen along with numerous mitotic figures, necrosis, and microscopic invasion which were not seen in this case. Primary CNS melanomas are solitary and arise from the leptomeninges. Metastatic melanomas present as multiple lesions confined to CNS or other organs and have a dismal prognosis. Patients usually present with a primary skin lesion or history of removal of primary melanoma. [3]

In view of the above findings, a diagnosis of an intracranial melanocytoma was considered.

Intracranial meningeal melanocytomas are slow growing tumors and present clinically with obstructive hydrocephalus, cerebellar dysfunction, and cranial nerve involvement with long-time patient survival following complete resection. [5] Spinal meningeal melanocytomas may be intradural or extradural and occur from cervical to thoracolumbar region. Patient presents clinically with radiculopathy with or without myelopathy. [5]

Grossly, melanocytomas are well-circumscribed, encapsulated, dark brown to black nodular tumors. Histologically, the cells are arranged in sheets, bundles, nests, and whorls surrounded by a fine network of reticulin fibers. The cells are fusiform to polygonal and epithelioid with abundant pale eosinophilic cytoplasm, and oval nucleus as seen in our case. Tight clustering of cells is also a feature of these tumors. [3] Intracytoplasmic melanin pigment is present within the cells and in the histiocytes surrounding or in the vicinity of blood vessels. [7] Prominent nucleoli have also been described by a few authors. [1],[7] Mitotic figures are rare or absent. Necrosis and hemorrhage are also not seen. [1],[5] We neither found any mitosis nor necrosis, but O'Brien et al. [8] has reported minimal necrosis. Psammoma bodies and calcification have also occasionally been reported. [1],[7]

The origin of these tumors is controversial. However, it is believed to arise from the melanocytes in the leptomeninges. These melanocytes occur in the highest concentration in the region ventrolateral to the medulla oblongata. This accounts for the common intracranial location of the melanocytomas in the cerebellopontine angle. [5]

Immunohistochemically, meningeal melanocytomas show positive cytoplasmic reactivity for S100 protein and vimentin. HMB45 and antimelanoma antibody are also strongly positive. Staining for keratin, epithelial membrane antigen (EMA), glial fibrillary acidic protein (GFAP), and neuron specific enolase (NSE) is nonimmunoreactive. [1],[5],[7]

   References Top

1.Ibanez J, Weil B, Ayala A, Jimenez A, Acedo C, Rodrigo I. Meningeal melanocytoma: Case report and review of the literature. Histopathology 1997;30:576-81.  Back to cited text no. 1    
2.Roser F, Nakamura M, Brandis A, Hans V, Vorkapic P, Samii M. Transition from meningeal melanocytoma to primary cerebral melanoma. J Neurosurg 2004;101:528-31.  Back to cited text no. 2  [PUBMED]  
3.Brat DJ, Giannini C, Scheithauer BW, Burger PC. Primary melanocytic neoplasms of the central nervous system. Am J Surg Pathol 1999;23:745-54.  Back to cited text no. 3  [PUBMED]  [FULLTEXT]
4.Ellison D, Love S, Chimelli L, Harding BN, Lowe J, Vinters HV, editors. Neuropathology-A reference text of CNS pathology. 2nd ed. London: Mosby; 2004.  Back to cited text no. 4    
5.Clarke DB, Leblanc R, Bertrand G, Quartey GRC, Snipes GJ. Meningeal melanocytoma: report of case and historical comparison. J Neurosurg 1998;88:116-21.  Back to cited text no. 5    
6.Ranjan A, Chacko G, Chandi SM. Intracerebellar melanocytic schwannoma: a case report. Brit J Neurosurg 1995;9:687-9.  Back to cited text no. 6    
7.Winston KR, Sotrel A, Schnitt SJ. Meningeal melanocytoma: case report and review of clinical and histological features. J Neurosurg 1987;66:50-7.  Back to cited text no. 7  [PUBMED]  
8.O'Brien TF, Moran M, Miller JH, Hensley SD. Meningeal melanocytoma. An uncommon diagnostic pitfall in surgical pathology. Arch Pathol Lab Med 1995;119:542-6.  Back to cited text no. 8    

Correspondence Address:
S Rai
Department of Pathology, Kasturba Medical College, Light House Hill Road, Mangalore 575 001, Karnataka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0377-4929.40394

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  [Figure - 1], [Figure - 2]

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