Brain Pathology Case of the Month - December 2013


Intradural Melanocytoma


Melanocytomas in the central nervous system are rare pigmented tumors that originate from leptomeninges. There have been 60 reported cases thus far in literature, of which about one third were found in spinal cord and remaining were intracranial mainly in the posterior fossa. The differential diagnosis of a solitary pigmented tumor in the spinal cord includes melanocytoma, pigmented schwannoma and malignant melanoma. Solitary melanocytic lesions in the central nervous system range from a histologically benign melanocytomas to highly aggressive malignant melanomas. Spinal melanocytomas mostly occur in the cervical or thoracic spine and usually present as intradural and extramedullary lesions on imaging. (1, 4, 6) Melanocytic neoplasms form a continuum from a well-differentiated melanocytoma to frankly malignant melanoma. Melanocytomas are discrete, non-infiltrative tumors composed of bland spindle or oval shaped cells with variable melanin content and without cytologic atypia or mitoses. However like other melanocytic tumors, they are immunoreactive to HBM-45 and S-100 protein but not to EMA (epithelial membrane antigen). (5) The classic electron microscopic features include presence of numerous melanosomes within spindle shaped cells. (1) This is particularly helpful in differentiating melanocytomas from melanotic schwannomas. Although melanocytoma is known as a benign tumor and the optimal treatment is complete resection (4), a close follow-up after surgical resection is necessary as recurrence remains an issue and it has been reported in the past. (2, 3)


  1. Brat DJ, Giannini C, Scheithauer BW, Burger PC (1999) Primary melanocytic neoplasms of the central nervous system. Am J Surg Pathol 23:745-754
  2. Eskandari R, Schmidt MH (2010) Intramedullary spinal melanocytoma. Rare Tumors 2:e24.
  3. Horn EM, Nakaji P, Coons SW, Dickman CA (2008) Surgical treatment for intramedullary spinal cord melanocytomas. J Neurosurg Spine 9:48-54
  4. Karikari IO, Powers CJ, Bagley CA, Cummings TJ, Radhakrishnan S, Friedman AH (2009) Primary intramedullary melanocytoma of the spinal cord: case report. Neurosurgery 64:E777-778.
  5. Liubinas SV, Maartens N, Drummond KJ (2010) Primary melanocytic neoplasms of the central nervous system. J Clin Neurosci 17:1227-1232.
  6. Shanthi V, Ramakrishna BA, Bheemaraju VV, Rao NM, Athota VR (2010) Spinal meningeal melanocytoma: A rare meningeal tumor. Ann Indian Acad Neurol 13:308-310.

Contributed by Ali Mahta, MD, Ewa Borys, MD, Scott R. Vandenberg, MD, PhD, Bob Carter, MD, PhD, Santosh Kesari, MD, PhD

International Society of Neuropathology