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Intramedullary Intermediate Melanocytoma with Leptomeningeal Metastases 2012

General Spine

Michael, E., Seymour, M.D.
Lisa, I., Yang, M.D., Non ASSR Member
David, P., Chason, M.D., Non ASSR Member
Carlos, L., Perez, M.D., Non ASSR Member

Excerpta

Primary melanocytic neoplasms of the central nervous system are rare, most commonly extramedullary, and represent a continuum ranging from histologically benign melanocytomas to overtly malignant melanoma.

Purpose

To report a rare case of an intramedullary intermediate grade melanocytic neoplasm with leptomeningeal spread.

Methods & Materials

The clinical documents and imaging studies were reviewed.

Results

A 53 year-old male presented with a 4 month history of progressive weakness, abnormal sensation, and lack of coordination of the right lower extremity. MR showed a 13 mm intramedullary mass at the level of T9-10 with T1 shortening, enhancement, cord expansion, and adjacent cord edema. There was also a small focus of enhancement with T1 shortening along the cauda equina. The patient underwent gross total resection of the mass. Pathology showed a melanocytic neoplasm with monomorphic nuclei, rare mitoses, and a focally moderate MIB-1 index (which correlates with cellular proliferation). These findings are consistent with an intermediate melanocytoma. Radiation therapy was subsequently administered from T7-S3 to treat presumed leptomeningeal metastases. The patient has undergone continued MR surveillance for three years after gross total resection. There has been development and gradual enlargement of an intradural extramedullary enhancing lesion with T1 shortening at the level of T9. There has also been development of numerous enhancing nodular foci with T1 shortening along the surface of the spinal cord and cauda equina.

Conclusion

There are fewer than five prior reports of intramedullary intermediate melanocytomas. The slow progression of leptomeningeal metastases in our patient is consistent with the primary lesion's intermediate grade histology as opposed to the aggressive growth more commonly seen with melanoma. Our case further demonstrates the continuum of primary CNS melanocytic neoplasms which can sometimes be intramedullary in location and further emphasizes the need for continued follow-up imaging.

References/Financial Disclosures

El-Khashab M, Koral K, Bowers DC, Johnson-Welch S, Swift D, Nejat F. Intermediate grade meningeal melanocytoma of cervical spine. Childs Nerv Syst 2009;25: 407-410. Horn EM, Nakaji P, Coons SW, Dickman CA. Surgical treatment for intramedullary spinal cord melanocytoms. J. Neurosurg Spine 2008;9:48-54. Karikuri IO, Powers CJ, Bagley CA, Cummings TJ, Radhakrishnan S, Friedman AH. PrimaryIntramedullary Melanocytoma of the Spinal Cord: Case Report. Neurosurgery 2009;64:E777-E778. Paolo P, Caniglia M, Pieroni M, Castagna M, Parenti GF. Malignant Transformation of Intramedullary Melanocytoma: Case Report. Neurosurgery 2010;67:E867-E869. Financial Disclosures: None

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