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Primary hemorrhagic intramedullary melanoma. Case report with emphasis on the difficult preoperative diagnosis.

Primary melanoma of the central nervous system (CNS) is rare and primary spinal melanoma (PSM) is even more unusual. Preoperative diagnosis of melanocytic lesion as a PSM is difficult, because of the heterogeneous magnetic resonance (MR) signal intensity, due to hemorrhagic foci and melanin deposits. We describe the case of a 68 year-old male with a MR showing at Th8-Th9 level a well-defined intramedullary lesion; for the characteristics of hemorrhagic signal on MR and its association with a presumptive brain cavernoma, a preoperative diagnosis of intramedullary cavernous angioma was suspected. Pathological examination revealed a melanoma, and for the absence of other localizations outside the spinal cord, a diagnosis of primary spinal melanoma was established. The growth of PSM is slower and survival is longer than in the most common spinal metastasis from skin melanoma. Patients who undergo surgical excision, alone or associated with additional treatments, often show a long survival. We report this case to underline the importance and difficulties concerning the preoperative diagnosis of a hemorrhagic intramedullary lesion.