Meningeal melanocytosis in a young patient--an autopsy diagnosis.

Primary diffuse leptomeningeal melanocytosis is a very rare form of brain tumor. We report on a rapidly fatal case in an 18-year-old man presenting with symptoms and imaging features suggestive for subarachnoid hemorrhage or meningitis. The laboratory findings and imaging examination were still confusing and the diagnosis remained unclear during the patient's life. Autopsy was the cornerstone in disclosing the lesion, confirming its usefulness in the assessment of such unusual cases. The complete profile of the tumor was obtained only by histology and immunohistochemistry. Clinicians and pathologists must be aware of diagnosis difficulties in this rare disease which can represent a serious challenge in clinical practice.