18F-FDG PET/CT Findings in a Case of Primary Leptomeningeal Melanomatosis With Diastematomyelia

Primary leptomeningeal melanomatosis is a rare and aggressive variant of primary central nervous system melanoma. Diagnosis is often challenging due to nonspecific radiologic features. We hereby report the 18F-FDG PET/CT and MRI findings in a case of primary leptomeningeal melanomatosis in a 47-year-old woman with a previously unidentified diastematomyelia. Spinal MRI showed diffuse abnormal signal. 18F-FDG PET/CT showed hypermetabolism most notably in the lumbar and caudal portion of the spinal cord, which was helpful to identify an appropriate site for biopsy.