Primary Diffuse Leptomeningeal Melanomatosis of Spine: 18F-FDG PET Findings.

Primary diffuse leptomeningeal melanomatosis is a rare variant of malignant melanoma of the central nervous system, arising from melanocytes of leptomeninges. It may involve leptomeninges and may invade brain superficially. The diagnosis of the disease with conventional imaging techniques is quite difficult. This case demonstrates the F-FDG uptake of primary diffuse leptomeningeal melanomatosis matching with MRI contrast enhancement regions particularly in the lower thoracic and superior lumbar region.