Membranous lipodystrophy of bone.

A 23-year old man with a fracture of the right lateral malleolus was found to have osteolytic lesions of the lower end of both fibulas and of the right talus. He was mentally defective from birth, with convulsions from the age of 4 years and a limp since the age of 15. Biopsy tissue from the right fibula that was removed one year after the fracture consisted of marrow adipose tissue that had been transformed by the development of thick, convuluted PAS positive membranes around the cells. Electron microscopy indicated that each membrane had a complex, microvillous substructure. At the time of biopsy, lytic lesions were found in both femoral medial condyles and, one year later, in the distal shaft of the left radius. Membranous lipodystrophy is a rare, generalized, skeletal disease that was previously reported in Finland and Japan, and is usually followed by progressive presenile dementia.