Lafora's disease: peroxisomal storage in skeletal muscle.

A 17-year-old patient had myoclonic epilepsy caused by Lafora's disease. Biopsy showed polysaccharide accumulations within membrane-bound spaces in skeletal muscle cells. Some of the accumulations were morphologically similar to Lafora bodies as they have been seen in the brain. The histochemical reactions of these membrane-bound spaces suggested that they were peroxisomes. Polysaccharide accumulations also were demonstrated in hepatic cells, where they probably were located in the endoplasmic reticulum. Lafora's disease can be diagnosed by histochemical and electron microscopic study of skeletal muscle.