Morphological and biochemical changes in muscle and peripheral nerve in Fabry's disease.

In a case of Fabry's disease, microscopic, ultrastructural, and biochemical studies of a muscle biopsy were performed, as well as microscopic, ultrastructural, and morphometric studies of a nerve biopsy. Pleomorphic lipid inclusions were observed in muscle fibers, fibroblasts, and endomysial capillaries. Moreover, the thermolabile isoenzyme A of alpha-D-galactosidase was almost completely absent. In the nerve specimen, polymorphous lysosomes were noted in perineural cells, in fibroblasts, and in endothelial and perithelial cells in association with some nonspecific degenerative changes. The morphometric data revealed a loss of large myelinated fibers, an uncommon finding in Fabry's disease, and a decrease of the average diameter of the unmyelinated fibers, which was related to axonal sprouting. The relationship between the pain attacks and the increased number of the small unmyelinated fibers is discussed.