Tubulomembranous and fingerprint-like inclusions in biopsied muscle of distal myopathy with rimmed vascuoles

Summary

Muscle biopsies from four patients were studied histochemically and electron-microscopically: they had myopathy of juvenile or early-adult onset, in which distal limb muscles were most severely affected but muscles supplied by cranial nerves were spared. Common histochemical findings included variation in fiber size, necrosis, phagocytosis, fiber splitting, central nuclei, endomysial fibrosis, and particularly rimmed vacuoles. Electron-microscopic examination revealed frequent autophagic vacuoles with numerous myeloid bodies. In addition, sarcoplasmic inclusion bodies with periodically laminated structures similar to the tubulomembranous structures (TMSs) first described by Fukuhara et al. (1981) in an atypical myopathy were found in all four cases, and in one, there were fingerprint-like structures resembling those described in neuronal ceroid-lipofuscinoses. These inclusions occasionally contained areas resembling lipofuscin pigment. They are certainly residual bodies of lysosomal origin, which might be related to the rimmed-vacuolar degeneration of the muscle, but whether or not they represent some specific metabolic abnormalities seems to remain an open question since the present cases differed clinically from either of the atypical myopathies with TMSs (Fukuhara et al. 1981) or any type of neuronal ceroid-lipofuscinosis.