Segmental myofiber necrosis in myotonic dystrophy - An immunoperoxidase study of immunoglobulins in skeletal muscle.

Because serum immunoglobulin G levels are low in patients with myotonic dystrophy, it was hypothesized that it might be catabolized within abnormal muscle fibers. Accordingly, immunohistochemical stains for immunoglobulins were performed on muscle sections derived at biopsy or autopsy from patients with myotonic dystrophy, other forms of muscular dystrophy, nondystrophic muscle disease, or normal muscle. Positive staining for immunoglobulins was found only in necrotic segments of myofibers (in 7 of 19 dystrophic and 6 of 27 nondystrophic subjects), and it is believed that the staining was due to nonspecific diffusion. However, staining reactions distinguished between incipient necrosis and artifactual contraction bands and allowed us to study segmental myofiber necrosis, comparing its frequency in the various muscle diseases. Segmental myofiber necrosis was present in 4 of 16 cases of myotonic dystrophy. The relevance of this finding to the clinical and morphologic features of myotonic dystrophy is discussed.