The inflammatory myopathies have diverse clinical and pathological features and multiple etiologies. Some are confined to a single muscle or group of muscles (e.g., orbital myositis and localized nodular myositis) while others are diffuse. Infective forms may be due to viral, bacterial, fungal, protozoal, or parasitic organisms. Viruses may cause acute self-limited forms of myositis and have been isolated from muscle in some cases of acute rhabdomyolysis and inclusion body myositis. They have also been implicated in some cases of congenital myopathy and in polymyositis and dermatomyositis, but there is no evidence of viral invasion of muscle in these conditions. In polymyositis and dermatomyositis there are derangements in humoral and cellular immune function, and recent evidence suggests an underlying disturbance of immunoregulation. The roles of genetic factors, drugs, and Toxoplasma infection have been under scrutiny. There is increasing recognition of immunological and pathological differences in polymyositis and juvenile and adult dermatomyositis, and in cases with associated connective tissue diseases, suggesting different underlying pathogenetic mechanisms. Inclusion body myositis, eosinophilic myositis, and granulomatous myositis can be separated from the other idiopathic inflammatory myopathies because of distinctive clinical and pathological features and this may also reflect different mechanisms of muscle injury. Recent developments in the treatment of the idiopathic inflammatory myopathies include the use of plasmapheresis and total-body irradiation in cases that are resistant to corticosteroids and immunosuppressive drugs.

The clinical and myopathological features of 13 patients with a myopathy occurring in association with hypothyroidism are presented. Seven patients had hypothyroid myopathy, including two with the Hoffmann syndrome and one with the Kocher-Debre-Semelaigne syndrome. Five patients had an inflammatory myopathy and one had polymyalgia rheumatica. Serum CK activity was elevated up to 12-fold in the patients with hypothyroid myopathy and returned to normal after treatment with thyroxine. Pathological changes in these cases included type 1 or type 2 fibre atrophy or hypertrophy, myofibre necrosis and regeneration in four cases and, in one case, prominent core-like areas containing amorphous granulo-filamentous material. The findings in this series of cases illustrate the clinical and histopathological heterogeneity of patients with hypothyroid myopathy and the need to consider other myopathies in hypothyroid patients who present with muscular symptoms.

Idiopathic Inflammatory MyopathiesPobmyositis and Dermutomyositis (continuation from Part I ) DIAGNOSIS. The diagnosis of polymyositis (PM) and dermatomyositis (DM) poses few problems when clinical findings are typical, serum creatine kinase (CK) levels are elevated, electromyography (EMG) shows multifocal myopathic changes with spontaneous potentials, and muscle biopsy confirms the presence of a necrotizing inflammatory process. However, in patients with atypical clinical features and normal enzyme levels, or in whom EMG and biopsy findings are normal or show inconclusive changes, a diagnostic system based on certain major clinical and laboratory criteria can be useful. The criteria listed below are based on those originally proposed by Bohan and Peter 1 191 and as From the Address "Part 1 was published in the March issue of Annals ofNeuvolog~ (17:215-227). Abstract and references are contained in Part 1. Dr 317 Mathews MB, Reichlin M, Hughes GRV, Bernstein RM: Antithreonyl-tRNA synthetase, a second myositis-related autoantibody. J Exp Med 160:420-434, 1984 Reichlin M, Maddison PJ, Targoff I, et al: Antibodies to a nuclear/ nucleolar antigen in patients with polymyoritis overlap syndromes.

Two cancer patients had extensive spinal cord necrosis at necropsy. One had carcinoma of the breast and the other, carcinoma of the lung. Case 1 was treated by mastectomy, systemic chemotherapy and cranial irradiation, where as Case 2 received local irradiation to the right upper chest and right supraclavicular zone. In both cases, the spinal cord necrosis affected grey and white matter along most of its extent. Neither local nor systemic causes to explain the spinal cord lesion were disclosed at necropsy. It is suggested that these are two new examples of paraneoplastic necrotizing myelopathy. There are 22 such cases in the English language medical literature since 1903. Cancer 53:1115‐1123, 1984.

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