Anomalies in perifascicular muscle fibers as an differential-diagnostic criterion. II. Perifascicular hypertrophies in primary myopathies.

In order to compare a group of patients with a polymyositis (PM) to a control group, 28 cases of primary myopathies were examined by morphometry with regard to differences between central and peripheral muscle fibers in muscle fascicles. A significant difference in favor of peripheral muscle fibers, i.e., a peripheral hypertrophy was found in 22 out 28 cases (significantly in 14 cases). Therefore, histometry is a valuable additional method for discrimination between PM and primary myopathies.