Fig. 1From: Muscle biopsy features of idiopathic inflammatory myopathies and differential diagnosisPolymyositis (muscle biopsy, hematoxylin and eosin staining). a A small endomysial inflammatory infiltrate surrounding and invading a healthy muscle fiber. b Scattered necrotic and regenerating muscle fibers. c MHC class I antigen is expressed on the sarcolemma of almost all muscle fibersBack to article page