Polymyositis and dermatomyositis (first of two parts).

Adolescent Adult Age Factors Biopsy Child Child, Preschool Collagen Diseases/complications Dermatomyositis/classification,complications,diagnosis,pathology Diagnosis, Differential Female Humans Inflammation Male Middle Aged Muscles/pathology Myositis/classification,complications,diagnosis,pathology Neoplasms/complications,epidemiology Sex Factors Syndrome Vascular Diseases/complications