The nodular form of polymyositis--a possible manifestation of vasculitis.

A case of the nodular form of polymyositis is reported in which muscle necrosis and inflammation, and fibrosis of subcutaneous fat were observed. Although the patient had a short history, the presence of extensive fibrosis with acute lesions indicated that the disease had been present for some time. In addition to the nodular lesions, the patient had clinical, electrophysiological and pathological evidence of a more generalised myopathy. The subsequent development of a rash resembling that of vasculitis and a peripheral nerve lesion, suggested that the localised nodular myositis was associated with systemic vasculitis. Although immunoglobulin and complement deposits were not detected in blood vessel walls in muscle or skin, a positive reaction to intradermal injection of autologous serum suggested the presence of circulating immune complexes.