Autoimmune disorders are common in hepatitis C virus (HCV) infection, and may be due to dysfunction of both cell and humoral immunity.1 HCV infection has therefore been associated with essential cryoglobulinaemia, polyarteritis nodosa, leucocytoclastic vasculitis, glomerulonephritis, and idiopathic pulmonary fibrosis.2 ,3 Polymyositis (PM) and dermatomyositis (DM) have more rarely been reported during the course of HCV infection.3-7 Previous authors have suggested that HCV infection might be responsible for the formation of autoantibodies and circulating autoimmune complexes, leading to PM/DM manifestations.2 ,3 We observed a new case, which is of particular interest, as the patient with PM and cranial neuropathy developed chronic active autoimmune hepatitis and HCV infection.

A 48 year old woman presented in March 1997 with a five month history of generalised muscle weakness and myalgia associated with dysphagia. She had no previous medical history. Examination showed muscle weakness affecting both arms and legs. Muscle power was gauged for eight proximal muscles (that is, neck flexors, trapezius, deltoid, biceps, psoas, maximus and medius gluteus, and quadriceps) by a modification of the British Medical Research Council grading system, resulting in scores ranging from 0 to 11 (theorical maximum score 88 points). Muscle …