Idiopathic polymyositis complicated by arthritis and mesangial proliferative glomerulonephritis: case report and review of the literature.

A 56-yr-old male developed a systemic illness while receiving cyclical oral etidronate therapy for idiopathic osteoporosis. The illness, characterized by fever, proximal myopathy and inflammatory synovitis, was associated with interstitial lung disease and mesangial proliferative glomerulonephritis. Elevated plasma creatine phosphokinase level and inflammatory muscle biopsy findings confirmed a diagnosis of polymyositis (PM). Antibodies to Jo-1 were also detected. A review of the literature reveals that mesangial proliferation is the commonest glomerular lesion and suggests a possible association between arthritis and glomerulonephritis in PM. The prognosis of this renal lesion appears to be good, although only limited data is available.