Unexpected IgA nephropathy during the treatment of a young woman with idiopathic dermatomyositis: case report and review of the literature.

This article reports the unexpected discovery of IgA nephropathy in a 26-year-old Chinese woman 1.5 years after the onset of idiopathic dermatomyositis. The patient was taking immunosuppressive agents, prednisolone 25 mg and azathioprine 75 mg daily. Glomerulonephritis associated with idiopathic polymyositis/dermatomyositis is rare. A review of the medical literature indicates that the most common pattern seen in idiopathic polymyositis is mesangial proliferative glomerulonephritis. However, both membranous and mesangial proliferative glomerulonephritis are often seen in idiopathic dermatomyositis. It is still not clear, however, whether the humorally- mediated immune process in dermatomyositis and the cell-mediated immune process in polymyositis can explain the different patterns of occurrence of glomerular lesions in these two closely related disease entities.