A case of diffuse endocapillary proliferative glomerulonephritis associated with polymyalgia rheumatica.

A 70-year-old man complained of muscle pain in his neck, shoulders and pelvic girdle. Proteinuria and hematuria subsequently developed. Blood analysis showed increased acute phase reactants. The histology of renal biopsy showed diffuse endocapillary proliferative glomerulonephritis. There were no signs of autoimmune diseases, malignancies and bacterial or viral infections. His extrarenal symptoms and the results of blood analysis fulfilled three different criteria of polymyalgia rheumatica (PMR). Therefore, diffuse endocapillary proliferative glomerulonephritis associated with PMR was diagnosed. After low-dose prednisolone (10 mg/day) treatment, the muscle pain disappeared, acute phase reactants decreased and hematuria and proteinuria improved. The renal complication of PMR is rare but important to be considered early in the right clinical context.