Crescentic glomerulonephritis associated with nonrenal malignancies.

A review of 80 patients with the renal biopsy diagnosis of idiopathic glomerulonephritis with extracapillary proliferation (crescentic GN) disclosed 7 cases with a coexistent nonrenal malignancy; 6 carcinomas and 1 lymphoma. In a control group of 80 patients with the renal biopsy diagnosis of minimal change or focal segmental glomerulosclerosis, only 1 case of coexistent malignancy was found (chi-square = 4.74, p less than 0.05). All of the malignancies occurred in patients older than 40 years of age and the prevalence of malignancy in patients with crescentic GN over the age of 40 was 20%. Light microscopy, immunofluorescence, and electron microscopy revealed fibrin deposition in all cases and no evidence of anti-GBM or immune complex disease. 3 patients experienced a rapidly progressive course while renal function improved in 4 patients following treatment of the underlying malignancy. The pathogenic mechanisms leading to crescentic GN in patients with malignancy are unknown; however, the high prevalence of malignancy in crescentic GN patients older than 40 along with the improvement during the treatment of the underlying malignancy suggests an etiological relationship.