Crescentic glomerulonephritis associated with nonrenal malignancies^1,2

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 < 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.