Pauci-Immune Crescentic Glomerulonephritis due to Disseminated Histoplasmosis

When renal biopsy reveals crescentic glomerulonephritis, differential diagnosis is wide and includes 3 immunopathologic categories of disease: immune-complex–mediated glomerulonephritis (such as IgA nephropathy, lupus nephritis, and bacterial infection–associated glomerulonephritis, particularly infectious endocarditis-associated glomerulonephritis), anti–glomerular basement membrane nephritis, and pauci-immune crescentic glomerulonephritis (associated with antineutrophil cytoplasmic antibody seropositivity in most patients). Careful integration of immunofluorescence and ultrastructural findings with the serologic tests and medical history is essential to determine the underlying cause. Rarely, crescentic glomerulonephritis occurs concomitantly with granulomatous interstitial nephritis, and the differential diagnosis in this scenario includes granulomatosis with polyangiitis and sarcoidosis. Here we report an unusual case of pauci-immune crescentic and necrotizing glomerulonephritis concurrent with granulomatous interstitial nephritis due to disseminated histoplasmosis.