A Case of ANCA Negative Pauci-immune Crescentic Glomerulonephritis in Mixed Connective Tissue Disease

Pauci-immune crescentic glomerulonephritis (CrGN) is one of the most common causes of rapidly progressive glomerulonephritis. The majority of patients with pauciimmune CrGN have circulating antineutrophil cytoplasmic autoantibodies (ANCA). Approximately 10% of systemic vasculitides patients test negative for ANCA. Majority of the ANCA negative pauciimmune CrGN described in the literature have not shown associations with connective tissue diseases. Only isolated case reports of associations with systemic lupus erythematosus and scleroderma have been described. We report the case of a 24 yr lady who was diagnosed to have a pauciimmune crescentic glomerulonephritis on renal biopsy, and was found to be ANCA negative. Subsequently her collagen profile revealed a mixed connective tissue disease, even though she did not have any other systemic manifestations of the disease at presentation. We presume that antiendothelial antibodies (AECA) may have a role in the pathogenesis of the disease.