Significance of Crescentic Glomeruli in Acute Kidney Injury with Rheumatoid Arthritis.

Crescentic glomerulonephritis (GN) without immune reactants or deposits (referred to as pauci-immune) is typically characterized by the presence of anti-neutrophilic cytoplasmic antibodies (ANCA). While ANCA-negative patients might be expected to have a more benign course, they often have poor renal outcomes, especially without treatment with steroids and immune-modulating therapy. Pauci-immune crescentic GN can also co-exist with other autoimmune conditions, including rheumatoid arthritis (RA). Here, we describe an ANCA-negative patient with RA who developed dialysis-requiring acute kidney injury (AKI) with findings consistent with focal pauci-immune crescentic GN (i.e., no IgG or immune complex on kidney biopsy). Coexistent conditions included Klebsiella sepsis attributed to pneumonia, rhabdomyolysis, leukocytoclastic immune-mediated skin vasculitis, and positive ANA. He had spontaneous improvement in renal function without immunosuppressive therapy. This crescentic GN was not associated with poor renal outcome as AKI resolved with supportive care and treatment of his infection. The AKI was likely multifactorial with co-existing acute tubular necrosis in the setting of Kebsiella sepsis and rhabdomyolysis, and the crescentic GN was felt more likely to be related to the infection rather than having a primary role. This case highlights the importance of viewing crescentic GN in the context of the clinical picture, as it may not always lead to the need of aggressive immune suppression and is not a universally poor prognostic kidney finding. However, these cases do warrant close follow-up as our patient had recurrent RA disease manifestations over the next 2 years that eventually led to his death from severe pulmonary hypertension.