Mycobacterium Avium Complex (MAC)-Induced Pauci-Immune Necrotizing Glomerulonephritis

Introduction: Rapidly progressive glomerulonephritis (RPGN) is a rare syndrome with rapid loss of renal function that has a high rate of renal failure. Histologically, there are numerous glomerular crescents. It is classified according to immune complex deposition. Pauci-immune represents up to 80% of RPGN cases and the incidence in the US is around 7-10 cases per 1 million people per year. ANCAs are negative in approximately 10-30% of patients with pauci-immune necrotizing glomerulonephritis (PING). Case Description: A 64-year-old male with COPD, OSA, CAD presented with a recent MAC diagnosis awaiting susceptibility. He was doing well until he started having pleuritic chest pain, dyspnea, foamy white sputum, fatigue, nausea, swelling of the lower extremities, and dark urine with reduced urine output. Labs were significant for creatinine of 9.42 from 0.78 a month earlier, BUN 101 from 12, negative ANCA, serology and blood cultures. Active UA. Negative renal ultrasound. PET/CT showed new cavitated lesions within the lungs, diffuse pleural thickening and nodular hypermetabolic activity demonstrated within the left hemithorax, hyperdense material within the right lobe of liver. Echo showed LV thrombus with no vegetations. A kidney biopsy showed severe crescentic GN with ATN and negative IF representing pauci-immune GN. A multidisciplinary team was formed including nephrology, infectious disease and ICU team to discuss this challenging case with recent MAC diagnosis and how to treat in the need of immunosuppression. The patient was started on hemodialysis and the decision was not to start immunosuppression. Discussion: PING has no deposits or very scant deposits of IgM, IgG or C3 on IF. To our knowledge, our case is the first to link MAC with ANCA negative PING. In a recent unique case series, 9 patient was diagnosed with PING associated with an acute bacterial infection [Staph.A (4), E.coli (1), Klebsiella pneumoniae (1), Strep. parasanguinis (1), and Staph. Epi.(1)]. Bacterial infection-associated PING has no endocapillary proliferation or intense C3 glomerular deposition in contrast to postinfectious glomerulonephritis. Differentiating between infection-associated and other forms of PING is crucial in the management, as the use of immunosuppressive drugs without associated specific treatments may have negative consequences.