IgG4 Tubulointerstitial Nephritis- A Rare Autoimmune Presentation

IgG4 related disease is a recently recognized systemic disease involving multiple organs, including the pancreas, salivary glands, kidneys, lymph nodes, and retroperitoneum. It is characterized by dense infiltration of organs with lymphoplasmacytic cells that leads to fibrosclerosis and elevation in serum IgG4 levels. We present an 80-year-old Caucasian male with past medical history of DM2, coronary artery disease, hyperlipidemia, hypertension, and cerebral vascular accident with repeated episodes of acute renal failure (AKI). It initially was presumed as due to volume changes, however, that was ruled out with normal blood pressure readings of 119/73 mmHg. The patients Glomerular Filtration Rate (GFR) ranged from 16 to 24, BUN 33, and Creatinine 2.7 despite treatment with volume resuscitation, discontinuing ACE-inhibitors, and avoidance of NSAIDs. Renal ultrasound studies were negative for obstruction, and urine analysis negative for proteinuria. As time progressed his blood pressure continued to rise in value of 130/67 mmHg, while GFR remained below 25. On renal biopsy the pathology report illustrated chronic tubulointerstitial nephritis with mild mesangial immune complex deposition, a finding that correlates with IgG4-related disease. Congo red stain of the pathology specimen was negative for amyloid deposition, another causal factor for tubulonephritis. Improvement with fatigue and appetite was noted upon starting steroid treatment. Additionally, the GFR improved to an impressive value of 53 with 3 months of treatment.