IgG4-related Renal Disease Case Report and Review of Literature

ABSTRACT IgG4-related disease (IgG4-RD) is a clinical entity that involves multiple organs and is characterized by high levels of serum IgG4. We present a case of an elderly male reporting fatigue and weight loss, who after extensive workup, was diagnosed as a case of IgG4-related renal disease on kidney biopsy. A 73-year-old male patient, a reformed smoker with a history of acute coronary syndrome and bronchial asthma, presented with fatigue and weight loss for 6 months. Clinical examination was unremarkable. Investigations revealed mild anemia, azotemia, hyperglobulinemia, bland urinary sediment, insignificant proteinuria, and symmetrically enlarged kidneys. A kidney biopsy was performed, which demonstrated features of IgG4-related tubulointerstitial nephritis (TIN). Simultaneous serological investigations revealed a Kappa/Lambda ratio of 2.12, IgG–3110 mg/dL, and IgG4–3.56 g/L. The patient was treated with oral prednisolone for 6 months. IgG4-related disease is a multisystem immune fibro-inflammatory disorder of the elderly with a male preponderance, which involves all organs except the synovium. IgG4-related TIN presents with an insidious rise of creatinine, elevated IgG4 levels, peripheral eosinophilia in 40% of individuals, anti-nuclear antibodies (ANA) positive status in many, and hypocomplementemia. It is characterized by lymphoplasmacytic infiltration with IgG4+ plasma cells with IgG4/IgG ratio >40%, eosinophilic infiltrate, storiform fibrosis, and immune complexes in the tubular basement membrane. The mainstay of treatment is oral corticosteroids, with relapse noted in the majority, followed by a chronic indolent course. IgG4-related diseases are an emerging entity and have only been recently recognized. Awareness of the disease and a high index of suspicion is essential for early diagnosis to avoid irreversible organ damage.