Characteristic tubulointerstitial nephritis in IgG4-related kidney disease

Abstract

IgG4-related kidney disease (IgG4-RKD), a progressive renal disorder, often leads to renal dysfunction. Tubulointerstitial nephritis (TIN) is the particular pathophysiology of IgG4-RKD responsible for progression and IgG4-related TIN is a distinct entity of IgG4-RKD. Renal biopsy is the gold standard for diagnosis in IgG4-related TIN, and a characteristic pattern of histology has been identified. A large IgG4 (+) plasma cell population, characteristic fibrotic pattern (storiform or “bird’s eye” fibrosis), and immune complex deposition within the tubulointerstitial compartment are the particular lesions associated with IgG4-related TIN. However, not every case of IgG4-RKD is associated with striking fibrosis, and some are difficult to distinguish from other renal processes that may have TIN. Because full details of the pathogenesis of IgG4-related TIN remain to be elucidated, the diagnosis does not yet have a molecular basis but rather is made through a synthesis of clinical, radiological and histological findings.