IgG₄-related tubulointerstitial nephritis associated with chronic lymphocytic leukemia

Background: Tubulointerstitial nephritis (TIN) is typically seen in association with drug exposure and infection or in autoimmune diseases such as Sjogren's syndrome or systemic lupus erythematosis. The recently described IgG₄-related systemic diseases can affect many organ systems including the kidney and typically respond to corticosteroid treatment. Case: We present a case of IgG₄-related TIN in a patient with concomitant chronic lymphocytic leukemia. To our knowledge, IgG₄-related TIN has not been associated with any hematological disorder such as chronic lymphocytic leukemia. Conclusion: We propose that all kidney biopsies with significant plasma cell infiltrate should be stained for IgG₄ as response to treatment is common.