Acute Kidney Injury Due to Granulomatous Interstitial Nephritis as the Initial Presentation of CLL/SLL Treated with Acalabrutinib.

Acute kidney injury (AKI) caused by granulomatous interstitial nephritis (GIN) accompanied by chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) is extremely rare. A 71-year-old man with severe AKI was diagnosed with CLL/SLL based on bone marrow and lymph node biopsy results. A renal biopsy revealed dense cortical infiltration of CLL/SLL cells and severe interstitial inflammation with granuloma formation, consistent with GIN. Acalabrutinib-Obinutuzumab combination therapy was effective for CLL/SLL, but prednisolone was required to achieve a renal function improvement. A renal biopsy is essential for the diagnosis, and corticosteroids play a key role in managing GIN-associated renal injury, even in the era of targeted therapies.