AKI Secondary to Acute Interstitial Nephritis in a Patient with Adult T Cell Leukemia/Lymphoma

Introduction: Acute interstitial nephritis (AIN),characterized by interstitial inflammation and edema,rapidly deteriorates renal function.It is often underreported due to infrequent biopsies,empirical treatment preference,or clinical suspicion leading to withdrawal of the offending agent.Pathogenesis involves antigen-induced T helper cell and macrophage activation, cytokine release, and increased extracellular matrix production. We report a rare case of AIN associated with Adult T-cell Leukemia/Lymphoma (ATLL). Case Description: A 40-year-old female with a history of HTLV-1/3-positive T-cell lymphoma (Adult T-cell Leukemia/Lymphoma - ATLL), diagnosed via skin biopsy in January 2022, presented with declining renal function. Initial management included EPOCH chemotherapy and azathioprine, followed by a CRISPR trial involving flucytosine and chemotherapy conditioning. Pegylated interferon (IFN) therapy began in July 2024, and antiretroviral therapy with bictegravir, emtricitabine, and tenofovir alafenamide commenced in August 2024. Both therapies were discontinued in November 2024 due to significant facial swelling, which persisted despite cessation. Concurrently, renal function deteriorated from baseline creatinine (0.8-1.1 mg/dL) to 1.4 mg/dL on admission with peak at 7.9 mg/dL. Urine studies revealed a protein-to-creatinine ratio of 0.6 g and persistent pyuria (11-20 WBCs/hpf). Serologies were negative; peripheral eosinophilia was noted. Persistent renal impairment, ongoing pyuria, peripheral eosinophilia, and minimal proteinuria led to kidney biopsy. Findings confirmed AIN, likely secondary to underlying ATLL, given medication discontinuation since November 2024. Pathology showed T-cell gene rearrangement and malignant cells. The patient received high-dose IV methyl prednisone followed by a 6-week steroid taper and required hemodialysis from 12/12-12/30. Renal function recovered, hemodialysis ceased, and creatinine stabilized at 1.4-1.8 mg/dL. Discussion: AIN predominantly associates with drugs, infections, and systemic diseases; malignancy association is rare, with only one other reported ATLL-associated case. Persistent renal dysfunction and malignant biopsy cells suggest malignancy-related AIN in our case.Remarkably, despite delayed intervention, renal recovery was achieved, indicating potential therapeutic response despite prolonged disease progression