Abstract: FR-PO0468
Granulomatous Tubulointerstitial Nephritis (TIN) and Hypercalcemia Revealing Monoclonal B-Cell Lymphocytosis Progressing to Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma
Session Information
- AKI: Case Reports - TMA, Vasculitis, Immune-Mediated Injury, and Systemic Disease
October 23, 2026 | Location: Exhibit Hall A, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Acute Kidney Injury
- 102 AKI: Clinical, Outcomes, and Trials
Authors
- Cooper, Michael A., Maine Medical Center, Portland, Maine, United States
- AlShanableh, Zain, Maine Medical Center, Portland, Maine, United States
Introduction
Renal involvement in B-cell lymphoproliferative disorders may include direct infiltration or immune-mediated injury. Monoclonal B-cell lymphocytosis (MBL) is a benign precursor to chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL). This case demonstrates AKI secondary to granulomatous TIN in association with MBL-associated CLL/SLL.
Case Description
64-year-old woman with type 2 diabetes presented with vomiting, dry mouth/eyes, and AKI. Vitals and physical exam were unremarkable. Labs: WBC 4.5 thou/uL, Hg 13.6 g/dL, creatinine 3.2 mg/dL (baseline 0.8), BUN 43 mg/dL, Ca 9.9 mg/dL. Urinalysis revealed sterile pyuria. UPCR 0.41 g/g. Elevated anti-SSA led to the diagnosis of Sjögren’s syndrome. ANA, anti-SSB, ANCA, hepatitis B/C, HIV, SPEP/IFE, FLCs & complements were unremarkable. Flow cytometry showed monoclonal CD5+ MBL, CLL-type with low total cell count. Kidney biopsy revealed granulomatous TIN with CD5+ B-cell infiltration. Renal dysfunction was thought to be unrelated to MBL per oncology evaluation & hence attributed to Sjogren’s syndrome. Prednisone was initiated with initial resolution of AKI; however, worsened during taper, prompting rituximab initiation.
2-year course was complicated by severe hypercalcemia at 14 mg/dL with low PTH. PTHrP, SPEP/IFE and 1,25-dihydroxyvitamin D were unrevealing. Explorative lymph node biopsy confirmed CD5+ CLL/SLL & non-caseating granulomas raising concern for sarcoidosis. Patient did not meet criteria for CLL/SLL treatment and was initiated on TNF inhibitor for sarcoidosis.
Discussion
Granulomatous TIN is a subtype of TIN and common etiologies include infections, drugs, and systemic diseases like sarcoidosis, TINU, lymphomas and rarely Sjogren’s syndrome. MBL is defined by the presence of a clonal B-cell population in the peripheral blood without other features of CLL/SLL. It is classified into low and high-count subtypes based on clonal B-cell burden, with high-count MBL carrying a higher risk of progression to CLL.
This case underscores a few key teaching points: (1) MBL warrants ongoing monitoring given potential for progression, (2) unexplained hypercalcemia should prompt evaluation of malignancy including explorative lymph node biopsy, and (3) underlying cause of granulomatous TIN is difficult to pinpoint in patients with multiple etiologies and often requires trial of different treatment regimens.