Plasma Cell precursor and Other Disorders

A unique presentation of Light Chain Deposition Disease: kidney disease with no proteinuria

P-295: A unique presentation of Light Chain Deposition Disease: kidney disease with no proteinuria

Friday, September 27, 2024

Dipanjan Debnath, MD

Fellow, Hematology and Oncology
Allegheny Health Network Cancer Institute
Pittsburgh, Pennsylvania, United States

Introduction: Monoclonal gammopathy of renal significance (MGRS) is a group of disorders caused by a nonmalignant or premalignant B cell or plasma cell clone causing kidney injury through secretion of a monoclonal immunoglobulin. Patients with light chain deposition disease (LCDD) commonly present with acute, subacute or chronic kidney injury, and proteinuria, with or without hematuria. We present a unique case of LCDD with kidney injury but no proteinuria.

Methods: 64-year-old fit male with no comorbidities presented with slowly declining renal function over 2 years with GFR 39 mL/min/1.73 m2, elevated blood urea nitrogen 28 mg/dL and serum creatinine 1.89 mg/dL. Serum protein electrophoresis and immunofixation did not reveal a monoclonal spike. He had elevated kappa free light chains (FLC) 140 mg/dL, elevated lambda FLC 33.5 mg/dL with a high kappa/lambda FLC ratio 4.2. Given patient's elevated FLC ratio in the setting of worsening renal function, a bone marrow biopsy was performed that showed atypical plasma cells with Dutcher bodies that constituted 5-10% of the total cells but were polytypic with no light chain restriction. Cytogenetic studies and Florescent in-situ Hybridization revealed the presence of CCND1/IGH fusion gene involving 8.6% of the cells, resulting from an unbalanced translocation involving chromosomes 11 and 14, t(11:14). Skeletal survey and FDG PET scan did not show any evidence of lytic lesions. Given the inconclusive bone marrow biopsy, kidney biopsy was performed revealing kappa LCDD with linear staining of the renal basement membranes.

Results: A diagnosis of LCDD was thus made and the patient was started on treatment with daratumumab, cyclophosphamide, bortezomib and dexamethasone followed by daratumumab maintenance.

Conclusions: MGRS has been described by the International Kidney and Monoclonal Gammopathy Research Group (2012) as patients meeting criteria for monoclonal gammopathy of undetermined significance, with kidney injury being attributed to the underlying monoclonal protein. The kidney injury is primarily caused by the abnormal deposition or activity of monoclonal proteins in the kidney, including, light chains, heavy chains, or intact immunoglobulins, produced by small, nonmalignant or premalignant plasma cell or B cell clones. Patients with LCDD usually have abnormal FLC ratio, hematuria and proteinuria ≥1.5g/day. However, our patient with biopsy-proven LCDD presented with non-proteinuric kidney dysfunction, which has not been previously reported. Although LCDD is considered a nonmalignant or premalignant hematologic condition, patients with LCDD can develop progressive kidney disease and end-stage renal disease if not treated promptly. This case highlights the importance of having a high index of suspicion, in patients with monoclonal gammopathy and an unexplained decrease in renal function with or without proteinuria, to proceed with kidney biopsy, as improved renal outcomes have been associated with hematologic response from clone directed therapy.