#3922 CLINICOPATHOLOGICAL CHARACTERISTICS OF LIGHT AND HEAVY CHAIN DEPOSITION DISEASE: A CASE SERIES FROM A SINGLE CENTER

Abstract Background and Aims Light and heavy chain deposition disease (LHCDD) is the rarest form of monoclonal immunoglobulin deposition disease (MIDD) characterized by the deposition of the monoclonal light chain and heavy chain. At present, the large-scale clinical research data of LHCDD is limited. We explore the clinical-pathologic characteristics and outcome of LHCDD in a single center of China, to obtain a better understanding of this disease. Method We reviewed 65291 native kidney biopsies from January 2008 to December 2022. Ten patients with biopsy-proven LHCDD diagnosed were studies retrospectively. Results 4 males and 6 females, with an average age of 52.5 ± 8.9 years were enrolled. The patients were presented with hypertension (80%), anemia (90%), elevated serum creatinine (70%), proteinuria (100%), nephrotic syndrome (30%) and microscopic hematuria (90%). Serum immunofixation electrophoresis showed that 8 (80%) patients were positive for monoclonal immunoglobulin (IgG-κ/IgG-λ/IgA-λ: 3/2/3). Serum free light chain (FLC) ratio was abnormal in 9 (90%) patients. Among them, 5 patients had an Elevated FLC ratio (κ:λ > 1.65), and an FLC ratio < 0.26 was observed in 4 patients. Two patients were diagnosed with multiple myeloma. Histologically, nodular mesangial sclerosis was identified in 9 (90%) patients. Immunofluorescence showed that 6 patientshad depositions of heavy chain IgG (γ1-κ/γ1-λ/γ2-κ/γ2-λ/γ3-κ:2/1/1/1/1), and 4 patients of heavy chain IgA (α-κ/α-λ:1/3). During a median of 28 months of follow-up (range, 6–104 months) in 9 patients, 8 patients received chemotherapy. Three (33%) patients had complete hematologic remission (CR), 2 (22%) had very good partial hematologic response (VGPR) or partial hematologic response (PR), and 4 (44%) had no response (NR). One (11%) had stable/improved renal function, 6 (67%) had worsening renal function, and 3 (33%) progressed to ESRD. All 9 patients survived. Conclusion In this case series of LHCDD in a single center in China, light and heavy chain deposition in renal tissues was most frequent with IgG-κ, followed by IgA-λ, IgG-λ and IgA-κ. More than half patients had hematologic response but poor renal prognosis.