Author Listing - Lead/ Submitting Author (we will be communicating with this individual): Name, Institution, City and State where the work was done. Co-authors will be added in a separate section.
Jinghua Wang, Department of Hematology, Guangdong Provincial People’s Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, Guangdong, China

Main Body of the Abstract
Background: Light chain deposition disease (LCDD) is a systemic disease characterized by abnormal production of monoclonal immunoglobulin light chains (LCs) deposited in multiple organs. The kidney is the principal involved organ, and the examination of renal biopsy specimens using immunofluorescence (IF) or immunoelectron microscopy (IEM) has proven to be a practical and sensitive method for the diagnosis of LCDD. We report here two clinical cases of LCDD, which exhibited identical electron microscope characteristics in the kidneys and labial salivary glands (LSG).
Case Report: Patient 1 was a 71-year-old woman presented with both lower extremities edema. Laboratory investigations showed decreased hemoglobin level of 80 g/L, increased 24-hr urinary protein level of 2102 mg. NT-proBNP and hs-cTnT levels increased to 630.3 pg/mL and 25.9 pg/mL, respectively; interventricular septum (IVS) thickness increased to 13.8mm on echocardiography. Immunofixation electrophoresis (IFE) of serum and urine were both positive for monoclonal λ LC. Serum free λ LC was elevated at 2308.08mg/L with κ/λ ratio of 0.01. Bone marrow examination showed 4% plasma cells with λ LC restriction. We then performed LSG biopsy for this patient suspected of amyloidosis. Electron-dense, granular, nonfibrillar, amorphous deposits along acinar basement membrane and capillary basement membrane were seen under IEM, and fine-grained substances aggregation were seen in some acinar cavities. The λ chain was positive but κ chain was negative for deposits. Further renal biopsy was performed and IEM confirmed electron dense deposits in the mesangial area, along the glomerular basement membrane (GBM) and tubular basement membrane (TBM), with λ chain-restricted staining. Patient 2 was a 54-year-old woman presented with chest distress and lower extremities edema. Laboratory results revealed very high level of 24-hr urinary protein (7310 mg), and raised NT-proBNP (765.5 pg/mL) and hs-cTnT (28.2 pg/mL) levels. Echocardiography showed thickened IVS of 13mm. IFE of serum and urine both revealed monoclonal IgG-κ. Serum free LC results were κ 2717.00 mg/L and κ/λ 186.86. Bone marrow examination revealed 6% monoclonal plasma cell infiltration. IEM examination of LSG showed electron dense deposits along capillary basement membrane, among focal interstitium, with κ chain-restricted staining. Further workup of renal biopsy demonstrated only κ chain staining in mesangial area, GBM and TBM by IF, and electron dense deposits by electron microscopy. Congo red staining for the biopsies of the two patients were all negative. Both of them were diagnosed with LCDD involving the kidneys, heart and soft tissue.
Summary & Conclusion: Evidences of monoclonal plasma cell and organ damage initially directed the patients to AL amyloidosis, which requires biopsy for confirmation. Surprisingly, we detected the characteristics of LCDD in LSG biopsy specimens, which were consistent with that in renal biopsies. The two cases demonstrate that LSG biopsy may be a quite simple and safe technique in the diagnosis of unsuspected LCDD, used as alternative to the biopsy of the organs involved.

**Author Listing - Lead/ Submitting Author (we will be communicating with this individual): Name, Institution, City and State where the work was done. Co-authors will be added in a separate section.**
Jinghua Wang, Department of Hematology, Guangdong Provincial People’s Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, Guangdong, China

**Main Body of the Abstract**
**Background:** Light chain deposition disease (LCDD) is a systemic disease characterized by abnormal production of monoclonal immunoglobulin light chains (LCs) deposited in multiple organs. The kidney is the principal involved organ, and the examination of renal biopsy specimens using immunofluorescence (IF) or immunoelectron microscopy (IEM) has proven to be a practical and sensitive method for the diagnosis of LCDD. We report here two clinical cases of LCDD, which exhibited identical electron microscope characteristics in the kidneys and labial salivary glands (LSG).
**Case Report:** Patient 1 was a 71-year-old woman presented with both lower extremities edema. Laboratory investigations showed decreased hemoglobin level of 80 g/L, increased 24-hr urinary protein level of 2102 mg. NT-proBNP and hs-cTnT levels increased to 630.3 pg/mL and 25.9 pg/mL, respectively; interventricular septum (IVS) thickness increased to 13.8mm on echocardiography. Immunofixation electrophoresis (IFE) of serum and urine were both positive for monoclonal λ LC. Serum free λ LC was elevated at 2308.08mg/L with κ/λ ratio of 0.01. Bone marrow examination showed 4% plasma cells with λ LC restriction. We then performed LSG biopsy for this patient suspected of amyloidosis. Electron-dense, granular, nonfibrillar, amorphous deposits along acinar basement membrane and capillary basement membrane were seen under IEM, and fine-grained substances aggregation were seen in some acinar cavities. The λ chain was positive but κ chain was negative for deposits. Further renal biopsy was performed and IEM confirmed electron dense deposits in the mesangial area, along the glomerular basement membrane (GBM) and tubular basement membrane (TBM), with λ chain-restricted staining. Patient 2 was a 54-year-old woman presented with chest distress and lower extremities edema. Laboratory results revealed very high level of 24-hr urinary protein (7310 mg), and raised NT-proBNP (765.5 pg/mL) and hs-cTnT (28.2 pg/mL) levels. Echocardiography showed thickened IVS of 13mm. IFE of serum and urine both revealed monoclonal IgG-κ. Serum free LC results were κ 2717.00 mg/L and κ/λ 186.86. Bone marrow examination revealed 6% monoclonal plasma cell infiltration. IEM examination of LSG showed electron dense deposits along capillary basement membrane, among focal interstitium, with κ chain-restricted staining. Further workup of renal biopsy demonstrated only κ chain staining in mesangial area, GBM and TBM by IF, and electron dense deposits by electron microscopy. Congo red staining for the biopsies of the two patients were all negative. Both of them were diagnosed with LCDD involving the kidneys, heart and soft tissue.
**Summary & Conclusion:** Evidences of monoclonal plasma cell and organ damage initially directed the patients to AL amyloidosis, which requires biopsy for confirmation. Surprisingly, we detected the characteristics of LCDD in LSG biopsy specimens, which were consistent with that in renal biopsies. The two cases demonstrate that LSG biopsy may be a quite simple and safe technique in the diagnosis of unsuspected LCDD, used as alternative to the biopsy of the organs involved.

Unsuspected light chain deposition disease diagnosed by labial salivary gland biopsy PC9 (#47)

We invite you to attend the XIX International Symposium on Amyloidosis to be held in Rochester, MN.

This symposium is organized as a hybrid meeting (with the focus on in-person) held from Sunday, May 26 through Thursday, May 30, 2024.

Together with the ISA Board and members of Mayo Clinic, a very attractive scientific hybrid program is being planned. The program will cover a variety of types of systemic amyloidosis: ATTR (hereditary and wild-type), AL (light-chain), AA and less frequent forms. There will be key lectures, specific symposia including those company sponsored, oral presentations and poster sessions of accepted abstracts.

COURSE DESCRIPTION
This program will provide a comprehensive review of state-of-the-art education in systemic amyloidosis: basic science, pathophysiology, diagnosis, current and emerging treatments. Scientific presentations will include competitive oral and poster abstracts. The rapid evolution of scientific discovery and expanding treatment options has created tremendous interest in the field and this meeting will fill and important gap in educating scientists and clinicians.