**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.**
Morgane Thiry
Departments of Hematology, Cliniques universitaires Saint-Luc, UCL, 1200 Brussels, Belgium

**Main Body of the Abstract**
Amyloidosis is characterized by deposition of amyloid fibrils in various tissues and organs, with AL and ATTR being most common forms. Synovium is an uncommon site of extramedullary involvement in AL amyloidosis with only few cases reported so far. We described a case of synovial amyloidosis as the initial presentation of a multiple myeloma-associated AL amyloidosis.
A 73-year old male was referred for swelling, pain and stiffness of the left knee, with a gradual increase in complains over the past 12 months. MRI showed a large tumoral mass of 64x40 mm, with a diffuse synovial thickening of the knee and osteolytic lesions. CT-guided biopsy identified characteristic lambda light chains amyloid deposits. PET-scan showed an increased uptake in both knees, but also hips, shoulders and left ankle. Additional MRI confirmed a pathological synovial thickening at all sites. Investigations identified a lambda stage IA, ISS 2, standard-risk MM, as well as a bilateral carpal tunnel syndrome, cardiac and renal amyloid involvement. A VCD combination was initiated with a significant improvement in arthritis-related symptoms. VGPR was reached after 4 cycles, but cardiomarkers values remained unchanged. Treatment was shifted to DRd, for 12 cycles with complete hematological response and dramatic improvement of cardiomarkers. Four years after diagnosis, there are no sign of relapse.
Amyloid arthropathy as initial manifestation of MM is uncommon and can cause synovial thickening, subcutaneous nodules and erosive bone lesions, responsible for joint stiffness and arthralgia, mimicking rheumatoid arthritis. Therefore, differential diagnosis of chronic polyarthralgia should include systemic AL amyloidosis.



Arthropathy of the knees as initial manifestation of AL amyloidosis PA167 (#497)

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.