E BUTLER1, D LEE1,4, S GIBBS2, 3, 4
1Department of Renal Medicine, Eastern Health, Victoria; 2The Victorian and Tasmanian Amyloidosis Service; 3Department of Haematology, Eastern Health, Victoria; 4Eastern Health Clinical School, Monash University, Melbourne.
Aim: To identify cases of renal amyloidosis incorrectly subtyped as light chain amyloidosis (AL) and highlight patient and disease characteristics to avoid incorrect management.
Background: Amyloidosis involves the deposition of misfolded protein fibrils in multiple organs. AL is the most common in chronic kidney disease (CKD) but subtype diagnosis is essential for prognosis and treatment.
Methods: We reviewed the Victorian and Tasmanian Amyloidosis Service (VTAS) database for cases and clinical characteristics of renal AL and non-AL.
Results: The VTAS database identified 137 patients, 38 with renal amyloidosis: 31 AL-type (82%), 2 Leukocyte Chemotactic Factor 2 (LECT2) (5%), 1 Fibrinogen a-α chain (3%), and 4 AA (10%). 2 patients with LECT2 were Egyptian, had isolated renal involvement with non-nephrotic-range proteinuria and were diagnosed using mass spectrometry and LECT2 immunohistochemistry. One progressed to end stage kidney disease (ESKD); the other has stable Stage IIIB CKD. Fibrinogen a-α chain is a nephrotic, hereditary condition where amyloid deposits are characteristically restricted within expanded glomeruli, as with our patient. Diagnosis was established using mass spectrometry and genetic testing. AA, secondary to infection/inflammatory states, was identified in 4 patients with nephrotic-range proteinuria diagnosed on immunohistochemistry. The cases of AA included Familial Mediterranean Fever (FMF) treated with colchicine (stable renal function); a rare and lethal autoimmune inflammatory skin condition; untreated metastatic Carotid Body Paraganglioma progressed to ESKD; and unknown aetiology with progressive CKD.
Conclusion: Almost 20% of patients with renal amyloidosis don’t have AL. Ethnicity, isolated renal involvement and histological findings should prompt investigation of non-AL, as chemotherapy, with associated toxicities, has no therapeutic role. Patients may benefit from an Australian Amyloidosis Network centre to confirm the subtype and access novel treatments.