AL Amyloidosis Recognition — EECC MCQ

Correct answer: B — AL (light chain) amyloidosis — the abnormal free light chain ratio indicates a clonal plasma cell disorder producing amyloidogenic immunoglobulin light chains; urgent haematology referral is essential as AL amyloidosis has a much worse untreated prognosis than ATTR

AL (immunoglobulin light chain) amyloidosis results from clonal plasma cell proliferation producing misfolded light chains that deposit as amyloid in multiple organs. Cardiac involvement occurs in ~50-70% and is the leading cause of death. Key distinguishing features from ATTR: (1) abnormal serum free light chains and/or monoclonal protein on serum/urine immunofixation; (2) rapid progression (median survival ~6 months untreated with cardiac involvement); (3) multiple organ involvement (kidneys, liver, soft tissues, peripheral nerves); (4) macroglossia and periorbital purpura (pathognomonic if present). The 2023 ESC Cardiomyopathy Guidelines mandate that monoclonal protein studies MUST be performed in ALL patients with suspected cardiac amyloidosis BEFORE accepting a positive DPD/PYP scan as diagnostic of ATTR — AL amyloidosis can produce false-positive bone tracer uptake in ~20% of cases. AL amyloidosis treatment targets the underlying plasma cell clone (chemotherapy, autologous stem cell transplant).

Reference: ESC (2023): Cardiomyopathies Guidelines