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AL Amyloidosis Bone Marrow Biopsy Mandatory — ESENeph MCQ

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HardGlomerulonephritisAL Amyloidosis Bone Marrow Biopsy MandatoryESENeph

A 60-year-old man presents with ankle oedema, proteinuria (uPCR 480 mg/mmol), and eGFR 42 mL/min/1.73m2. Serum free light chain ratio is abnormal (kappa:lambda 0.08). Renal biopsy shows Congo red positive deposits in the mesangium and vessel walls with apple-green birefringence under polarised light. Immunohistochemistry confirms lambda light chain restriction. SAP scan shows renal and cardiac uptake. What is the most important additional investigation to determine treatment?

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Correct answer: C — Bone marrow biopsy with flow cytometry

AL amyloidosis with renal and cardiac involvement requires bone marrow biopsy to quantify the clonal plasma cell burden and guide treatment. The underlying clonal disorder (usually a plasma cell dyscrasia, occasionally lymphoplasmacytic lymphoma) determines the treatment approach — typically bortezomib-based chemotherapy (e.g., VCd: bortezomib, cyclophosphamide, dexamethasone) or daratumumab-based regimens for eligible patients. Cardiac staging (NT-proBNP and troponin — Mayo 2012 staging) is also critical as cardiac AL amyloid carries the worst prognosis and determines treatment intensity. The haematological response (free light chain reduction) predicts organ response.

Reference: Palladini et al 2020 – AL Amyloidosis Treatment; NICE NG228 – Systemic AL Amyloidosis