When rare meets routine: A case report of amyloid light-chain amyloidosis with multiorgan involvement in primary care

ABSTRACT

Systemic immunoglobulin amyloid light-chain (AL) amyloidosis is a rare, life-threatening disease characterised by extracellular deposition of insoluble amyloid fibrils, leading to progressive multiorgan dysfunction. Its diverse clinical manifestations frequently overlap with common primary care conditions, delaying diagnosis. We report the case of a 70-year old man with hypertension and coronary artery disease who presented to a primary care clinic with bilateral lower limb oedema and haematuria. By the 7th month, systemic AL amyloidosis was clinically suspected based on evolving multisystem findings. Serial investigations revealed unexplained significant proteinuria, concentric left ventricular hypertrophy, heart failure with preserved ejection fraction and poor tolerance to standard heart failure therapy. The new appearance of periorbital purpura and macroglossia, together with markedly elevated cardiac biomarkers and electrocardiographic–echocardiographic discordance, reflected features of restrictive cardiomyopathy, further raising suspicion for systemic AL amyloidosis. Renal biopsy demonstrated Congo red-positive amyloid with lambda light-chain restriction; bone marrow examination revealed clonal plasma cell proliferation; and serum free light-chain assay confirmed monoclonal lambda light chains, fulfilling the International Consensus Classification 2022 diagnostic criteria for systemic AL amyloidosis. Definitive diagnosis was established at the 9th month. The haematology team initiated anti-clonal therapy with bortezomib, cyclophosphamide and dexamethasone; the patient died of pneumonia 3 months later, after the third treatment cycle. This case highlights the diagnostic challenges of systemic AL amyloidosis in primary care and the importance of recognising clinical discordance, pathognomonic signs and evolving multisystem involvement. Early identification and timely multidisciplinary referral are critical to optimising outcomes in this rare but devastating disease.