Abstract
Initial diagnosis: A 60-year-old male presented with initial diagnosis chest tightness, fatigue, and arrhythmia. Indications for plasma cell tumour: Initial imaging suggested amyloidosis due to myocardial thickening. Left ventricular hypertrophy and delayed enhancement on Magnetic Resonance Imaging (MRI), along with an elevated κ:λ ratio, raising suspicion for a plasma cell tumour. Confirmation of the plasma tumour: Further diagnostic tests, including immunofixation electrophoresis and myocardial biopsy, confirmed a plasma cell tumour. The patient was diagnosed with light chain (AL) amyloidosis, a subtype of plasma cell tumor, confirmed by bone marrow biopsy and immunohistochemistry. Treatment: Treatment with bortezomib, dexamethasone, and daratumumab resulted in significant symptomatic improvement. Conclusion: This case underscores the importance of considering plasma cell disorders in unexplained cardiac hypertrophy and highlights the need for early diagnostic strategies and targeted therapies.