Cardiac light chain amyloidosis secondary to Waldenström's macroglobulinemia: A case report and review.

Cardiac light chain amyloidosis (AL) secondary to Waldenström's macroglobulinemia (WM) presents a complex challenge in medical practice due to its rarity and diagnostic difficulty. A 67-year-old male presented with symptoms of heart failure and was diagnosed with cardiac AL amyloidosis secondary to WM. The diagnosis of WM was confirmed through a combination of immunoglobulin (Ig) profile with abnormal IgM levels, bone marrow morphology, immunofixation electrophoresis, serum protein electrophoresis and gene mutation analysis. Cardiac amyloidosis was identified through cardiac echocardiography and confirmed through positive Congo red staining of bone marrow and apple green color transformation of an abdominal fat biopsy. The amyloid protein mass spectrometry indicated that the type of cardiac involvement was AL amyloidosis. The patient responded positively to the BR and BRD chemotherapy regimens but only showed a partial response (PR). In conclusion, a patient with WM-AL amyloidosis was diagnosed based on the presence of abnormal IgM paraprotein levels and the high Igλ C2 peak in the amyloid protein mass spectrometry. The BR (0.15 g bendamustine on days 2-3, 0.6 g rituximab on day 1) and BRD (2 mg bortezomib once a week for 4 weeks, 0.5 g rituximab on day 1 and 10 mg dexamethasone once a week for 4 weeks) chemotherapy regimens only achieved a partial response due to the existing irreversible organ impairment of the heart with chronic heart failure. The diagnosis of WM combined with cardiac AL amyloidosis is a challenge, and thus, it is necessary to improve clinical vigilance and early detection. Therapeutic strategies tailored to the individual patient's clinical profile are essential for optimizing outcomes, given the limited consolidated treatment evidence available for this rare condition.