Congo red-positive cardiac kappa-AL amyloidosis in plasmacytoma -- case report and review of the literature.

We report on a 51-year-old female patient who was diagnosed in 2001 as suffering from plasmacytoma. The patient had had complaints of bilateral carpal tunnel syndrome in 1999, treated by a simple dissection without performing histological examination. Congestive heart failure had gradually developed since that time. In 2001 echocardiography revealed a pronounced thickening of the left ventricular wall with systolic and diastolic dysfunction. A kappa-light chain M component and kappa-light chain-restricted bone marrow plasmacytosis were detected. Amyloid deposits staining positive in the kappa-light chain-restriction analysis were observed in a gastric biopsy. Taking into consideration all these findings, a plasmacytoma-associated systemic AL amyloidosis was diagnosed. Cyclophosphamide/prednisolone chemotherapy regimen led to complete haematological remission. Cardiac transplantation, combined with autologous peripheral blood stem cell graft, was considered as the next therapeutic step, but the patient died while on the waiting list for transplantation. Autopsy detected a highly hypertrophic myocardium with narrowed heart cavities. Microscopic examination revealed dense, pink, acellular, Congo red-staining and kappa-immunoperoxidase-positive AL amyloid masses splitting the cardiomyocytes. The present case is remarkable as it demonstrates that carpal tunnel syndrome and congestive heart failure could be symptoms of plasma cell dyscrasia-associated amyloidoses.