Cyclophosphamide-induced cardiotoxicity with a prolonged clinical course diagnosed on an endomyocardial biopsy.

A 31-year-old woman with primary mediastinal large B-cell lymphoma refractory to conventional chemotherapy was treated with high-dose chemotherapy containing cyclophosphamide (CY). Subsequently, she was treated with auto peripheral blood stem cell transplantation. Although a complete remission was obtained, heart failure developed two months later. Echocardiography showed an impaired systolic function with pericardial effusion. A biopsy of the endomyocardial region from the left ventricle demonstrated spotty myocardial hemorrhage and myocardial fibrosis with disruption and aggregation of mitochondrial cristae. Based on these findings, CY-induced cardiotoxicity was diagnosed. The patient was treated with conventional therapy for heart failure, which required approximately one year to improve her condition.