A giant thrombus in the right atrium of a patient with acute promyelocytic leukemia M3.

Acute promyelocytic leukemia is a special type of acute myeloid leukemia. Patients with this disease are at high risk of complications. Right atrial thrombosis is a rare but potentially serious complication. A 55-month-old girl with acute promyelocytic leukemia M3 was in her last phase of treatment. Radiologic examination revealed an echo structure in the right atrium that was still present after 6 weeks of anticoagulation treatment with enoxaparin. Cardiac surgery was performed to remove the mass, which was found to be a calcified thrombus. Although this is a rare occurrence, recognition of the possibility of a calcified thrombus may minimize misdiagnosis and allow surgical retrieval if the thrombus is sufficiently large.