Acute Cor Pulmonale Caused by Pulmonary Tumor Thrombotic Microangiopathy as the Initial Presentation of Multiple Myeloma: A Case Report

Pulmonary tumor thrombotic microangiopathy (PTTM) is a rare cause of acute cor pulmonale, typically associated with advanced solid tumors; its occurrence as the initial presentation of multiple myeloma (MM) has not been described. A 45‐year‐old woman developed acute right heart failure on postoperative day 1 after uterine myomectomy. Echocardiography showed a pulmonary artery systolic pressure of 86 mmHg with a D ‐shaped left ventricle and right ventricular dysfunction (TAPSE 10 mm); CTPA excluded pulmonary embolism but revealed bilateral ground‐glass opacities. Platelet count fell from 115 × 10 9 /L preoperatively to 30 × 10 9 /L. An overlooked preoperative globulin of 67 g/L prompted serum protein electrophoresis and immunofixation, which identified an IgG κ M‐protein; bone marrow aspiration revealed 14% morphologically abnormal plasma cells. Presumed MM‐associated PTTM was treated with heparin and sildenafil. The platelet count recovered, and a follow‐up echocardiogram on day 7 showed normalized cardiac structure and function. The patient self‐discontinued rivaroxaban 1 week after discharge and died 3 months later from progression of untreated MM. In CTPA‐negative acute cor pulmonale with unexplained thrombocytopenia, an elevated globulin on routine biochemistry may be the only early clue to a plasma cell disorder, and timely anticoagulation with pulmonary vasodilation may buy time for definitive therapy.