A Case of Pulmonary Tumor Thrombotic Microangiopathy Caused by Adenocarcinoma of Unknown Primary Site

A previously healthy 59-year-old man presented with a 2-month history of exertional dyspnea and dry cough. He had been admitted to a nearby hospital because of advanced dyspnea. Echocardiography indicated pulmonary hypertension, and perfusion images showed multiple subsegmental defects. The patient was diagnosed with a pulmonary embolism, and anticoagulation therapy was initiated. However, the symptoms worsened, and he was referred to our hospital with shock and respiratory failure. Right heart catheterization demonstrated mean pulmonary arterial pressure (mPAP) of 58mmHg and cardiac index (CI) of 1.8L/min/m2. Percutaneous cardiopulmonary support (PCPS) was urgently performed to sustain the general circulation. Pulmonary tumor thrombotic microangiopathy (PTTM) was suspected; however, serum tumor marker levels, and contrast-enhanced computed tomography and esophagogastroduodenoscopy findings did not indicate the presence of any carcinoma. Severe pulmonary hypertension was treated with combination of epoprostenol, bosentan, and tadalafil. On hospital day 6, he was successfully removed from PCPS. Additionally, mPAP was 33mmHg and CI was 3.4L/min/m2. However, despite intensive care, he died of progressive respiratory failure. Just before his death, adenocarcinoma cells were found on both pleural and peritoneal cytology, but the primary lesion of the cancer could not be identified. Although PTTM is characterized by the intimal proliferation of pulmonary arterioles in patients with metastatic carcinoma, in the present case, specific vasodilation therapy was effective in improving hemodynamics.