Pulmonary Tumor Thrombotic Microangiopathy With Versican Expression in a Patient With Advanced Gastric Cancer: A Case Report of a Rare Autopsy.

Pulmonary tumor thrombotic microangiopathy (PTTM) is a rare but fatal complication of a malignant tumor that causes rapidly progressive pulmonary hypertension (PH). We report the case of a 70-year-old Japanese man who died of respiratory failure during chemotherapy for gastric cancer and was diagnosed with PTTM at autopsy. The autopsy revealed PTTM-specific histological findings, such as tumor emboli with fibrin-rich clots and fibrocellular intimal proliferation in the vessels. The cancer cells were immunohistochemically positive for vascular endothelial growth factor and platelet-derived growth factor, whereas the thickened intima of the pulmonary arteries was positive for versican (VCAN). As VCAN is an extracellular matrix proteoglycan that is dramatically increased in vascular lesions of pulmonary arterial hypertension, this case demonstrates that VCAN is also involved in the pathophysiology of PTTM.