Pulmonary tumor thrombotic microangiopathy in an unknown primary cancer.

Pulmonary tumor thrombotic microangiopathy (PTTM) is a highly fatal complication of cancer leading to acute cor pulmonale and pulmonary hypertension. We present a case of 47-year-old male patient who developed acute breathlessness and died suddenly. The pulmonary vessels at autopsy on histopathologic examination showed the presence of fibrocellular intimal proliferation, fibrin thrombi and few tumor emboli consisting of malignant adenocarcinoma cells. There was associated lymphangiosis carcinomatosis. No primary visceral tumor was found despite extensive search. The patient had died following acute cor pulmonale with sudden pulmonary hypertension due to PTTM. This entity (PTTM) must be kept as a differential diagnosis in patients presenting with acute breathlessness especially in cases of cancers.