[A rare case of severe pulmonary artery hypertension. Thrombosing pulmonary microangiopathy due to tumor].

We report a case of acute respiratory insufficiency with acute cor pulmonale and a fatal outcome. Right cardiac catheterisation enabled a diagnosis of precapillary pulmonary arterial hypertension to be made with a mean pulmonary arterial pressure of 61 mmHg and a pulmonary capillary pressure of 12 mHg. An autopsy was carried out and this revealed a microscopic pulmonary tumour emboli with lymphangitis carcinomatosis. In particular, it showed an association of fibrocellular proliferation at the level of the intima in the small calibre pulmonary arteries and arterioles permitting the unusual diagnosis of thrombosing pulmonary microangiomathy due to tumour. The physiopathological mechanism of this particular form of pulmonary tumour emboli is discussed; it would be secondary to an activation of the coagulation systems by the embolic tumour cells. Once activated, it is the lesions in the intima and not the carcinoma cells which generate the pulmonary arterial hypertension by vascular obstruction.