[Medial necrosis of the pulmonary artery in ruptured aneurysm].

Fifty years ago the first author of this paper described the entity known as idiopathic medial necrosis of the aorta. The present report describes two cases of ruptured aneurysm of the main pulmonary artery. The histologic alterations of the arterial wall were the same as in the much more common aneurysms of the aorta, viz. severe medial necrosis and mucoid degeneration. The findings are discussed and compared with 20 cases documented in the literature. Physical (hypertension) as well as biochemical factors appear to play an essential role in the pathogenesis of medial necrosis.