Spontaneous rupture of the pulmonary artery.

A 45-year-old man presented with the sudden onset of diaphoresis, generalized weakness, and bilaterally achy arms. Physical examination revealed cyanosis of the head, neck, and upper chest with dyspnea and hypotension. He had distant heart sounds. An upright portable chest radiograph suggested widening of the mediastinum. A right arm venogram was consistent with extrinsic obstruction of the superior vena cava. A computed axial tomography scan demonstrated blood in the pericardium and indistinct widening of the pulmonary outflow tract. Autopsy revealed three tears of the pulmonary artery above the level of valve cusps, and thinning of the artery walls suggested cystic medial necrosis. These findings are suggestive of an acute spontaneous rupture of the pulmonary artery, possibly secondary to cystic medial necrosis.