Direct communication between pulmonary artery and left atrium.

In this article an autopsy finding of a rare congenital anomoly is presented. We found only 28 cases in the literature. Four anatomic variations have been defined, and our case was of type II. The morphogenetic mechanism is a matter for discussion. The previous reports include inadequate pathological examinations. Our histologic findings support the arterial nature of the aneurysmal sac.