Histopathologic Characteristics of a Coronary-pulmonary Artery Fistula with a Coronary Artery Aneurysm.

Here, we report a case of a 59-year-old woman with a coronary-pulmonary artery fistula with a concomitant coronary artery aneurysm, which comprised an anomalous coronary artery originating at the right coronary cusp, an aberrant branch of the left anterior descending artery, and a coronary artery aneurysm draining into the main pulmonary artery. Histopathologically, non-dilated anomalous coronary artery showed the preservation of internal elastic lamina and medial smooth muscle cell phenotype which lacked in the aneurysmal wall. Thus, the disrupted internal elastic lamina and phenotypic change of medial smooth muscle cells might contribute to aneurysm formation in a coronary-pulmonary arterial fistula.