Intravascular papillary endothelial hyperplasia in an aneurysm of the superficial temporal artery: Report of a case.

We herein report a rare case of an intravascular papillary endothelial hyperplasia in an aneurysm of the superficial temporal artery. The patient was a 67-year old Japanese woman. She noticed a throbbing swelling in her left forehead, which had gradually been increasing in size. She had no previous history of head trauma. Ultrasonography and three-dimensional computed tomographic angiography revealed an aneurysm with a mural thrombus measuring 10 mm in diameter fed by the frontal branch of the left superficial temporal artery. The aneurysm of the superficial temporal artery was dissected from the surrounding tissues, and was resected after ligation of feeding vessels. A microscopic examination revealed papillary endothelial hyperplasia in a true aneurysm. Nontraumatic aneurysms of the superficial temporal artery are rare. In the previous English literature, there have only been a few reports of papillary endothelial hyperplasia in an artery, and none in an aneurysm of the superficial temporal artery.