Segmental Arterial Mediolysis in the Superficial Temporal Artery of a Young Patient: A Case Report.

Segmental arterial mediolysis (SAM) is a rare arterial degenerative disease that starts with degeneration of the smooth muscle layer, leading to aneurysm formation. SAM commonly occurs in the colonic arteries and other abdominal, vertebral, internal carotid, coronary, and pulmonary arteries. Early detection is crucial because of the risk of intra-abdominal or subarachnoid hemorrhage. This report presents the case of a 15-year-old male who presented with a 6-month history of left-sided preauricular pain and a subcutaneous nodule. Ultrasonography revealed a superficial temporal artery aneurysm. Computed tomography angiography showed aneurysmal dilation, which led to excision. Histopathological examination confirmed SAM with medial smooth muscle cell disruption and vacuolar degeneration. Systemic vascular screening revealed no other abnormalities. Reports of SAM occurring in the superficial vessels of young patients are rare. This case highlights the importance of considering SAM in young patients with aneurysms and the need for comprehensive vascular evaluation.