We report the case of a young female patient who presented with chest pain, having a background of systemic complaints and a history of essential thrombocytosis. Transesophageal echocardiography (TEE) was suggestive of an intramural hematoma of the distal ascending aorta and transverse arch, confirming computed tomography findings. However, surgery revealed only diffuse aortic wall thickening without hematoma or dissection, despite an epiaortic ultrasonogram corroborating the TEE findings. Histopathology demonstrated inflammation involving all layers of the aortic wall, with intimal fibrosis, disrupted elastic fibers in the media, and marked fibrous thickening of the adventitia with multiple necrobiotic foci; the latter were apparently the cause of the markedly hypodense region mimicking intramural hematoma on imaging. The findings were consistent with Takayasu's arteritis, a large vessel vasculitis of unknown etiology that predominantly affects females.