A case report of segmental arterial mediolysis in which computed tomography angiography was useful for diagnosis

Abstract

A 48-year-old male presented to our hospital with abdominal pain. Laboratory studies showed no abnormality, the severity of his abdominal pain decreased, and the patient was discharged. Five days later, the patient visited a neighborhood clinic because of fever with a 3-day history of temperatures of approximately 38 °C. The patient was admitted to our hospital 6 days after his initial visit. Laboratory investigation revealed a C-reactive protein level of 18.2 mg/dL. Abdominal computed tomography (CT) showed an 80 × 60 mm hematoma behind the descending colon, but no extravasation was detected. Thin-slice maximum-intensity-projection images from CT angiography (CTA) showed irregular narrowing and intermittent fusiform dilatations of the left colonic artery, suggesting a vascular disease, such as segmental arterial mediolysis (SAM). Digital subtraction angiography showed local irregularity, and 'beading and narrowing' of the left colonic artery, similar to the findings on CTA. Left hemicolectomy was electively performed on the twenty-fifth hospital day. Histological findings were consistent with SAM. Thus, CTA was a useful modality for the early diagnosis of SAM.

Keywords: CT angiography (CTA); Digital subtraction angiography (DSA); Maximum-intensity-projection (MIP) images; Segmental arterial mediolysis.

Fig. 1

Axial computed tomography (CT) showing an 80 × 60 mm hematoma, surrounded by arrows in plain image (a), behind the descending colon. b The early phase of a contrast-enhanced study shows no stain or extravasation of contrast-enhanced medium. c Coronal contrast-enhanced CT shows the hematoma surrounded by arrows

Fig. 2

a Maximum-intensity-projection (MIP) image from contrast-enhanced coronal CT angiography. b Extended figure of part of the circulation in (a) demonstrates intermittent arterial dilatation like fusiform aneurysms (arrow) in the left colonic artery

Fig. 3

a Digital subtraction angiography of the inferior mesenteric artery in the arterial phase. b Extended figure of the distal portion of the left colonic artery in (a) shows fusiform dilatation and string-of-beads appearance (arrow). Extravasation was not detected

Fig. 4

Dorsal position (a) and left anterior oblique (b) of CT colonography. The descending colon became intermittently blocked by the hematoma (arrow)

Fig. 5

a Resected specimen revealed a 70 × 45 × 40 mm hematoma in the side of the serosa of the descending colon. b Cut surfaces of the serial section of the hematoma: the left colonic artery was distended and was present in the mid-portion of the hematoma (arrow)

Fig. 6

Histopathological examination of the resected left colonic artery. a Hematoxylin and eosin staining (×20) and b Elastica-Masson staining (×20) show that the wall of the artery is partially dissected with intramural hemorrhage. c Higher magnification (×400) of a square part of (a) shows vacuolar degeneration of smooth muscle cells in the tunica media (arrow). d Higher magnification (×200) of the square part of (b) shows irregular-shaped degeneration of the tunica media with focal fibrosis