Fig. 3

Histopathologic findings of resected specimen. a CT angiograph of the SMA on Day 6 indicating the origin of each section; letters A through I correspond to Fig. 3a through i (black lines). Red line indicates the position of the SMA resection stump. b Low-power view (LPV) (×100) with Elastica van Gieson (EVG) staining of the SMA adjacent to the proximal resection stump. Internal (white arrow) and external (black arrow) elastic laminae as well as arterial media have partially disappeared and there is prominent intimal proliferation (asterisk). On CT angiography, this region showed only mild vasodilatation but an entry point of latent dissection was seen. “P” indicates pseudolumen filled mainly with fibrin. c High-power view (HPV) (×400) with hematoxylin and eosin (HE) staining shows vacuolization (black arrow) and marked decrease in the number of vascular smooth muscle cells (SMCs). d LPV (×100) with EVG staining of the area slightly distal to the lesion shows latent dissection with preserved internal elastic lamina and eccentric intimal proliferation. e HPV (×400) with HE staining also shows a vacuolization-rich area (ellipse) in the arterial media and disturbed arrangement of medial SMCs. f LPV (×100) of the SMA with EVG staining of the area adjacent to the pseudoaneurysm neck (N) showing remarkable stenosis of the true lumen (T) due to intimal proliferation (asterisks). A small dissection (D) is also observed, but wall rupture and resultant aneurysm formation are predominant. Arterial wall adjacent to aneurysm neck lacks medial SMCs. g HPV (×400) with EVG staining of the SMA adjacent to the neck of the pseudoaneurysm. Arterial media between internal (I) and external (E) elastic laminae shows focal vacuolization (black arrows) and degeneration of vascular SMCs (white arrow). h LPV (×100) with EVG staining of the SMA distal to the pseudoaneurysm. Both internal and elastic laminae are preserved and intimal proliferation is unremarkable. Arterial lumen is occluded with thrombus. i HPV (× 400) of the distal SMA with EVG staining. There is not a great deal of vacuolization, but degeneration and disarrangement of the outer media (asterisks) are visible