PMC3295406_01
(a) Pulsatile subcutaneous mass on the upper lateral border of the left orbital arch. (b) Cross section of zygomatic orbital artery aneurysm at preoperative echo color Doppler.
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Physical examination revealed a small pulsatile mass on the upper lateral border of the left orbital arch (Figure 1(a)); the swelling was nontender and elastic and the overlying skin was slightly inflamed. Echo color Doppler demonstrated triphasic flow at the lesion site, which was hypoechogenic compared to the surrounding region; the true lumen was only partially occluded by an apparently recent thrombus (Figure 1(b)).
(a) 3D CT scan reconstruction showing the aneurysm of the zygomatic orbital artery, a branch of the left superficial temporal artery (arrow). STA denotes superficial temporal artery; ZOA zygomatic orbital artery, (b) Angio-CT scan of the aneurysm (approximately 8.45 x 5.7 mm).
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An atypical presentation of Horton's arteritis was initially considered preoperatively, but was ruled out due to the absence of inflammatory cells at histologic examination. 3D angio-computed tomography (CT) of the intracranial and extracranial vessels and the aortic arch showed an aneurysm of a branch of the left STA, anatomically identified as the zygomatic orbital artery, measuring about 8.4 x 5.7 mm (Figures 2(a) and 2(b)).
(a) Excision of the aneurysm, (b) resected aneurysm, (c) microphotograph of the resected mass. L: lumen filled with fresh, organized thrombus; W: wall of the aneurysm consisting of the intima, media, and adventitia.
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Aneurysmectomy under local anesthesia was performed (Figures 3(a) and 3(b)) through a small incision at the upper margin of the zygomatic arch, paying great attention in avoiding to injure the auriculotemporal nerve which passes nearby. Histology and immuno-histochemical analysis of the surgical specimen confirmed the diagnosis of a fusiform aneurysm (Figure 3(c)); there was no atherosclerotic degeneration; the lumen was found to contain a recent thrombus but without inflammatory cells; an histologic pattern typical of Horton's arteritis or of other types of inflammatory arteritis of was ruled out.