Imaging findings in a giant hepatic artery aneurysm.

HH Parmar, JJ Shah, BB Shah, DD Patkar, RR Varma 
 Department of Radiology, Seth G. S. Medical College and K. E. M. Hospital, Parel, Mumbai - 400 012, India. , India

Correspondence Address:
H H Parmar
Department of Radiology, Seth G. S. Medical College and K. E. M. Hospital, Parel, Mumbai - 400 012, India.
India

Full Text

Giant hepatic artery aneurysms are rare. Patients are often asymptomatic and present late[1]. However, awareness of this condition is important as there is a high probability of these aneurysms rupturing and presenting as acute abdomen. Until now, diagnosis was usually made based on angiography findings. However, the use of the modern imaging techniques like colour Doppler (CD) and dual phase helical computerised scanning can now reliably provide similar information. We present a case of a giant aneurysm of the hepatic artery diagnosed on the basis of CD and the computerised tomographic (CT) scan findings.

::   Case report

A 40-year-old man was referred for vague, dull-aching pain in the abdomen for the last five months. Ultrasonography (USG) of the abdomen showed a large, well defined, rounded, hypoechoic mass lesion in the region of porta hepatis, measuring approximately 7 x 9 cms. It revealed an eccentric rounded anechoic area within it, which showed flow on CD examination and was suggestive of flow lumen. Peripheral to this flow lumen, rest of the lumen revealed somewhat homogenous echogenic lesion, which did not reveal any flow on CD examination. The entire lesion was lined by a very echogenic lining, suggestive of calcification of its walls. CD examination revealed communication of this lesion with intrahepatic arterial radicals. The portal vein and its radicals did not reveal any abnormality. The duplex examination revealed typical arterial flow pattern. Rest of the abdominal ultrasound including hepatobiliary system was normal.

Non-enhanced arterial and portal venous phase helical CT scan of the liver and upper abdomen was performed with slice thickness of 5-8 mm. Unenhanced scan showed a large, hypodense, well demarcated mass at the porta with calcified walls. After intravenous administration of 50-60 ml of bolus of contrast medium and scanning in early arterial phase (15-40 seconds) marked enhancement of the lumen of the lesion was noted along the course of the hepatic artery, from its origin from the coeliac artery. The non-enhancing portion of the lesion was suggestive of partial thrombosis of the aneurysm. CT angiography and reconstructive images showed presence of a large aneurysm arising from the hepatic artery in its extrahepatic region. The aneurysm measured approximately 7 x 15 cms and extended from the point of origin of the hepatic artery right till the porta. The patient underwent surgical correction of the aneurysm. Histopathology of the specimen was suggestive of atheromatous affection.

::   Discussion

The hepatic artery is the fourth most common site of intra-abdominal aneurysm from any cause following infra renal aorta, iliac and the splenic artery[2]. 80 % of the hepatic artery aneurysms are extra-hepatic and of these 63% affect the common hepatic artery[3],[4]. The extra-hepatic aneurysms have high incidence of rupture compared to the intra-hepatic aneurysms and have an associated mortality rate of 82%[2],[3]. The disease is often asymptomatic and the average age of presentation is often late in fourth and fifth decade of life[3],[5]. 65% of the cases have been reported in the males[3],[4]. There are various aetiologies for hepatic artery aneurysms. Atherosclerosis, infection (often mycotic), and trauma account for most of these aneurysms. Pancreatitis, hereditary telangiectasias, cystic medial necrosis, vasculitis, liver abscess and tuberculosis are less common causes[2],[6].

Patients usually present with complaints of abdominal pain, lump in abdomen and rarely as gastrointestinal haemorrhage or obstructive jaundice[4],[5]. The classic triad of abdominal pain, haemobilia and obstructive jaundice is seen in only 30% of the patients[3],[4]. On examination abdominal bruit or a pulsatile mass may be found. The aneurysm may rupture into the peritoneal cavity, duodenum, portal vein and stomach or rarely into the gall bladder[2],[3].

USG of the abdomen usually shows a hypoechoic area at the porta, but it is not confirmatory. CD will however show arterial or turbulent flow in the lesion, suggestive of it being a mass of vascular origin. Until now, angiography was considered to be the gold standard for diagnosing hepatic artery aneurysms. However, the use of CT angiography by dual phase spiral/helical scan and newer breath holding MR imaging can provide the same type of information with reliable accuracy[7]. In our patient surgery was undertaken on the basis of these imaging findings and preoperative angiography was avoided. Treatment of these aneurysms is usually in the form of ligation and surgical correction for the extra-hepatic aneurysms and transcatheter embolisation for the intra-hepatic ones[7],[8].

In conclusion, giant hepatic aneurysms are extremely rare with very few cases reported so far. However, the rarity of lesions must not exclude it from the diagnostic protocol of the abdominal masses. USG study must be accompanied by a CD and CT scan must be done using a contrast medium.

References