Gallbladder varices; an unusual collateral pathway

Clinical History

A 36-year-old man, former athlete, presented with vague epigastric pain. His laboratory tests, apart from a mild decrease in his platelet count, were otherwise unremarkable. The endoscopic evaluation of the upper gastrointestinal tract revealed gastritis, small ulcers and oesophageal varices. The patient admitted illegal substances abuse during his career.

Imaging Findings

The patient was admitted by his gastroenterologist for an abdominal MRI, which revealed portal venous thrombosis, with a worm-like network of enhanced vessels in the porta hepatis and hepatoduodenal ligament, consistent with cavernous transformation. An unusual nodular enhancement of the gallbladder wall was another finding, which was further evaluated with ultrasound. The ultrasound examination detected multiple, tortuous, serpentine, anechoic structures in the gallbladder wall, that showed venous flow on Doppler imaging. It also confirmed the non-patency of the portal vein, with numerous sponge-like veins around its lumen.

Discussion

Presence of abnormal collateral vessels is one of the most sensitive and specific signs for the diagnosis of portal hypertension [1]. When blood flow in the portal vein is obstructed, either due to occlusion (as in extra-hepatic portal venous thrombosis) or distortion (as in cirrhosis), collateral pathways open up in order for the blood to by-pass the obstruction [1]. The formation of portosystemic pathways occurs due to reopening of collapsed embryonic channels or reversal of flow within existing adult veins. In patients with portal vein thrombosis though, in addition with portosystemic collaterals, porto-portal collaterals are frequently found. These porto-portal collaterals involve the paracholecystic, paracholedochal-epicholedochal and pancreaticoduodenal veins, which by-pass the occluded segment of the portal vein [1, 2]. Gallbladder varices, in particular, represent porto-portal collaterals, found in 30% of patients with portal vein thrombosis [2]. Normally, the cystic vein drains to the right portal branch. Consequently, in case the clot extends to the right portal vein, gallbladder varices develop, draining to the distal right branches of the portal vein, provided that the latter are patent.
Gallbladder varices are not related to specific symptoms themselves; the patient usually presents with symptoms attributable to the underlying disease. Their clinical significance is their propensity to bleeding during surgery [3]. The preoperative recognition and evaluation of the varices, if cholecystectomy is scheduled, is important in order to avoid hazardous complications [4].
Ultrasound is the most sensitive imaging technique for the diagnosis. Gray-scale ultrasound usually reveals a thickened gallbladder wall, with numerous serpentine, cystic structures lying in the wall and the pericholecystic bed. Colour Doppler images show venous flow in these structures, with low-velocity continuous wave, confirming the presence of varices [5]. CT most commonly shows irregular, nodular enhancement of the gallbladder wall, or multiple enhancing small vessels in the pericholecystic fat [5]. MRI can also detect the varices, but it doesn't seem to add further information compared to ultrasound and CT [5].
The fact that gallbladder varices are small, rare and usually co-exist with numerous collaterals in the porta hepatis, makes their identification rather challenging [6, 3]. They can rarely cause spontaneous haemobilia, intraabdominal bleeding or gallbladder rupture [3].
As a conclusion, varices should be considered in the differential diagnosis of gallbladder wall thickening, along with chronic cholecystitis and hyperplastic cholecystosis (Rokitansky-Aschoff sinuses) [7]. Their identification should always lead to a careful search for portal vein occlusion [7].

Differential Diagnosis List

Final Diagnosis

Gallbladder varices in chronic portal vein occlusion.

URL:	https://www.eurorad.org/case/12162
DOI:	10.1594/EURORAD/CASE.12162
ISSN:	1563-4086