Intrahepatic gallbladder duplication mimicking a hepatic cyst: A case report

Abstract

Gallbladder duplication is a rare anomaly of the biliary tree. Implications of misdiagnosis include unwarranted surgery and morbidity such as when liver resections are done suspecting cystic intraductal papillary neoplasm of the bile duct. The use of appropriate imaging, when suspected, facilitates diagnosis and avoids adverse surgical outcomes. We describe a case of an intrahepatic duplicate gallbladder containing calculi detected incidentally during a Focused Assessment Sonography for Trauma after a blunt trauma.

Introduction

Accessory gallbladders are uncommon, occurring in 1 in 4000 live births or 0.02%–0.03% of adults from postmortem and imaging studies, respectively. ¹ An accessory gallbladder may rarely be situated in the intrahepatic position. Sonographic and computed tomography (CT) or magnetic resonance cholangio pancreatography (MRCP) characteristics of this variant may mimic intrahepatic lesions such as cystic intraductal papillary neoplasms of the bile duct^2,3 or focal Caroli disease resulting in diagnostic challenges. Clinico-radiological misinterpretation may lead to unwarranted surgery and postsurgical morbidity.^4,5 We report on a patient incidentally found to have an accessory intrahepatic gallbladder during Focused Assessment Sonography for Trauma (FAST) in the emergency department.

Case presentation

A 30-year-old female presented to emergency department (ED) following blunt abdominal trauma. She had no external injuries and was hemodynamically stable. The FAST performed at the ED was normal, and she was discharged after period of observation. During the FAST, a cystic lesion with internal calcification was noted in segment IVA of the liver. Her past medical history was unremarkable with no suggestion of biliary pain, and her liver biochemistry was normal. She subsequently underwent abdominal ultrasonography, CT, and magnetic resonance imaging (MRI)/MRCP to characterize the lesion.

Ultrasonography showed a cystic liver lesion with multiple calcifications in addition to a gallbladder of normal appearance (Figure 1). CT was suggestive of a gall bladder diverticulum with calcification (Figures 2 and 3). MRI and MRCP demonstrated an intrahepatic gallbladder with multiple calculi and of otherwise normal morphology. The cystic duct of the intrahepatic gallbladder opened to the common hepatic duct (CHD) (Figures 4 and 5). The extrahepatic gallbladder was also present with a separate cystic duct opening to the CHD. The findings were compatible with an H-type accessory gallbladder. Another incidental finding was a left pelvic kidney. In view of her current asymptomatic status, no intervention was prescribed.

Figure 1.

Ultrasound abdomen image shows intrahepatic GB with multiple calculi and extra hepatic GB.

Figure 2.

Contrast-enhanced CT abdomen (70 s) axial image shows extrahepatic GB.

Figure 3.

Contrast-enhanced CT abdomen (70 s) axial image shows intrahepatic GB.

Figure 4.

MRCP image shows accessory intrahepatic GB and extra hepatic GB opens to CHD separately.

Figure 5.

MRI-STIR image shows accessory intrahepatic GB with multiple GB calculi and an incidental finding of malrotated left pelvic kidney.

Discussion

Gallbladder duplication results from the division and formation of an extra gallbladder primordium during the embryonic period. ¹ During organogenesis, the caudal bud or the pars cystica gives rise to the gallbladder, cystic duct, and the common bile duct. Abnormalities in the migration of the pars cystica result in anomalous positions of the gallbladder. ² In true duplications, both gallbladders may share a common cystic duct or have their own duct. Harlaftis has classified double gall bladders into three types (Types I, II, and III); ⁶ those with separate cystic ducts leading to the CHD (H-type) and those with a common cystic duct entering the CHD (Y type).

Ectopic locations described include intrahepatic, transverse and retroplaced, lesser omentum, falciform ligament, retroduodenal area, abdominal wall muscles, and intrathoracic. The intrahepatic location, the second commonest ectopic site, may impair the biliary drainage resulting in biliary stasis and cholelithiasis. ⁷

Ultrasonography is incapable of differentiating intrahepatic gallbladder duplications from mimicking lesions such as a Phrygian capped gallbladder, Todani type II choledochal cysts, ⁸ gallbladder diverticuli, cystic intraductal papillary neoplasms of the bile duct, and localized Caroli’s disease. ⁹ The sensitivity of ultrasonography and CT in diagnosing duplicated gallbladders is similar at about 60%. ² This rises to 96% for MRCP, and hence, this is the imaging modality of choice when the suspicion of a gallbladder anomaly exists. ⁸

Implications of misdiagnosis include unwarranted surgery and morbidity such as when liver resections are done suspecting cystic intraductal papillary neoplasm of the bile duct. A duplicated intrahepatic gallbladder missed at cholecystectomy may result in bile leaks and recurrent symptoms after a cholecystectomy. ¹⁰

Conclusion

This case seeks to raise the awareness of an anomaly of the biliary tree for radiologists and surgeons. Although rare, intrahepatic gallbladder duplication has important clinical and surgical implications. Awareness of this variation enables the surgeon to plan ahead for a potentially challenging cholecystectomy in the event of symptomatic cholelithiasis.