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A case of a right accessory hepatic duct diagnosed during a Whipple procedure

Highlights • Accessory right hepatic duct, that merged to the common bile duct.• The accessory right hepatic duct drains the posterior segments of the right hepatic lobe.• A detailed mapping of the bile tree is essential especially before major procedures.


Introduction
Right and left hepatic duct converges at the liver to constitute the common hepatic duct (CHD). The right hepatic duct (RHD) drains the right segment of the liver (V, VI, VII, VIII), while the left hepatic duct (LHD) drains segments II, III and IV that constitute the left liver. Normal constitution of biliary confluence is reported in 72% of patients [1]. Anatomical variations of the intra-hepatic and extra-hepatic biliary tree are common and can be found in almost 28%. We present a rare case of an accessory right posterior sectoral duct that merges into the common bile duct that recognized intraoperatively during a Whipple procedure, found in 16% of patients [2]. This case report is in line with the SCARE criteria [9]

Case report
A 78-year-old caucasian male patient presented at the Emergency Department with painless obstructive jaundice. Laboratory blood tests revealed increased values of total bilirubin (14.41 mg/dL), direct bilirubin (10 mg/dL), ALP (397 mg/dL) and ␥-GT (1104 mg/dL). The patient submitted for diagnostic reasons to an upper and lower abdominal CT scan. The CT scan revealed a mass in the pancreatic head with mean diameter about 2 cm, dilatation of the main pancreatic duct, and coexisting paraortic and gastroduodenal lymph nodes of 6 mm maximum diameter that were possibly infiltrated (Fig. 1). The clinical, laboratory and imaging findings suggested obstructive jaundice due to pancreatic head tumor and the oncological council decided that Whipple procedure is the most appropriate treatment for the patient. Unfortunately, intraoperatively was found that the mass infiltrated the upper mesenteric artery and the portal vein and couldn't be excised. Therefore, a palliative operation was performed in order to ensure adequate drain of the biliary tree and to prevent future obstruction of the gastrointestinal tract. More specifically a cholecystectomy was performed alongside with a biliary-intestinal anastomosis, and hemigastrectomy with gastrointestinal anastomosis. However, during the biliary-intestinal anastomosis, a right accessory hep-  atic duct was found which drained posteriorly to the common bile duct, and consequently a double gastrointestinal anastomosis was performed.
The patient's postoperative course was uneventful and he was discharged from the hospital the 7th postoperative day. Two weeks later a magnetic resonance chalangiopancreatography (MRCP) was performed for diagnostic reasons which confirmed the intraoperative diagnosis. MRCP revealed the course of the right accessory hepatic duct and defined that the accessory duct drained the posterior segment of the right lobe (VI, VII) (Fig. 2).
A year after the operation the patient is under chemotherapy without obstruction of the bile tree.

Discussion
Definition of an accessory right hepatic duct, requires the existence of a main right hepatic duct, otherwise the definition of "accessory" is inconclusive [3,4]. Searching the relative bibliography in Pubmed and Scopus can confirm that this anatomical variation is quite rare. According to published studies, such as Matsunaga et al. [5], there are four types of right accessory hepatic duct, and our case is described in 5%. Some other authors like Nakamura et al. [6] and Varotti et al. [7], classify six types of anatomical variations, and our case is identified in only 2,6% of the cases. A recent study performed by Ishii et al which evaluates the accessory hepatic ducts preoperatively, proposes a five type classification (I-V) of an accessory hepatic duct. In this study right accessory hepatic duct that drains in the common bile duct anteriorly was found in only one case (2%) [8]. All the above mentioned data suggest that right accessory hepatic duct is a relatively rare normal variation of the biliary tree, that may possess a significant role during liver interventions.

Conclusion
Although some of the variations of the intra-and extra-hepatic biliary system may be relatively rare, in patients that will undergo major interventions in the hepato-biliary-pancreatic region a preoperative thorough knowledge of the biliary system by MRCP or DIC-CT may prevent intra-or postoperative complications.

Conflict of interest statement
No conflict of interest.

Sources of funding
No sponsors to declare.

Ethical approval
Ethical approval is not needed for this case report as patient consent and we are not trialing a new device.

Consent
Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request.

Registration of research studies
N/A.

Provenance and peer review
Not commissioned, externally peer-reviewed.