Teaching Case

A 63-year-old female with uncontrolled diabetes and hypertension presented to the emergency department with sudden abdominal pain, jaundice and malaise. Laboratory results revealed elevated bilirubin and liver enzymes.

Severe intrahepatic biliary dilation with multiple calcifications was found by ultrasonography (Figures 1a 1b). Contrast-enhanced abdominal CT scan demonstrated an irregular hypodense lesion infiltrating the intrahepatic biliary ducts with several small calcifications within it and upstream bile duct dilatation. (Figures 2a, 2b)

This mass exerted compression over the portal vein, with multiple gastroesophageal varicose veins arising from it. With these findings, differential diagnoses were intraductal papillary mucinous neoplasm bile duct (IPMN-B), Caroli disease, perihilar cholangiocarcinoma and metastasis.

MRI after the CT scan proved a heterogeneously hyperintense filling defect of the bile ducts on T2-weighted images that showed an early arterial enhancement on fat-saturated T1-weighted image, with high signal intensity on DWI and low ADC. (Figures 3a, 3b, 3c, 4a, 4b)

No pathological SUV was found in PET-SCAN (Figure 5). Finally and after performing a gross-needle biopsy guided through CT imaging the final diagnosis was intraductal papillary mucinous neoplasm of the bile duct. (Figure 6a, 6b, 6c). The patient was not candidate for surgical resection and received chemotherapy instead.

Intraductal papillary mucinous neoplasm of the biliary tract (IPMN-B) is a rare mucin-producing tumour characterised by intraluminal papillary masses that may cause bile duct obstruction and dilatation. [1]

This pathological entity seems to have a progressive course from a premalignant phase with low-grade dysplasia to high-grade dysplasia and finally to a malignant final phase of invasive carcinoma involving inactivation of TP53 and p16. [2] The presence of ovarian-like stroma has been established to define the diagnosis of mucinous cystic neoplasm of the liver. [3]

It is considered as a precursor lesion of cholangiocarcinoma, with typically limited distribution to the bile duct mucosa and with a favourable long-term prognosis after surgical resection. Asian countries have reported the highest incidence, being endemic hepatolithiasis and clonorchiasis infections the most important risk factors.(4)

Imaging features vary according to the intraductal extension and the degree of mucin production. MRI has the highest sensitivity demonstrating through T2-weighted images the papillary pattern with signal distortion due to the bile/mucin content of the lesion [5]. There have been other reports of this type of tumour but several calcifications within the biliary ducts is an uncommon feature on imaging tests. (6, 7, 8)

This type of tumours may show a solid pattern with restriction on DWI and low ADC. Enhancement may be similar to that of the hepatic parenchyma in the arterial phase. [4] Absence of fibrous tissue, explains the typical lack of enhancement on delayed imaging, which is an important discriminating feature compared to cholangiocarcinoma.

The treatment of choice is wide resection and although postoperative recurrence is a possibility, negative margin after an accurate procedure may be curative [5].