Clinico-radiological attributes of abnormal pancreaticobiliary junction

To evaluate the prevalence of abnormal pancreaticobiliary junction (APBJ) on Magnetic Resonance Cholangio-Pancreatography (MRCP) in patients with and without choledochal cyst (CDC), and study their clinico-radiological profile.

We have retrospectively screened all MRCP studies (n = 13,482) done in our Radiology department over 18 months and documented the presence and type of APBJ (any length of extra-duodenal common channel) and CDC, other co-existing pancreaticobiliary abnormalities including complications.

Prevalence of APBJ was 0.5% (n = 67) with 77% of them showing CDC (52/67) while only 0.85% of patients without APBJ have CDC (p value < 0.0001). The most common type of CDC associated with APBJ was Todani Type I (86%) followed by type IV (14%). 31% of CDC patients had APBJ (52 out of 165) while the majority of patients with CDC (69%) did not have APBJ. Between the CDC (n = 52) and non-CDC (n = 15) subgroups of APBJ, there was statistically significant difference in the age (25 vs. 40 years, p value 0.003), gender, length of common channel (14.4 ± 6 mm vs. 10.6 ± 5 mm, p value 0.03), JSPBM type of APBJ and the risk of biliary malignancy (1.9% vs. 26.7%, p value 0.008, Odds ratio 13.8). Although idiopathic pancreatitis was also more common in the non-CDC subgroup, this difference was not statistically significant. There was no statistical correlation between the length of common channel and occurrence of CDC, biliary calculi, malignancy or pancreatitis.

Any length of common pancreaticobiliary channel outside the duodenal wall must be considered as APBJ; there is no correlation between the actual length of common channel and occurrence of its complications. The often overlooked and underdiagnosed subgroup of APBJ without biliary dilatation are 13.8 times more likely to develop biliary malignancy than the CDC group. We therefore suggest a necessary shift in surveillance strategies and advocate for routine screening of patients with APBJ for any biliary malignancy, even in the absence of CDC, and perhaps subject them to prophylactic cholecystectomy.