Incidental double duct sign: Should we be worried? Results from a long-term follow-up study.

Backgrounds/aims: Double duct sign (DDS) (dilated common bile and pancreatic duct) is synonymous with pancreatic head/peri-ampullary tumor (PHPAT). There is limited evidence on whether incidental DDS (I-DDS) is associated with an increased risk of malignancy. This study aimed to evaluate 5-year outcomes of I-DDS.

Methods: Patients were categorized according to their risk of malignancy. 'Low-risk' patients, including those with I-DDS between 2010 and 2015, were analyzed in this study. The primary outcome was incidence of PHPAT within five years of identification of DDS. Histology results from endoscopic ultrasound-guided biopsy were considered diagnostic. Secondary outcomes were incidence of benign causes, extent of follow-up investigations, and clinical indicators of malignancy in patients with DDS.

Results: Among 103 patients with DDS, 20 had I-DDS. Subsequent follow-up of these 20 patients found no patient with PHPAT, two (10%) patients with chronic pancreatitis, and 18 (90%) patients with no cause found. The median follow-up duration for 'low-risk' patients was 7.3 years (range, 6-11 years). The mean number of follow-up investigations per patient was two (range, 0-9). Investigations included computed tomography (n = 27), magnetic resonance cholangiopancreatography (n = 23), endoscopy (n = 16), and ultrasound (n = 14). Patients with jaundice were more likely to have malignancy (p < 0.01). Those with abdominal pain were more likely to have a benign cause (p < 0.01). Hyperbilirubinemia and/or deranged liver enzymes and raised CA19-9 were more likely to be associated with PHPAT (p < 0.01).

Conclusions: Patients with I-DDS have a low risk of developing PHPAT within five years.