Introduction Ascariasis is the most common helminthic infection due to infestation by the roundworm Ascaris lumbricoides. It is prevalent mainly among female children, aged 2–10 years. In humans, the parasite is found mostly in the small bowel. Hepatobiliary and pancreatic ascariasis can occur due to migration of the adult, leading to serious complications like acute cholangitis or pancreatitis and hepatic abscess, intrahepatic duct calculi due to recurrent biliary invasion.

Case-report We describe the case of a 3-year-old girl who, during a period of two years, suffered from three episodes of cholestatic hepatitis and acute pancreatitis due to obstruction of the biliary and pancreatic ducts. The symptoms were similar each time: anorexia, abdominal distension and upper abdominal tenderness, intermittent acholic stools and jaundice, urticaria on the lower limbs. Extensive work-up for infections and autoimmune hepatitis was unremarkable.

During her first hospitalisation, the abdominal ultrasonography (US) and magnetic resonance cholangiopancreatography (MRCP) showed marked dilatation of the extrahepatic biliary duct, echogenic sludge within the gallbladder, pancreas enlargement and a dilated pancreatic duct. She was known to have had recent parasitosis. Due to treatment with albendazole, she eliminated Ascaris lumbricoides worms. Biliary sphincterotomy via endoscopic retrograde cholangiopancreatography (ERCP) was performed, evacuating the sludge and calculi most probably of parasitic origin.

On her third admission, there was no history of recent parasitic infection. The MRCP findings were similar to the first, but also detected a 5 mm filling defect at the distal common bile duct (CBD). Her condition slowly ameliorated, but after 6 days ERCP was performed revealing no lacunar areas, only a dilated CBD. Thus, the highest probability is that the obstruction was due to parasitic remnants being spontaneously eliminated.

Conclusions Parasitic diseases can be a diagnostic challenge and sometimes may not be included in the initial differential diagnosis. Because they can imitate infections by other agents or neoplastic processes, they can be mistaken as such. Treatment options include conservative treatment, usually effective, ERCP and surgery. Maintaining a high level of suspicion to diagnose biliary ascariasis is paramount for proper management and avoiding long-term complications.