Embryonal biliary rhabdomyosarcoma in a 4-year-old female: a case report

Introduction: Embryonal biliary rhabdomyosarcoma (EBRMS) is an exceptionally rare pediatric malignancy originating from the biliary tract. Due to its nonspecific presentation-jaundice, abdominal pain, and biliary obstruction-it often shares the clinical picture with more common hepatobiliary disorders such as hepatoblastoma or choledochal cysts, leading to diagnostic delays. Case presentation: A previously healthy 4-year-old girl presented with progressive jaundice, pale stools, and dark urine, initially diagnosed as amebiasis. The persistence of symptoms led to further evaluation, revealing hepatomegaly and a porta hepatis mass. Laboratory findings indicated obstructive jaundice with markedly elevated bilirubin and liver enzyme levels. Imaging included contrast-enhanced CT, which revealed a hypodense, poorly enhancing mass occupying the porta hepatis, encasing key vessels such as the main portal veins, celiac trunk, and hepatic arteries, and leading to intrahepatic biliary dilation. Multiple enlarged lymph nodes were also observed. Porta hepatic core needle biopsy and histopathological analysis confirmed EBRMS, immunohistochemically positive for desmin and myogenin. Given the severity of biliary obstruction, percutaneous biliary drainage was performed before initiating chemotherapy. The patient received 11 cycles of a modified VAC regimen (vincristine, actinomycin D, and cyclophosphamide), with initial dose adjustments made due to her unstable clinical status, including omission of vincristine, a 25 % reduction in actinomycin D, and a 50 % reduction in cyclophosphamide. Full-dose chemotherapy was resumed after her condition stabilized. She also underwent intensity-modulated radiotherapy (41.4 Gy). She achieved complete tumor regression, normalization of liver function, and long-term remission. Follow-up CT after two years showed stable residual soft tissue thickening at the porta hepatis, with no signs of recurrent or progressive disease. Conclusion: Despite its rarity, EBRMS and other biliary tree tumors should be considered in the differential diagnosis of children presenting with cholestasis. Early imaging studies, such as ultrasound, are critical to avoid diagnostic delays and ensure timely intervention.