Rhabdomyosarcoma (RMS) is the most common soft-tissue sarcoma in the paediatric age group, ranking fourth in frequency after central nervous system tumours, neuroblastomas and nephroblastomas. Embryonal RMS of the biliary tree is considered a rare entity, with the most common clinical presentation being that of obstructive jaundice. We present the case of a 4-year-old boy who presented with hepatomegaly and obstructive jaundice. Biochemically, there was evidence of elevated ductal enzymes with conjugated hyperbilirubinaemia. The magnetic resonance imaging (MRI) features were consistent with a biliary RMS with the differential diagnosis of a choledochal cyst initially included based on the computed tomography images. The diagnosis of embryonal biliary RMS was later confirmed on histology. This case illustrates the importance of considering malignant aetiologies in paediatric cases of obstructive jaundice, as this entity is infrequently described in the literature and may mimic the appearance of a choledochal cyst. The demonstration of enhancement of intraductal material within the biliary tree on MRI and the presence of arterial waveforms within the intraductal mass on ultrasound assists in the differentiation between biliary RMS and a choledochal cyst.
Rhabdomyosarcoma (RMS) is a malignant tumour of skeletal cell morphology, with the most common sites in the paediatric population being the head and neck, genitourinary system and extremities.
A 4-year-old boy presented with a 3-month history of yellow discolouration of his eyes, dark urine and pale stools as well as a 2-month progressive history of abdominal distension. On physical examination, he was pale, had scleral icterus and the abdomen was distended with a large palpable liver. On the day of his admission, serology revealed elevated liver ductal enzymes with conjugated hyperbilirubinaemia, an elevated international normalised ratio (INR) and iron deficiency anaemia.
The abdominal ultrasound (US) demonstrated a heterogeneous periportal mass with internal flow on colour Doppler and associated dilatation of the common bile duct (CBD), cystic duct, gall bladder and intrahepatic bile ducts. A computed tomography (CT) scan of the abdomen and pelvis with an intravenous and oral contrast agent showed a large (60 mm × 45 mm × 89 mm), fusiform-shaped mass with heterogeneous contrast uptake, parallel to the expected course of the CBD (
Axial post contrast computed tomography image at the level of the origin of the superior mesenteric artery (white arrow) demonstrating a fusiform-shaped mass (black arrows) with heterogeneous contrast uptake, parallel to the expected course of the common bile duct. Associated findings of prominent intrahepatic bile ducts and a dilated pancreatic duct.
Coronal post contrast computed tomography image demonstrating a heterogeneous mass within the common bile duct (black arrows) with the superior aspect not separable from the adjacent porta hepatis or proximal central bile ducts (white arrow).
Magnetic resonance imaging (MRI) of the abdomen and magnetic resonance cholangiopancreatography (MRCP) with contrast were of added value in better delineating the origin and extent of the mass already suspected of being bile duct in origin on CT. The lesion filled the dilated CBD (
Coronal T2-weighted magnetic resonance imaging illustrating a fusiform-shaped mass arising within the common bile duct (black arrows) extending superiorly to the level of the porta hepatis. This mass is largely hyperintense on T2-weighted imaging with patchy regions of hypointensity, likely secondary to coagulative necrosis.
Axial T2-weighted magnetic resonance imaging demonstrating asymmetric mural thickening of the common bile duct (black arrows) with dilation of the gallbladder and a small calculus (white arrow) within the dilated cystic duct.
Coronal magnetic resonance cholangiopancreatography shows distension of the gallbladder with dilated intrahepatic bile ducts, cystic duct and pancreatic duct. The common bile duct is dilated with a large filling defect (black arrows) and no normal calibre common bile duct is visualised distally.
The MRI features were consistent with a biliary RMS with the differential diagnosis of a choledochal cyst initially included based on the CT images. The patient was taken to theatre where the ascites was drained and the peritoneal cavity inspected. A solid heterogeneous mass was found within the dilated CBD. In addition, there was a periportal lymph node mass as well as peritoneal wall deposits. Multiple tissue biopsies were sent off for histopathological evaluation.
Microscopy confirmed the presence of a high-grade malignant tumour consisting of primitive mesenchymal cells of varying phases of myogenesis with a variable content of rhabdomyoblasts. The immunohistochemical features were in keeping with embryonal RMS with positive stains of Periodic Acid-Schiff (PAS), desmin, myogenin and myoD1. There were representative sections that showed that the tumour infiltrated into the fibrovascular connective tissue as well as evidence of angiolymphatic infiltration. Perinodal soft-tissue extension was noted; however, no biliary mucosa was present for assessment.
The immunophenotypic features were in keeping with embroyonal RMS with the probability of bile tract origin based on imaging and intraoperative findings. The patient then received post-operative chemotherapy and was initiated on cycle 1 of the VICE protocol which included vincristine, isosfamide, carboplatin and etoposide. Unfortunately, a few days after initiating treatment, the patient became very ill in the ward. His abdomen became very tense and distended which caused splinting of the diaphragm. He subsequently developed respiratory distress and demised.
Rhabdomyosarcoma is the most common soft-tissue sarcoma in the paediatric age group and represents 5% – 10% of all malignant solid tumours in childhood.
Embryonal RMS was first described by Wilks and Moxon in 1875 on the basis of the typical location and gross description of the tumour.
The International Classification of Rhabdomyosarcoma (ICR) provides a prognostically relevant classification that includes histological subtypes as being of superior prognosis (botyroid and spindle cell RMS), intermediate prognosis (typical embryonal RMS) and poor prognosis (alveolar RMS).
The median age of presentation of embryonal RMS is 3 years, with a slight male predominance.
Obstructive jaundice in the paediatric population beyond the neonatal period may be secondary to choledochal cysts, choledocholithiasis, strictures as a result of chronic cholangitis and rarely neoplasms such as biliary RMS.
Abdominal US is typically the initial imaging study performed in any patient presenting with obstructive jaundice. In our patient, this demonstrated a soft-tissue mass in the region of the porta hepatis with adjacent mass effect and intrahepatic bile duct dilatation. Computed tomography and MRI/MRCP was then used to better delineate the site of origin, assess the tumour extent and evaluate for metastatic lesions. Magnetic resonance imaging and MRCP confirmed a mass originating within the biliary system that enhanced heterogeneously, followed the signal characteristics of muscle on T1-weighted imaging and was hyperintense on T2WI. Haemorrhage and necrosis may be apparent in larger lesions of biliary RMS and the imaging features of central tumour necrosis may mimic the appearance of a choledochal cyst.
Previous case reports have alluded that biliary RMS is often misdiagnosed as a choledochal cyst on imaging.
The current treatment modalities include a combination of surgical removal, radiation and chemotherapy.
Biliary RMS is a rare entity but should be included in the differential diagnosis of any child presenting with obstructive jaundice.
The authors declare that they have no financial or personal relationships that may have inappropriately influenced them in writing this article.
D.M. was responsible for the review of literature, review of the imaging studies as well as the write-up and preparation of the case report as per journal requirements. H.D.L. (intern) compiled the clinical and surgical notes, imaging reports and histology results. N.M. was responsible for the diagnosis of the case, interpretation of the imaging studies and editing of the final article. D.M. and H.D.L. share joint first co-authorship.