—  SPECIALTY CONFERENCE  —

Liver Pathology

Case 5 - Embryonal Rhabdomyosarcoma of the Biliary Tree

J. Thomas Stocker
Uniformed Services University of the Health Sciences
Bethesda, Maryland


Click on each slide thumbnail image for an enlarged view
Clinical History:
This 4 year old girl was noted by her mother to be jaundiced but otherwise unremarkable. Laboratory findings included a total bilirubin of 5.2 mg/Dl with a direct portion of 4.9 mg/dl. CT demonstrated a mass lesion in the hilus of the liver.

Diagnosis: Embryonal Rhabdomyosarcoma of the Biliary Tree


Case 5 - Figure 1 - Low power of lesion
Case 5 - Figure 2 - Medium power of lesion


Case 5 - Figure 3 - High power of lesion. Note mitotic figures
Case 5 - Figure 4 - High power of lesion

Definition
Embryonal rhabdomyosarcoma of the biliary tree is a rare though highly malignant lesion occurring almost exclusively in children. It grows along and within the common bile duct and major hepatic ducts, producing obstruction and jaundice. Long-term survival is poor.

Although the most common sarcoma in the pediatric patient, rhabdomyosarcoma of the liver accounts for only 0.8% of all rhabdomyosarcomas and 1.0% of all liver tumors.1  The lesion is seen primarily (75% of cases) in children under 5 years of age, and rarely in those over 15 years.2-4 

Jaundice is seen as the presenting symptom in 60% to 80% of cases and may be accompanied by cholemia, pale stools, and hepatomegaly, often confused with infectious hepatitis. Other symptoms include fever, abdominal distention, nausea, and vomiting. The jaundice is reflected in moderate elevations of conjugated and unconjugated bilirubin, with total bilirubin of 1.5 to 9.0 mg/dl. Alkaline phosphatase may also be elevated along with a mild rise in SGOT. Imaging studies, including CT, MRI, ultrasonography, and cholangiography may clearly demonstrate the site of obstruction within the intrahepatic ductal structures.5 

Treatment
Treatment has aimed at surgical resection, although complete resection is possible in only 20% to 40% of patients because of extension of the tumor into the liver, regional metastasis, and local extension to the duodenum, stomach, and pancreas.1, 6, 7  Recent preoperative therapy using standard protocols for embryonal rhabdomyosarcoma has proved effective with Pollono et al reporting complete remission using a multi-drug protocol as the initial treatment of a 3-year-old girl after obtaining adequate transparietohepatic biliary drainage.] Long-term survival of approximately 20% in previous years has risen for patients treated with preoperative chemotherapy and surgical A second-look @.8 

Pathology
Grossly, the tumor often presents as a botryoid, gelatinous mass occluding the lumen of the right and left or common bile duct. The ducts proximal to the lesion are frequently dilated, and the walls of the duct containing the lesion are thickened. The tumor may extend into the liver as a soft lobulated mass.1, 9 

Microscopically, the botryoid masses within the bile ducts are covered by a layer of cuboidal epithelium (bile duct epithelium) that may be inflamed or ulcerated. Beneath the epithelium lies a dense layer of tumor cells, the upper portion of the A cambium @ layer. Cells within this area are small and hyperchromatic, with scant cytoplasm. Deeper to the bile duct epithelium the cells lie in a loose myxoid stroma and exhibit the typical features of embryonal rhabdomyosarcoma with round, spindle, or A strap @ shapes; elongate nuclei: scant acidophile cytoplasm; and frequent mitoses. As with other rhabdomyosarcomas, cross-striations may occasionally be found, but immunohistochemistry studies are consistently positive for desmin, with myoglobin and myosin identified in more differentiated cells. The tumor is usually highly vascular, and areas of recent and remote hemorrhage and acute and chronic inflammation may be found throughout the lesion. The adjacent hepatic parenchyma is often compressed, and bile may be present within canaliculi and hepatocytes.

References

  1. Stocker, J.T., Hepatic tumors in children. Clin Liver Dis, 2001. 5(1): p. 259-81, viii-ix.
  2. Donnelly, L.F., G.S. Bisset, 3rd, and D.P. Frush, Diagnosis please. Case 2: Embryonal rhabdomyosarcoma of the biliary tree. Radiology, 1998. 208(3): p. 621-3.
  3. Sanz, N., et al., Rhabdomyosarcoma of the biliary tree. Pediatr Surg Int, 1997. 12(2/3): p. 200-1.
  4. Lee, M.J., et al., Biliary tree rhabdomyosarcoma: report of one case. Chung Hua Min Kuo Hsiao Erh Ko I Hsueh Hui Tsa Chih, 1996. 37(6): p. 458-60.
  5. Roebuck, D., et al., Hepatobiliary rhabdomyosarcoma in children: diagnostic radiology. Pediatr Radiol, 1998. 28(2): p. p101-8.
  6. Ferlicot, S., et al., [Unusual site of an embryonal rhabdomyosarcoma of the mesenchymal hepatic pedicle]. Ann Pathol, 1999. 19(6): p. 521-4.
  7. Balkan, E., et al., Rabdomyosarcoma of the biliary tree. Turk J Pediatr, 1999. 41(2): p. 245-8.
  8. Pollono, D.G., et al., Rhabdomyosarcoma of extrahepatic biliary tree: initial treatment with chemotherapy and conservative surgery. Med Pediatr Oncol, 1998. 30(5): p. 290-3.
  9. Davis, G.L., J.M. Kissane, and K.G. Ishak, Embryonal rhabdomyosarcoma (sarcoma botryoides) of the biliary tree. Report of five cases and a review of the literature. Cancer, 1969. 24(2): p. 333-42.