Purpose or Case Report: Rhabdomyosarcoma is a common pediatric soft tissue cancer with about 31% of cases in the urinary tract and 25% of cases in the head and neck. Although rhabdomyosarcomas are common, primary intrahepatic rhabdomyosarcomas are very rare and have a poor prognosis. In fact, there have only been 20 reported cases from 1956 through 2017, and the mean survival time of 9.25 months.

A 3-year-old male with a history of constipation presented with a 3-days of low-grade fevers of 99-100 F, periumbilical pain, and anorexia. On physical exam, there was a palpable, tender RUQ mass. Labs showed an elevated ALT of 159, AST of 179, and alkaline phosphatase of 748. A radiograph of the abdomen showed a soft tissue opacity in the right upper quadrant which displaced the large and small bowel loops. Further imaging included an ultrasound, CT, and MRI. The ultrasound confirmed a large mostly solid mass in the right hepatic lobe. CT imaging showed a large heterogeneous liver mass measuring 10.5 x 10.0 x 14.0 cm. The mass extended superiorly to the dome of the liver, involved the caudate lobe, and compressed the IVC. An indeterminate lucency of the right femoral neck was also noted. A follow up MRI showed that the liver mass displaced the hepatic veins, main portal vein and right portal vein. Additionally, innumerable lesions were found on the axial skeleton and periportal lymphadenopathy was seen suggesting metastasis. PET scan further confirmed bony metastasis of the right femur. Initially, hepatoblastoma was highest on the differential. However, liver wedge biopsy showed myxoid spindle cell areas and small round blue cell areas. These findings favored the diagnosis of rhabdomyosarcoma as opposed to hepatoblastoma which would have had an epithelial component. Bone marrow biopsy further confirmed metastasis. As a result of this diagnosis, the patient was started on vincristine, dactinomycin, cyclophosphamide. Pain was controlled with morphine and acetaminophen. Nausea was controlled with Ativan, Zofran, Reglan, and Benadryl. The patient’s abdominal distension and constipation responded well to a stool regimen and multiple enemas. The patient was discharged in stable condition with oncology follow up.

Hepatic rhabdomyosarcoma is a rare malignancy, and early diagnosis and treatment has been beneficial in prolongation of mean survival time. Diagnostic imaging modalities and pathology findings are an essential part of the work up and can be used to guide the treatment and management.
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