S3039 Hepatic Undifferentiated Pleomorphic Sarcoma Mimicking Liver Abscess

Abstract

Introduction: Undifferentiated pleomorphic sarcoma (UPS) has been recognized as one of the most common malignant soft tissue tumors. It usually affects the elderly population and involves the extremities. However, hepatic UPS is rare. Fewer than 200 cases have been reported. Primary hepatic UPS occurs in late adulthood. It typically presents with a solid hepatic mass with regional lymph node involvement. Occasionally, UPS mimics hepatic infection clinically. Here we report a case of hepatic UPS, mimicking the presentations of liver abscess. Case Description/Methods: A 44-year-old female with a past medical history of hypertension presented at the emergency department (ED) for right upper abdominal pain for one week. The pain was described as dull, 5/10 on a pain scale, non-radiating, and associated with nausea, fever, and chills. The pain was worsened by sitting up and alleviated by lying down. At ED, the patient’s vital signs were within normal range. Physical examination showed right upper quadrant tenderness, without rebound, guarding, or rigidity. She was found to have slightly elevated liver enzymes and alkaline phosphate. CT of the abdomen revealed an irregular hypodense mass at the right hepatic lobe measuring 14.3 x 11.6 cm and a 2.6cm enlarged porta hepatis lymph node. The patient was admitted for further evaluation. Concerning possible liver abscess, the blood culture was collected, and the patient was treated with empiric antibiotics. Tumor markers including AFP, and CEA were within normal range. The blood culture was negative for infection. To rule out malignancy, PET scan was performed and showed a hypermetabolic mass with necrotic components in the liver. The patient underwent a liver biopsy. The pathology revealed extensively necrotic pleomorphic round cells with eosinophilic cytoplasm and variably sized, oval nuclei, indicating hepatic undifferentiated pleomorphic sarcoma. Oncology was consulted and recommended doxorubicin and ifosfamide for neoadjuvant chemotherapy. The patient was discharged to home to follow up with oncology as outpatient for chemotherapy and surgery for tumor resection. (Figure) Discussion: Hepatic UPS is a rare malignant mesenchymal tumor. Nonspecific clinical symptoms, unmarkable laboratory findings, and rapid tumor growth lead to poor prognosis. Physicians should be aware of this rare disease as a differential diagnosis for liver mass. Surgical resection is the preferred treatment. Chemotherapy could be used as neoadjuvant or adjuvant treatment to improve the survival rate.Figure 1.: a large liver mass noticed on CT of abdomen with contrast.