Abstract
INTRODUCTION: Undifferentiated embryonal sarcoma of the liver (UESL) is a rare form of liver malignancy, with most cases reported in the pediatric population. This disease is extremely uncommon in adults. Herein, we report the first case of UESL with epithelioid features in an adult patient. PATIENT CONCERNS: A 50-year-old man was admitted to our hospital due to epigastric pain. DIAGNOSIS AND INTERVENTIONS: Computed tomography and magnetic resonance imaging revealed a space-occupying lesion in the right lobe of the liver. A right hemihepatectomy was performed. Postoperative pathological and immunohistochemical examinations confirmed the diagnosis of UESL and features of epithelioid differentiation. OUTCOMES: The patient recovered well and refused adjuvant therapy. Unfortunately, the patient died of tumor recurrence 3 months after hospital discharge. CONCLUSION: UESL is a rare form of liver cancer, with most cases reported in the pediatric population. This case study highlights an extremely uncommon case of UESL with epithelioid features and a very poor prognosis. The findings suggest that complete intraoperative resection and postoperative adjuvant therapy should be considered to improve the prognosis of adult patients with UESL with epithelioid features.