Undifferentiated Embryonal Sarcoma of the Liver with Epithelioid Features: A Case Report of an Exceptional Histological Heterogeneity among Rare Diseases.

INTRODUCTION:Undifferentiated embryonal sarcoma of the liver (UESL) is a rare and aggressive malignant tumor, with nonspecific clinical symptoms and radiological features. Less than 150 cases have been reported in adults across the world. PRESENTATION OF CASE:We report a case of an extremely rare subtype of UESL with epithelioid features in a 29-year-old woman, presenting as a cystic lesion of 27 × 17 cm, completely subverting the right hepatic lobe. She underwent a right hepatectomy with anterior approach, complete hilum lymphadenectomy and partial diaphragmatic resection for local infiltration, followed by systemic chemotherapy. She remains with no evidence of disease and liver mass has been restored after 6 months. DISCUSSION:The present case report represents the second case of UESL with epithelioid features described across the world. The immunohistochemical expression pattern, cytokeratin (CK)19 + and CK7 -, strongly suggests an origin of this epithelioid component from native biliary cells and not from a reshaped ductal plate. Due to the rarity of this form, to date it is impossible to define the prognostic impact of this subtype of UESL, and treatment remains challenging. CONCLUSION:UESL is associated with a poor prognosis, especially in adults, but a comprehensive and multidisciplinary treatment based on radical resection and adjuvant therapy may provide a survival benefit. Surgical excision with negative margins remains mandatory to diagnose and treat UESL.