Embryonal Sarcoma of the Liver in the Adult: Challenges in the Diagnosis of a Rare Entity.

Introduction: Embryonal sarcoma of the liver (ESL) is a rare neoplasm of the liver occurring mainly in paediatric ages. Making the correct diagnosis can be challenging as the laboratory and radiological findings that are often nonspecific, and the tumour immunophenotype is poorly defined and even somewhat variable. Case Presentation: A large epigastric mass was detected in a computerized tomography scan of a 43-year-old woman presenting with abdominal pain and bloating. The mass was biopsied and submitted to histopathological study. Microscopically the tumour had sarcomatoid features and showed multinucleated cells with periodic acid-Schiff (PAS)-positive globules. Immunostaining revealed positivity for vimentin, CD10, glypican-3, and α1-antitrypsin and negativity for keratins, muscle, adipocytic, and melanocytic differentiation markers. The patient was then submitted to a left hepatectomy with similar histological findings. Discussion: ESL in adults is a rarity and its diagnosis requires the exclusion of other entities. While some microscopic features are very common, they remain nonspecific. The main feature is the presence of multinucleated cells with PAS-positive hyaline globules. While ancillary testing is key, the immunophenotype also lacks specificity and ESL may have variable staining for glypican-3 and epithelial or muscle differentiation markers. Although it has been described for more than 3 decades, the prognosis and optimal treatment are still not well defined, but surgery has yielded favourable results.