Teratoid hepatoblastoma with small cell undifferentiated histology in polysplenia patient: a case report

Abstract Introduction/Objective Hepatoblastoma (HB) with teratoid is a uncommon variant of mixed epithelial and mesenchymal components. Conversely, HB with small cell undifferentiated (SCUD) is extremely rare, with only nine documented cases showing retained INI-1 expression in the literature. The prognosis of SCUD remains debatable. In this report, we describe the first case of combined teratoid HB with a SCUD component that preserved INI-1 expression with a favorable outcome. Methods/Case Report A 2-year-old girl with polysplenia syndrome presented with a right liver mass detected during ultrasound screening. The alpha fetoprotein levels were significantly elevated to 148,000. MRI revealed a 7.2 cm lesion, staged as Pre-Treatment Extent 2 (PRETEXT) in the right anterior liver. She underwent cholecystectomy and right hepatectomy. Resection specimen revealed a mixed neoplasm comprising epithelial components (fetal and embryonal) and mesenchymal components. Additionally, notable findings include small cell component and teratoid features, characterized by melanin pigment and neuroectodermal elements. All the neoplastic cells showed reactivity with CD34, reticulin, SALL4, beta-catenin, GPC-3, arginase-1, chromogranin, and glutamine synthetase. Notably, the teratoid area only displayed positivity for CD56 and NSE, while vimentin highlighted capillaries, vessels and focally staining small cells. Furthermore, CK19 highlighted the small cell components and the bile ducts in the background liver. Importantly, INI-1 staining was retained in all tumor cells, including the small cell component. Synaptophysin and Prussian blue were negative in all lesional cells. After a 2-year follow-up, no recurrence was observed. Results (if a Case Study enter NA) NA Conclusion This case underscores the diagnostic challenge posed by small cell undifferentiated (SCUD) hepatoblastoma. Moreover, it contributes to the understanding of this rare variant of hepatoblastoma and suggests a potential favorable prognosis associated with retained INI-1 staining in the SCUD component.