Miller, C. QuinnAl-Hader, AhmadVance, Gail H.Zhang, Chen2024-09-162024-09-162022-07-20Miller CQ, Al-Hader A, Vance GH, Zhang C. Malignant gastrointestinal neuroectodermal tumour arising in the extrahepatic bile ducts; a rare neoplasm in an unusual anatomic location. BMJ Case Rep. 2022;15(7):e250094. Published 2022 Jul 20. doi:10.1136/bcr-2022-250094https://hdl.handle.net/1805/43316Malignant gastrointestinal neuroectodermal tumour (GNET) is a rare, aggressive neoplasm with fewer than 100 cases reported in the literature. Most cases arise in the tubular gastrointestinal tract. We reported a unique case of GNET arising in the extrahepatic bile ducts and reviewed the literature of GNETs. The patient is a female in her mid-30s who presented with painless jaundice and diarrhoea several months after cholecystectomy for biliary dyskinesia. Workup revealed a tumour arising from the peripheral 4B bile ducts involving the left hepatic duct and bifurcation. Histologic examination of the lesion showed a malignant spindled and epithelioid neoplasm which strongly expressed S100 and SOX-10. Neoplastic cells were negative for various cytokeratins and melanoma markers. FISH testing using EWSR1 break-apart probes showed rearrangement of the EWSR1 gene region. The immunohistochemical and molecular findings are consistent with a diagnosis of GNET arising in the extrahepatic bile ducts.en-USPublisher PolicyHepatic cancerPathologyCholecystectomyArticle