부산대학교 도서관

Wenfeng Xu, Hao Tang, Ying Chen, Jiashuang Wang, Zhongjiao Chen, Yujuan Xu, Deyu Guo Department of Pathology, Guiqian International General Hospital, Guiyang City, Guizhou Province, People’s Republic of ChinaCorrespondence: Deyu Guo, Email 2580685422@qq.comBackground: Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract with a broad morphological spectrum. Although epithelioid GISTs account for 20% of GISTs, their morphological features may pose a diagnostic pitfall for pathologists due to their morphological similarities to poorly differentiated adenocarcinoma and lymphoma.Case Presentation: Herein, we report a 65-year-old male patient with gastric epithelioid GIST misdiagnosed as adenocarcinoma for four years. During this period, he was treated with chemotherapy combined with PD-L1 immunotherapy. The clinicians thought the treatments were effective. However, there was no significant change in tumor size. The patient’s clinical symptoms did not improve significantly as well. Finally, an endoscopic biopsy was performed again and gastric epithelioid GIST was confirmed in our hospital through morphology, immunohistochemistry, and whole-genome sequencing.Conclusion: A broad morphological spectrum and diverse immunophenotypic changes of GISTs could represent a pitfall for pathologists. However, predisposed anatomical sites, morphology, and corresponding immunohistochemical markers are of great significance for the diagnosis of GISTs and the differential diagnosis from other diseases. On the other hand, clinicians should diagnose and comprehensively evaluate treatment effects based on the patient’s clinical symptoms and relevant laboratory examinations, instead of over-reliance on pathological diagnosis.Keywords: gastrointestinal stromal tumors, misdiagnosis, poorly differentiated adenocarcinoma, stomach