Malignant Gastrointestinal Neuroectodermal Tumor of Small Intestine Showing DOG1 Expression: A Case Report and Review of Literature.

This article focuses on malignant gastrointestinal neuroectodermal tumor (GNET), a rare and aggressive mesenchymal tumor of the gastrointestinal tract that requires differentiation from other tumors such as gastrointestinal stromal tumor (GIST) due to differences in prognosis and treatment. The report presents a case of GNET in the small intestine exhibiting aberrant DOG1 expression, a marker typically associated with GIST, which complicated diagnosis. Diagnosis was established through a combination of clinical presentation, histomorphology, immunohistochemistry showing positivity for S100, SOX10, and DOG1 but negativity for KIT and melanocytic markers, and molecular analysis confirming EWSR1::ATF1 gene fusion. The article emphasizes the importance of comprehensive diagnostic approaches to distinguish GNET from other tumors with overlapping features and highlights the need for further studies on DOG1 expression in GNET.