Malignant Gastrointestinal Neuroectodermal Tumor: a case report and a review of the literature

Introduction/Objective Malignant gastrointestinal neuroectodermal tumor (GNET) is a rare soft tissue tumor arising in the wall of the gastrointestinal tract. The GNET was first described as an osteoclast rich tumor of the gastrointestinal tract with features resembling clear cell sarcoma, with only few cases reported in the literature. Methods/Case Report We report a case of a 71-year-old man with a past medical history of hypertension, hyperlipidemia, and benign prostatic hyperplasia presented with complaints of dyspnea, dizziness, fatigue, black stools, and a recent syncopal episode. Laboratory testing revealed anemia (HB 5.4 g/dL). Esophagogastroduodenoscopy demonstrated a submucosal gastric mass. An abdominal CT scan confirmed a 7.8 cm mass along the gastric cardia and fundus. Results (if a Case Study enter NA) Biopsy rendered a gastrointestinal neuroectodermal tumor (GNET). Microscopically, the tumor cells were spindle with eosinophilic cytoplasm and arranged in fascicules. They were positive for CD56, CD99, and Fli-1, synaptophysin, and negative for chromogranin, TTF-1, SMA, desmin, CD34, EMA, pan-cytokeratin, and lymphoid markers. Two months later, further imaging confirmed metastasis to the liver and spleen. GNETs typically arise within the muscularis propria of the gastrointestinal tract and often extend into the submucosa and subserosa. Conclusion The most important differential of GNET is the clear cell sarcoma of the gastrointestinal tract (CCS-GI). Both share similar morphological as well as molecular features and show S100 positivity; however, the lack of melanocytic differentiation in GNET distinguishes it from CCS-GI. Both typically show rearrangements of the EWSR1 gene, with t(12;22) (q13;q12) EWSR1-ATF1 or t(2;22)(q34;q12) EWSR1-CREB1 fusions. Pathologists should be aware of GNET diagnostic entity due to its aggressive behavior and high rate of recurrence and mortality even after complete resection.