Malignant Gastrointestinal Neuroectodermal Tumor, a Rare Neoplasm, Presenting With Hemoperitoneum and Malena: A Case Report.

Malignant gastrointestinal neuroectodermal tumor (GNET) are rare malignant mesenchymal tumors. The tumor can present with various symptoms like abdominal pain, anorexia, or small bowel obstruction. Here, we present a case of small intestinal GNET who presented with gastrointestinal bleed and hemoperitoneum, a rare presentation of this disease. This patient was misdiagnosed initially as Crohn's disease and treated for the same. However, non-response to the standard treatment and onset of new symptoms like malena and ascites raised the suspicion of some alternate diagnosis. Exploratory laparotomy showed the presence of hemoperitoneum along with a mass, 100 cm proximal to ileo-cecal junction. She was successfully treated with surgical resection and anastomosis. Histopathology, immunohistochemistry (diffuse positivity for S100 and weak positivity for synaptophysin) and molecular fluorescence in-situ hybridization (FISH) study (translocation involving the chromosomal region 2212.1-q12.2 which harbors EWSR1 gene) confirmed the diagnosis of GNET.