Gastric Spindle Cell Neuroendocrine Tumor Mimicking Gastrointestinal Stromal Tumor: Unique Morphology and Diagnostic Pitfall

Gastric neuroendocrine tumors (GNETs) with spindle cell morphology are extremely rare. We present a case of a 49-year-old female patient with a history of systemic lupus erythematosus, Sjogren's syndrome, and gastroesophageal reflux disease. She was initially thought to have a spindle cell gastrointestinal stromal tumor per histological studies of the fundic polypectomy samples. Immunohistochemically, the tumor cells were negative for CD117, and CD34, but positive for chromogranin, synaptophysin, and CD56 with a 6% Ki-67 index, consistent with a spindle cell-type well differentiated neuroendocrine tumor, World Health Organization (WHO) Grade 2. To the best of our knowledge, this is the first case report of a gastric spindle cell neuroendocrine tumor in the English literature.