Epithelioid Gastrointestinal Stromal Tumor of Duodenum Mimicking Adenocarcinoma: A Case Report.

Gastrointestinal stromal tumor is a mesenchymal tumor of gastro-intestinal tract. This epithelioid type gastrointestinal stromal tumor seen in a 22-year-old male with epigastric pain as a presenting symptom had morphological resemblance to carcinoma. However, the immunohistochemistry profile with CD117 and DOG 1 positivity, combined with AE1/AE3 positivity confirmed the tumor as gastrointestinal stromal tumor. Approximately 95% of the patients with gastrointestinal stromal tumor show CD117 immunoreactivity. The treatment approach of CD117 positivity in gastrointestinal stromal tumor has therapeutic benefit with tyrosine kinase inhibitors. Preoperative Imatinib therapy with complete excision can decrease the disease recurrence. Histopathological examination with immunohistochemical studies help to reach the definite diagnosis.