Duodenal gastrointestinal stromal tumour imitating as pancreatic head tumour.

Duodenal gastrointestinal stromal tumours (D-GISTs) are a rare disease. It may arise commonly from the second or third part of the duodenum and can be erroneously diagnosed as a pancreatic head tumour due to proximity and morphology on imaging studies. We present a case of a 60-year-old woman who presented with abdominal pain and was diagnosed as a case of pancreatic neuroendocrine tumour on radiologic imaging and granulomatous lesion on aspiration cytology. A ~5×3 cm mass was noted in the pancreatic head on laparotomy, and pancreatoduodenectomy was performed. Histopathology reported an exophytic GIST arising from the second part of the duodenum. Hence, D-GIST can invade the pancreas and mimic pancreatic head tumours; therefore, these tumours should be kept in the differential diagnosis of an atypical pancreatic head mass.