Duodenal gastrointestinal stromal tumor resembling a pancreatic neuroendocrine tumor in a patient with neurofibromatosis type I (von Recklinghausen's disease): a case report

INTRODUCTION Gastrointestinal stromal tumor is the most frequent nonepithelial tumor found in the gastrointestinal tract. One important clinical problem is that gastrointestinal stromal tumors, especially the extramural growth type, can be difficult to distinguish from other organ tumors. The case of a patient with an extramural gastrointestinal stromal tumor of the duodenum that mimicked a pancreatic head tumor has previously been reported. Here, we report a rare case of a patient with a duodenal gastrointestinal stromal tumor with extramural growth that mimicked a pancreatic neuroendocrine tumor. In this case, the gastrointestinal stromal tumor was also associated with neurofibromatosis type 1 (also known as von Recklinghausen's disease). To the best of our knowledge, this is the first report to describe the case of a patient with a duodenal gastrointestinal stromal tumor with neurofibromatosis type 1 in which the radiological findings resembled those of a pancreatic neuroendocrine tumor. CASE PRESENTATION A 60-year-old Japanese woman with a history of neurofibromatosis type 1 was admitted to our hospital for the treatment of a tumor of her pancreas. She had no symptoms, but an abdominal ultrasonography screening examination had revealed a hypoechoic mass in the head of her pancreas. Laboratory data, including tumor markers, were within the normal ranges, and her insulin and glucagon levels were also within the normal ranges. However, her plasma gastrin level was elevated at 580 pg/mL (30 to 150 pg/mL). A computed tomography examination revealed a hypervascular tumor measuring 14 mm in diameter in the head of her pancreas. We diagnosed the patient as having a pancreatic neuroendocrine tumor and performed a tumor resection with a duodenal wedge resection. Microscopic analysis revealed spindle cell tumors in a trabecular pattern. The patient was finally diagnosed as having a duodenal gastrointestinal stromal tumor of the uncommitted type. CONCLUSION Extramural growth-type gastrointestinal stromal tumors can be difficult to distinguish from other organ tumors. In our case, a duodenal gastrointestinal stromal tumor was difficult to distinguish from a pancreatic neuroendocrine tumor based on radiological findings. When patients are identified as having hypervascular lesions that have adhered to the gastrointestinal tract, the possibility of an extramural growth-type gastrointestinal stromal tumor as a differential diagnosis should be considered in patients with neurofibromatosis type 1.