In the field of oncology, cancer is usually detected in 1 of 2 ways: incidentally or via a screening program. In some cancers, such as duodenal gastrointestinal stromal tumor (GIST), surgeons may experience difficulty in pinpointing its exact location, especially if the tumor growth is extraluminal and extends to the head of the pancreas. 

GIST is an extremely rare cancer, despite its being the most common mesenchymal malignancy arising from the gastrointestinal tract. GISTs rarely occur in the duodenum; only an estimated 3%-5% of cases involve that anatomical area. In contrast, the most common site of occurrence is the stomach (50%-60%), followed by the small intestine (20%-30%). 

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“[Duodenal GISTs] may develop extramurally, extensively, in a stem-like fashion, or may be embedded in the pancreatic parenchyma, complicating the distinction from duodenal or pancreatic primary hypervascularized enhancing tumors on computed tomography (CT) and the selection of the appropriate surgical technique,” Inoue and colleagues wrote in the Journal of Medical Case Reports. 

It is important to note that both duodenal GISTs and pancreatic neuroendocrine tumors appear similar in imaging studies, and the 2 lesions are commonly misdiagnosed. A literature review on both types of lesions indicates that surgeons struggle with differentiating the 2 preoperatively. Fortunately, endoscopic ultrasound-guided fine needle aspiration can greatly aid surgeons in correctly diagnosing the lesion, and it is the only way to obtain a preoperative pathological diagnosis. 

Statistically, endoscopic ultrasound-guided fine needle aspiration has a specificity of 100% and a sensitivity of 84%. However, surgeons should be aware that adverse events related to this procedure do occur, albeit rarely (less than 4% of the time). Mistakes can be extremely costly, leading to acute pancreatitis, duodenal perforation, bleeding, and infection. 

Case Study: Anemia Caused by Gastrointestinal GIST 

Inoue and colleagues presented the case study of a 44-year-old female who was identified to have anemia from a workplace medical examination. Six months later, she presented to the hospital with complaints of lightheadedness; her hemoglobin levels at that time were found to be extremely low (4.1 g/dL). Other laboratory findings were in the normal range. She was duly prescribed blood transfusions and ferrotherapy. 

With such low hemoglobin, physicians needed to rule out any source of bleeding. A physical and neurological examination was normal. A contrast-enhanced computed tomography (CT) scan revealed a 30 mm mass that was heterogeneously enhanced at the margins. Nevertheless, physicians were unable to differentiate whether the tumor originated at the duodenum or the head of the pancreas. 

A detailed history from the patient revealed that her father died of pancreatic cancer. She has no other relevant medical history; she never smoked and does not drink alcohol. 

Other tests were performed. An upper gastrointestinal endoscopy revealed bulging with redness and erosion in part of the duodenal bump. A mucosal biopsy was obtained, but it failed to be diagnostic. 

Her surgeons attempted to perform an endoscopic ultrasound-guided fine needle aspiration, but the procedure was hampered by a pulsating blood vessel present in the region to be punctured. These findings led her physicians to diagnose a pancreatic neuroendocrine tumor that extended to the duodenum. 

A pancreaticoduodenectomy was performed. The surgeons retrieved a 3.0 x 2.3 x 3.9 cm3 mass that occupied the first part of the duodenum. The mass broke down on the mucosal surface to form an ulcer, and the lesion extended towards the pancreatic head. 

“The tumor was diagnosed as a high-risk [duodenal GIST] on the basis of the Fletcher classification or modified Fletcher classification,” Inoue et  al wrote. “The patient was treated with adjuvant imatinib, and she has not developed a recurrence over a 2-year period.” 

The Efficacy of Surgical Resection 

In the case of this patient, her duodenal GIST was likely the cause of her anemia, considering that the most common sign of a duodenal GIST is bleeding. 

There is a lack of consensus on the best way to surgically treat duodenal GISTs. The main contenders are either pancreaticoduodenectomy or local resection. There have been a number of studies exploring the merits of both surgical options, but they were mostly limited by small study populations (as is often the case when investigating rare diseases). 

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Some studies advocate for pancreaticoduodenectomy as the surgery of choice for the removal of duodenal GISTs; others associate this procedure with an inferior oncological outcome. In Asian Journal of Surgery, Zhou and colleagues argue that the outcomes of pancreaticoduodenectomy have much to do with other adverse biological factors that have nothing to do with the merits of this surgical operation. 

“Therefore, the choice of the surgical approach should depend on the anatomical location and tumor size,” they wrote. 

Nevertheless, sufficient evidence in medical literature supports the view that surgical resection improves the prognosis of patients with duodenal ulcers. Regardless of the choice of surgical resection, it seems clear that any attempt to remove the lesion is better than leaving it as it is, even when potential adverse events are taken into account. 


Zhou Y, Wang X, Si X, Wang S, Cai Z. Surgery for duodenal gastrointestinal stromal tumor: a systematic review and meta-analysis of pancreaticoduodenectomy versus local resectionAsian J Surg. Published online December 31, 2019. doi:10.1016/j.asjsur.2019.02.006

Harris PS, Romano J, Russ KB, Shoreibah MG, Baig KRKK. Gastrointestinal stromal tumor: GIST, another duodenal ulcerOchsner J. Published online June 23, 2020. doi:10.31486/toj.18.0167

Inoue M, Ohmori I, Watanabe A, et al. A duodenal gastrointestinal stromal tumor mimicking a pancreatic neuroendocrine tumor: a case reportJ Med Case Rep. Published online August 16, 2022. doi:10.1186/s13256-022-03468-7