During a medical health check, a 29-year-old man was presented to our hospital with iron deficiency anemia. He had no significant medical history in his family. Despite being diagnosed with ocular sarcoidosis 5 years ago, he had no vision problems. Physical examination revealed normal vital signs and a nontender abdomen;however, his eyelid conjuvitis was pale, and he became aware of fatigue when moving vigorously. He had upper gastrointestinal endoscopy and colonoscopy, but there was no evidence of bleeding detected. A contrasted mass 30mm in size was discovered on abdominal contrast-enhanced computed tomography at the dorsal wall of the proximal jejunum. Positron emission tomography showed an accumulation image in the bilateral hilar lymph and upper jejunum. A 30-mm submucosal tumor with a central depression in the upper jejunum was discovered using a double-balloon enteroscopy. We performed biopsies from the depression margin and tattoo marking on the oral side of the tumor. Even though the biopsies specimen revealed granulation tissue, the patient was referred to surgery and underwent a partial jejunum resection because the tumor was diagnosed as the cause of anemia. The operation went smoothly, and the patient was discharged on the seventh postoperative day. Histological examination showed a proliferation of densely packed spindle cells with prominent nuclear palisading. The immunohistochemical examination revealed that c-kit and CD34 were highly expressed, whereas desmin and S-100 proteins were not. Ki-67 expression demonstrated a very low proliferative index (2%). We discovered gastrointestinal stromal tumors (GIST), as well as an ectopic pancreas. GIST is extremely rare in young people, and the coexistence of ectopic pancreas and sarcoidosis has never been reported.