“Heterotopic pancreas is an entity in which pancreatic elements are found outside of the gland proper. In the literature, it is defined as elements without anatomic or vascular connection to the gland. It is overall a relatively uncommon entity with a reported incidence of 0.5%–14% in autopsy series . The true incidence is unknown as most cases are asymptomatic.”
Heterotopic pancreatic rests: imaging features, complications, and unifying concepts
Kim DU, Lubner MG, MellnicknV.M. et al.
Abdom Radiol (2016). doi:10.1007/s00261-016-0874-9

“The stomach and duodenum have been variably described as the most common sites of involvement with reported frequencies of 24%–38% and 9%–36%, respectively. Gastric lesions are typically located in the antrum, along the greater curvature, within 3–6 cm of the pylorus, while duodenal lesions are located in the proximal portions. Both gastric and duodenal lesions are typically round or ovoid and located in the submucosa with an endophytic growth pattern. Occasionally, heterotopic pancreatic elements have been found in the muscularis propria or serosa.”
Heterotopic pancreatic rests: imaging features, complications, and unifying concepts
Kim DU, Lubner MG, MellnicknV.M. et al.
Abdom Radiol (2016). doi:10.1007/s00261-016-0874-9

“Most cases of pancreatic heterotopia are asymptomatic and incidentally discovered. The symptomatic cases are most commonly encountered in 40–50 year old males. The most common symptom is upper abdominal pain with less common symptoms, including nausea, vomiting, weight loss, and jaundice . Symptoms are postulated to be secondary to complications of pancreatic heterotopia, which can be broadly divided into two categories—those possible in any mass, largely determined by location, and those specific to pancreatic tissue.”
Heterotopic pancreatic rests: imaging features, complications, and unifying concepts
Kim DU, Lubner MG, MellnicknV.M. et al.
Abdom Radiol (2016). doi:10.1007/s00261-016-0874-9