Heterotopic pancreas (ectopic pancreas) refers to aberrant pancreatic tissue without anatomical or vascular connection to the normal pancreas. It is most commonly found in the gastric antrum (25-38%), particularly on the greater curvature side in submucosal location. Prevalence ranges from 0.55-13.7% in autopsy series. It typically presents as a 1-3 cm, well-defined, smooth-surfaced submucosal mass with a characteristic central umbilication (rudimentary duct opening) on its surface — considered pathognomonic on endoscopy. On CT, it appears as a submucosal, well-defined, moderately enhancing mass with enhancement pattern similar to normal pancreas. On MRI, T1 and T2 signal characteristics parallel normal pancreatic parenchyma. Most cases are asymptomatic and incidentally discovered, while some may cause epigastric pain, bleeding, or rarely pancreatitis-like complications. Malignant transformation is extremely rare but has been reported.
Age Range
20-70
Peak Age
40
Gender
Male predominant
Prevalence
Uncommon
Heterotopic pancreas results from aberrant tissue implantation during rotation of pancreatic dorsal and ventral buds at the foregut-midgut junction during the 5th-8th weeks of embryonic development. Two embryological mechanisms are proposed: (1) small fragments separating from the pancreatic primordium during rotation becoming embedded in the gastrointestinal wall, (2) endodermal stem cells undergoing pancreatic differentiation at ectopic locations. Heinrich classification defines three histological types: Type I (complete — acini, ducts, and islets), Type II (canalicular — ducts and acini only), Type III (exocrine — duct structures only). Imaging findings depend on histological composition: acinar-rich heterotopic pancreas shows enhancement similar to normal pancreas because the dense capillary network and secretory activity of acinar cells create similar vascular patterns. Central umbilication represents the opening point of the rudimentary pancreatic duct to the gastric mucosa — visible as a central low-density focus on CT or dimple on endoscopy. T1 signal characteristics on MRI derive from the paramagnetic manganese content and proteinaceous secretions of pancreatic acinar cells.
Central low-density focus in the submucosal mass in the gastric antrum or central dimple on endoscopy — represents the opening point of the rudimentary pancreatic duct to the gastric mucosa. This finding is considered pathognomonic for heterotopic pancreas and is the most reliable indicator for differentiation from other gastric submucosal masses.
In CT arterial phase, a well-defined, homogeneous, moderately enhancing mass is observed in the gastric antral submucosa. Enhancement pattern and intensity resemble normal pancreatic parenchyma — suggesting presence of pancreatic acinar tissue. Central low-density focus (rudimentary duct) may be visible.
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A [size] mm well-defined submucosal mass in the gastric antrum demonstrating enhancement pattern similar to normal pancreatic parenchyma is identified, consistent with heterotopic pancreas.
On non-contrast CT, a small low-density focus or depression may be observed in the central area of the lesion — representing the rudimentary pancreatic duct opening. This central umbilication is a highly specific finding for heterotopic pancreas. Overall lesion density is of soft tissue density (30-50 HU).
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A small low-density focus in the central portion of the lesion is observed, consistent with rudimentary duct opening (central umbilication).
On MRI T1-weighted fat-suppressed sequence, heterotopic pancreas shows isointense or mildly hyperintense signal similar to normal pancreas. T1 hyperintense signal results from proteinaceous secretions of pancreatic acinar cells. This signal characteristic helps differentiate from GIST and other submucosal tumors.
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On MRI T1-weighted fat-suppressed sequence, the lesion demonstrates isointense/mildly hyperintense signal similar to normal pancreatic parenchyma.
On T2-weighted sequences, the lesion shows signal similar to or slightly hyperintense compared to normal pancreas. Homogeneous signal pattern reflects uniform pancreatic acinar tissue structure. Fluid content of the central duct may be visible as a focal T2 hyperintense focus.
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On MRI T2-weighted sequence, the lesion shows signal similar to normal pancreas with a focal T2 hyperintense focus in the central duct.
On transabdominal US or EUS, a well-defined, hypoechoic or mixed echogenicity submucosal mass is observed in the gastric antrum. It originates from the muscularis propria or submucosa. A central hyperechoic focus may represent the rudimentary pancreatic duct. Color Doppler shows moderate vascularity.
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On US, a [size] mm well-defined hypoechoic submucosal mass in the gastric antrum is identified with a central hyperechoic focus, suggestive of heterotopic pancreas.
In portal venous phase, heterotopic pancreatic tissue maintains enhancement with intensity paralleling normal pancreatic parenchyma. This persistent enhancement pattern reflects the slow contrast washout kinetics of pancreatic acinar tissue and differs from the more heterogeneous enhancement pattern of GIST.
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In portal venous phase, the lesion maintains enhancement with intensity paralleling normal pancreatic parenchyma.
Criteria
Contains acini, duct structures, and islets of Langerhans — harbors all components of normal pancreatic tissue.
Distinct Features
Type most closely resembling normal pancreas on CT and MRI. Endocrine tumors such as insulinoma or gastrinoma may rarely develop. Enhancement exactly matches normal pancreas.
Criteria
Contains only acini and duct structures — islets of Langerhans are absent.
Distinct Features
Most common type. Exocrine function preserved, and pancreatitis-like complications (ectopic pancreatitis) may develop. Enhancement similar to normal pancreas.
Criteria
Contains only duct structures — acini and islet tissue absent. Also termed adenomyoma.
Distinct Features
Enhancement may be less prominent compared to other types — vascularity decreases in absence of acinar tissue. May appear more hypointense on CT. Malignant transformation reported more frequently in this type.
Distinguishing Feature
GIST usually larger, heterogeneous enhancement, necrosis/cavitation, CD117 positive; heterotopic pancreas small, homogeneous, pancreas-like enhancement, central umbilication
Distinguishing Feature
Carcinoid tumor mucosal/submucosal polypoid lesion, arterial enhancement; heterotopic pancreas submucosal, central umbilication and pancreas-like enhancement profile
Distinguishing Feature
Glomus tumor markedly hypervascular (aorta-like enhancement); heterotopic pancreas shows moderate enhancement paralleling pancreatic parenchyma
Distinguishing Feature
Leiomyoma T1 iso/hypointense, T2 low-intermediate signal; heterotopic pancreas T1 mildly hyperintense (manganese/protein effect), T2 pancreas-like signal and central umbilication
Urgency
routineManagement
conservativeBiopsy
Not NeededFollow-up
12-monthAsymptomatic heterotopic pancreas generally requires no treatment and has low clinical significance. Surgical excision (laparoscopic wedge resection or endoscopic resection) is performed in symptomatic cases (abdominal pain, bleeding, obstruction) or diagnostic uncertainty. Although malignant transformation is extremely rare (0.7-1.8%), adenocarcinoma development has been reported especially in Heinrich Type III. Complications include: ectopic pancreatitis, peptic ulcer (acid secretion), intussusception, and biliary obstruction (in duodenal location). EUS-FNA has limited sensitivity for definitive diagnosis; definitive diagnosis usually requires histopathology on surgical specimen.
Heterotopic pancreas is usually asymptomatic and incidentally detected. Rare complications include pancreatitis, bleeding, and obstruction. Endoscopic/surgical resection is performed for symptomatic or diagnostically uncertain cases.