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Heterotopic pancreas: typical and atypical imaging findings
Clinical Radiology 65 (2010) 403–407
Contents lists available at ScienceDirect
Clinical Radiology journal homepage: www.elsevierhealth.com/journals/crad
Pictorial Review
Heterotopic pancreas: typical and atypical imaging findings J.W. Kung a, *, A. Brown b, J.B. Kruskal a, J.D. Goldsmith c, I. Pedrosa a a
Department of Radiology, Beth Israel Deaconess Medical Center, 330 Brookline Ave, Boston, MA 02215, USA Department of Gastroenterology, Beth Israel Deaconess Medical Center, 330 Brookline Ave, Boston, MA 02215, USA c Department of Pathology, Beth Israel Deaconess Medical Center, 330 Brookline Ave, Boston, MA 02215, USA b
art icl e i nformat ion Article history: Received 26 September 2009 Received in revised form 6 January 2010 Accepted 8 January 2010
Heterotopic pancreas is a common condition often encountered during laporotomy or autopsy. Prospective radiographic diagnosis is challenging because of the variable imaging appearances. The purpose of this review is to present the typical and atypical appearances of heterotopic pancreas on imaging studies. Familiarity with the spectrum of radiological findings in conjunction with biochemical markers is helpful to improve diagnostic accuracy. Ó 2010 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.
Introduction Heterotopic pancreas represents a congenital anomaly where aberrant pancreatic tissue is without ductal or vascular continuity to the gland.1 The reported incidence ranges from 0.55–13.7%,1,2 however, the true incidence is unknown as most patients are asymptomatic and the condition is usually an incidental finding at autopsy or laparotomy. Most ectopic pancreatic tissue is found incidentally during evaluation of other organs.3 Common sites of involvement include the upper portions of the gastrointestinal tract including the stomach, duodenum, and proximal jejunum. Additional sites include the ileum, Meckel’s diverticulum, common bile duct, umbilicus, gallbladder, spleen, fallopian tubes, and mediastinum.1,4–6 It is usually found in the submucosal layer, but has also been found in the muscularis and serosal layers.7 The factors leading to the development of ectopic pancreatic tissue remain unknown. However, in some
* Guarantor and correspondent: Department of Radiology, Beth Israel Deaconess Medical Center, 330 Brookline Ave. Boston, MA 02215, USA. Tel.: þ1 267 979 8600; fax: þ1 617 667 7917. E-mail address: [email protected] (J.W. Kung).
transgenic animals in which the Cdx2 homeobox is absent there appears to be a significant increase of ectopic pancreas found. This indicates that the Cdx2 homeobox may be critical to the expression of ectopic pancreatic tissue. Additional work in chickens indicates that inhibition of signalling for Sonic Hedge Hog (Shh) results in the formation of ectopic pancreatic tissue.8 It remains unknown whether these mutations are active in human cases of ectopic pancreatic tissue production. Heterotopic pancreas undergoes changes similar to the native pancreatic gland and symptoms often depend upon location. Changes to the ectopic tissue can include chronic inflammation, fibrosis, and even the development of pancreatic adenocarcinoma.9,10 Reported symptoms include epigastric pain and weight loss,11 bowel obstruction,5,12 and bleeding.1 Pseudocyst formation, pancreatitis, and malignant transformation have also been documented.5,13,14 However, most individuals remain asymptomatic clinically and are detected during surgery or endoscopy for another evaluation. When symptoms do occur the majority are related to a combination of mass effect and the local and systemic complications of activated pancreatic enzymes.15 Other possible presentations include obstruction from duodenal or pyloric stricture, gastrointestinal haemorrhage, or elevation in serum amylase and lipase.
0009-9260/$ – see front matter Ó 2010 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.crad.2010.01.005
404
J.W. Kung et al. / Clinical Radiology 65 (2010) 403–407
the stomach, as well as atypical locations, and atypical presentations.
Upper gastrointestinal tract
Figure 1 An 18-year-old woman with symptomatic heterotopic pancreas. Single-contrast upper gastrointestinal fluoroscopic image demonstrates an intramural lesion (black arrow) along the greater curvature of the gastric antrum. Notice central pooling of contrast agent suggestive of pancreatic duct.
Diagnosis of ectopic pancreas can be achieved radiographically but usually the definitive diagnosis is made during surgical or endoscopic evaluation. Imaging findings may be seen on upper gastrointestinal series (UGI), ultrasound (including endoscopic), computed tomography (CT), and magnetic resonance imaging (MRI). Features are frequently nonspecific. The mass is typically situated in the submucosa, but sometimes extends into the muscular wall resembling leiomyoma or other submucosal tumours.16,17 Diagnosis is difficult prospectively16 and is often made after biopsy or resection.14 In this article, we review the radiographic findings of heterotopic pancreas including the typical appearance in
Heterotopic pancreas is most often incidentally discovered in the upper gastrointestinal tract, with the stomach being the most common location.1 Lesions in the stomach range from 1–3 cm and are usually located along the greater curvature in the gastric antrum within 6 cm of the pylorus.1,12,18 The radiographic findings of heterotopic pancreas on UGI series are well described.12,18 The mass has a broad base and smooth surface characteristic of extra-mucosal intramural tumours. Occasionally, the lesion can appear sessile, with a narrow base and is mistaken for a gastric polyp. Umbilication manifested by pooling of barium is thought to represent the ductal remnant. Visualization of a bariumfilled pit at the centre of the lesion permits the specific diagnosis of heterotopic pancreatic tissue (Fig. 1).18 Larger umbilications present a diagnostic dilemma and are often mistaken for gastric ulcers or ulcerating intramural tumours. On ultrasound/endoscopic ultrasound heterotopic pancreas often appears as a solid submucosal mass (Fig. 2b–c) of low echogenicity, compared to the hyperechoic submucosa, and isoechoic to the hypoechoic muscularis propria layer.19,20 At CT a prospective diagnosis of heterotopic pancreas is challenging. Masses are often oval or round with smooth or serrated margins in the gastric antral wall16 (Fig. 3). Often there is homogeneous early enhancement, similar to the normal pancreas. Occasionally, poor enhancement is seen, in which case lesions have been shown to consist primarily of ducts and hypertrophied muscle.17 A minority of cases show dilatation of heterotopic pancreatic duct. Water has been proposed as an oral contrast agent due to improved depiction of the submucosal location of the heterotopic pancreas during the portal phase or non-equilibrium phase of scanning, although it has not been demonstrated to improve the preoperative diagnostic rate.16
Figure 2 A 49-year-old man with epigastric pain and heterotopic pancreas in the stomach. (a) Coronal, T2-weighted image demonstrating a smoothly marginated submucosal lesion of high signal intensity on T2-weighted imaging (white arrow). Note the dilated ectopic pancreatic duct. (b) Endoscopy demonstrating a 1–2 cm submucosal lesion in the proximal antrum. (c) Endoscopic ultrasound was performed using a radial echoendoscope at 7.5 MHz. A hypoechoic homogeneous antral mass (black arrowheads) is consistent with a heterotopic pancreatic rest.
J.W. Kung et al. / Clinical Radiology 65 (2010) 403–407
405
Figure 3 A 61-year-old man with asymptomatic heterotopic pancreas. Contrast-enhanced CT image acquired in the portal venous phase demonstrates a submucosal mass (black arrow) of homogeneous attenuation similar to the pancreatic parenchyma, along the greater curvature of the gastric antrum.
MRI findings of heterotopic pancreas in the stomach have not been well described. The signal characteristics and enhancement of heterotopic pancreas should parallel those of the native pancreatic gland. However, intense enhancement greater than that of normal pancreas may be seen (Fig. 4). The normal pancreatic parenchyma typically exhibits a signal intensity similar to (in older patients) or higher than (younger patients) the normal liver parenchyma on T1-weighted images21 (Fig. 4b). MR cholangiopancreatography (MRCP) is usually performed with heavily T2-weighted images. Evaluation with MRCP or typical T2-weighted sequences may allow identification of the ‘‘ectopic duct sign,’’ a dilated ectopic pancreatic duct (Fig. 2a). In these cases, the mass demonstrates predominantly high signal intensity on the T2-weighted images. The use of secretin during the MRCP examination may improve the visualization of the ductal system in the heterotopic pancreas.
Figure 5 A 41-year-old woman with heterotopic pancreas in the oesophagus. Double contrast barium oesophagram demonstrating a broad-based submucosal lesion (white arrows). Note the obtuse angles between the mass and mucosa indicating the submucosal location.
Atypical locations of heterotopic pancreas Atypical locations of heterotopic pancreas include the ileum, Meckel’s diverticulum, common bile duct, umbilicus, gallbladder, omentum, spleen, mediastinum, and fallopian
Figure 4 A 61-year-old man with asymptomatic heterotopic pancreas (same patient as Fig. 3). (a) Axial, three-dimensional, fat-saturated, T1-weighted, spoiled-gradient echo image of the upper abdomen shows a heterogeneous submucosal lesion (white arrow) along the greater curvature of the antrum. (b) Axial, three-dimensional, fat-saturated, T1-weighted, spoiled-gradient, echo image of the upper abdomen acquired during the portal venous phase demonstrates avid enhancement of greater curvature mass (white arrow). Note the normal pancreas.
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J.W. Kung et al. / Clinical Radiology 65 (2010) 403–407
Figure 6 A 22-year-old woman with heterotopic pancreatitis. (a) Coronal, contrast-enhanced CT image demonstrates enhancing nodular mass (black arrow) abutting a loop of small bowel with inflammatory change in the mesentery (white arrows). Note the normal appearance of the pancreas. (b) Axial, three-dimensional, fat-saturated, T1-weighted, spoiled gradient echo image of the upper abdomen in the same patient demonstrates the nodular lesion (white arrow), now in the left upper quadrant with associated inflammation (arrowheads). (c) Axial, threedimensional, fat-saturated, T1-weighted, spoiled gradient echo image demonstrating normal appearance of the pancreas (white arrows). Note the similar appearance of the mass and the normal pancreas, which exhibits bright signal intensity. (d) Axial, three-dimensional, T2-weighted MRI image demonstrates nonspecific inflammation within the left upper quadrant (white arrowheads). A small fluid collection (white arrow) is noted in the centre. (e) MR cholangiopancreatogram demonstrates inflammation in the left upper (small white arrow) and right lower (large white arrow) quadrants. The common bile duct and pancreatic duct (white arrowheads) are well visualized. At surgery a mobile mass in the jejunal mesentery was found. Pathological evaluation revealed ectopic pancreas with mesenteric inflammation secondary to pancreatitis.
tubes.1,4–6 Heterotopic pancreas in the oesophagus is rare and primarily described in the surgical and gastroenterology literature.19 On barium oesophagram, the lesion presents as a broad based submucosal mass (Fig. 5). Findings on CT and MRI are equally nonspecific.
Atypical presentations of heterotopic pancreas Many patients with heterotopic pancreas are presumably asymptomatic and most heterotopic pancreas goes
Figure 7 A 46-year-old man with heterotopic gastric pancreas and cystic pancreatic ductal dilatation. (a) Unenhanced axial CT image demonstrates a solid and cystic mass (white arrow), arising from the greater curvature of the stomach with coarse calcifications (black arrowhead) suggestive of chronic pancreatitis. (b) Axial, contrast-enhanced CT image acquired in the portal venous phase demonstrates a nodular and solid (white arrow) component to the mass. Notice that the solid component has enhancement characteristics similar to the normal pancreatic gland (black arrowheads). (c) Enhanced, coronal CT image demonstrating the predominantly multiloculated cystic nature of the mass (asterisks).
J.W. Kung et al. / Clinical Radiology 65 (2010) 403–407
undetected until incidentally detected at surgery or at autopsy. However, heterotopic pancreas can undergo inflammatory changes (i.e., pancreatitis) similar to the normal pancreatic gland. Inflamed heterotopic pancreas in the mesentery or jejunal wall has been reported 14,16 and mistaken for jejunitis or jejunal tumour. Findings on CT are nonspecific and reveal an ovoid soft-tissue mass in the small-bowel mesentery or jejunum with surrounding mesenteric oedema and thickening of the jejunal wall 13,14 (Fig. 6). The presence of a soft-tissue mass in the epicentre of the inflammatory changes with increased signal intensity on unenhanced T1-weighted images relative to the liver, similar to that of the normal pancreas, may be the key for the diagnosis. MRCP can be used to confirm the presence of a duct within the mass and allow conservative treatment.13 In the face of clinical findings suggestive of pancreatitis, including elevated serum concentrations of lipase and amylase with a normal looking pancreas, this diagnosis should be considered. Heterotopic pancreas can undergo cystic degeneration including cystic dystrophy, often in the duodenum and stomach.22 Evidence of chronic pancreatitis with associated pseudocyst or ectopic ductal dilation can best be seen using CT (Fig. 7). Strategically located heterotopic pancreatic tissue can result in symptoms of obstruction. Heterotopic pancreas at the gastro-oesophageal junction or gastric antrum has resulted in dysphagia19 and gastric obstruction.12 Presentation at the ampulla of Vater can lead to obstructive jaundice.23 Intussusceptions in which the lead point was a mass of heterotopic pancreas have been reported.5 Reports of malignant transformation are extremely rare.24 Heterotopic pancreas undergoes malignant transformation similar to the native gland. Adenocarcinoma, intraductal papillary mucinous neoplasm, and malignant insulinoma have been reported arising in heterotopic pancreatic tissue.5,24,25 The imaging findings are usually nonspecific and diagnosis is often made following surgical resection. In conclusion, we present a spectrum of fluoroscopic and cross-sectional imaging appearances of heterotopic pancreatic tissue that may help suggest the correct diagnosis preoperatively and guide clinical management.
References 1. Dolan RV, ReMine WH, Dockerty MB. The fate of heterotopic pancreatic tissue. A study of 212 cases. Arch Surg 1974;109:762–5.
407
2. Feldman M, Weinberg T. Aberrant pancreas: a cause of duodenal syndrome. JAMA 1952;148:893–8. 3. Prasad TR, Gupta SD, Bhatnagar V. Ectopic pancreas associated with a choledochal cyst and extrahepatic biliary atresia. Pediatr Surg Int 2001;17:552–4. 4. Wang W, Li K, Qin W, et al. Ectopic pancreas in mediastinum: report of 2 cases and review of the literature. J Thoracic Imaging 2007;22:256–8. 5. Barbosa J, Dockerty MB, Waugh JM. Pancreatic heterotopia: review of the literature and report of 41 authenticated surgical cases of which 25 were clinically significant. Surg Gynecol Obstet 1946;82:527–42. 6. Ormarsson OT, Gudmundsdottir I, Marvik R. Diagnosis and treatment of gastric heterotopic pancreas. World J Surg 2006;30:1682–9. 7. Rizzo RJ, Szucs RA, Turner MA. Congenital abnormalities of the pancreas and biliary tree in adults. RadioGraphics 1995;15:49–68. quiz 147–8. 8. Chawengsaksophak K, James R, Hammond VE, et al. Homeosis and intestinal tumours in CdX2 mutant mice. Nature 1997;386:84–7. 9. Rubesin SE, Furth EE, Birnbaum BA, et al. Ectopic pancreatitis complicated by pancreatitis and pseudocyst formation mimicking jejunal diverticulitis. Br J Radiol 1997;70:311–3. 10. Emerson L, Layfield LJ, Rohr LR, et al. Adenocarcinoma arising in association with gastric heterotopic pancreas: a case report and review of the literature. J Surg Oncol 2004;87:53–7. 11. Lai EC, Tompkins RK. Heterotopic pancreas. Review of a 26 year experience. Am J Surg 1986;151:697–700. 12. Thoeni RF, Gedgaudas KR. Ectopic pancreas: usual and unusual features. Gastrointest Radiol 1980;5:37–42. 13. Silva AC, Charles JC, Kimery BD, et al. MR cholangiopancreatography in the detection of symptomatic ectopic pancreatitis in the small-bowel mesentery. AJR Am J Roentgenol 2006;187:W195–W197. 14. Sandrasegaran K, Maglinte DD, Cummings OW. Heterotopic pancreas: presentation as jejunal tumor. AJR Am J Roentgenol 2006;187:W607–W609. 15. Hayes-Jordan A, Idowu O, Cohen R. Ectopic pancreas as the cause of gastric outlet obstruction in a newborn. Pediatr Radiol 1998;28:868–70. 16. Cho JS, Shin KS, Kwon ST, et al. Heterotopic pancreas in the stomach: CT findings. Radiology 2000;217:139–44. 17. Park SH, Han JK, Choi BI, et al. Heterotopic pancreas of the stomach: CT findings correlated with pathologic findings in six patients. Abdom Imaging 2000;25:119–23. 18. Kilman WJ, Berk RN. The spectrum of radiographic features of aberrant pancreatic rests involving the stomach. Radiology 1977;123:291–6. 19. Shalaby M, Kochman ML, Lichtenstein GR. Heterotopic pancreas presenting as dysphagia. Am J Gastroenterol 2002;97:1046–9. 20. Zinkiewicz K, Juskiewicz W, Zgodzinski W, et al. Ectopic pancreas: endoscopic, ultrasound, and radiologic features. Folia Morphol 2003;62: 205–9. 21. Winston CB, Mitchell DG, Outwater EK, et al. Pancreatic signal intensity on T1-weighted fat saturation MR images: clinical correlation. J Magn Reson Imaging 1995;5:267–71. 22. Lopez-Pelaez MS, Hoyos FB, Isidro MG, et al. Cystic dystrophy of heterotopic pancreas in stomach: radiologic and pathologic correlation. Abdom Imaging 2008;33:391–4. 23. Hsu SD, Chan DC, Hsieh HF. Ectopic pancreas presenting as ampulla of Vater tumor. Am J Surg 2008;195:498–500. 24. Ura H, Denno R, Hirata K, et al. Carcinoma arising from ectopic pancreas in the stomach: endosonographic detection of malignant change. J Clin Ultrasound 1998;26:265–8. 25. Phillips J, Katz A, Zoposky P. Intraductal papillary mucinous neoplasm in an ectopic pancreas located in the gastric wall. Gastrointest Endosc 2006;64:814–5.
Contents lists available at ScienceDirect
Clinical Radiology journal homepage: www.elsevierhealth.com/journals/crad
Pictorial Review
Heterotopic pancreas: typical and atypical imaging findings J.W. Kung a, *, A. Brown b, J.B. Kruskal a, J.D. Goldsmith c, I. Pedrosa a a
Department of Radiology, Beth Israel Deaconess Medical Center, 330 Brookline Ave, Boston, MA 02215, USA Department of Gastroenterology, Beth Israel Deaconess Medical Center, 330 Brookline Ave, Boston, MA 02215, USA c Department of Pathology, Beth Israel Deaconess Medical Center, 330 Brookline Ave, Boston, MA 02215, USA b
art icl e i nformat ion Article history: Received 26 September 2009 Received in revised form 6 January 2010 Accepted 8 January 2010
Heterotopic pancreas is a common condition often encountered during laporotomy or autopsy. Prospective radiographic diagnosis is challenging because of the variable imaging appearances. The purpose of this review is to present the typical and atypical appearances of heterotopic pancreas on imaging studies. Familiarity with the spectrum of radiological findings in conjunction with biochemical markers is helpful to improve diagnostic accuracy. Ó 2010 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.
Introduction Heterotopic pancreas represents a congenital anomaly where aberrant pancreatic tissue is without ductal or vascular continuity to the gland.1 The reported incidence ranges from 0.55–13.7%,1,2 however, the true incidence is unknown as most patients are asymptomatic and the condition is usually an incidental finding at autopsy or laparotomy. Most ectopic pancreatic tissue is found incidentally during evaluation of other organs.3 Common sites of involvement include the upper portions of the gastrointestinal tract including the stomach, duodenum, and proximal jejunum. Additional sites include the ileum, Meckel’s diverticulum, common bile duct, umbilicus, gallbladder, spleen, fallopian tubes, and mediastinum.1,4–6 It is usually found in the submucosal layer, but has also been found in the muscularis and serosal layers.7 The factors leading to the development of ectopic pancreatic tissue remain unknown. However, in some
* Guarantor and correspondent: Department of Radiology, Beth Israel Deaconess Medical Center, 330 Brookline Ave. Boston, MA 02215, USA. Tel.: þ1 267 979 8600; fax: þ1 617 667 7917. E-mail address: [email protected] (J.W. Kung).
transgenic animals in which the Cdx2 homeobox is absent there appears to be a significant increase of ectopic pancreas found. This indicates that the Cdx2 homeobox may be critical to the expression of ectopic pancreatic tissue. Additional work in chickens indicates that inhibition of signalling for Sonic Hedge Hog (Shh) results in the formation of ectopic pancreatic tissue.8 It remains unknown whether these mutations are active in human cases of ectopic pancreatic tissue production. Heterotopic pancreas undergoes changes similar to the native pancreatic gland and symptoms often depend upon location. Changes to the ectopic tissue can include chronic inflammation, fibrosis, and even the development of pancreatic adenocarcinoma.9,10 Reported symptoms include epigastric pain and weight loss,11 bowel obstruction,5,12 and bleeding.1 Pseudocyst formation, pancreatitis, and malignant transformation have also been documented.5,13,14 However, most individuals remain asymptomatic clinically and are detected during surgery or endoscopy for another evaluation. When symptoms do occur the majority are related to a combination of mass effect and the local and systemic complications of activated pancreatic enzymes.15 Other possible presentations include obstruction from duodenal or pyloric stricture, gastrointestinal haemorrhage, or elevation in serum amylase and lipase.
0009-9260/$ – see front matter Ó 2010 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.crad.2010.01.005
404
J.W. Kung et al. / Clinical Radiology 65 (2010) 403–407
the stomach, as well as atypical locations, and atypical presentations.
Upper gastrointestinal tract
Figure 1 An 18-year-old woman with symptomatic heterotopic pancreas. Single-contrast upper gastrointestinal fluoroscopic image demonstrates an intramural lesion (black arrow) along the greater curvature of the gastric antrum. Notice central pooling of contrast agent suggestive of pancreatic duct.
Diagnosis of ectopic pancreas can be achieved radiographically but usually the definitive diagnosis is made during surgical or endoscopic evaluation. Imaging findings may be seen on upper gastrointestinal series (UGI), ultrasound (including endoscopic), computed tomography (CT), and magnetic resonance imaging (MRI). Features are frequently nonspecific. The mass is typically situated in the submucosa, but sometimes extends into the muscular wall resembling leiomyoma or other submucosal tumours.16,17 Diagnosis is difficult prospectively16 and is often made after biopsy or resection.14 In this article, we review the radiographic findings of heterotopic pancreas including the typical appearance in
Heterotopic pancreas is most often incidentally discovered in the upper gastrointestinal tract, with the stomach being the most common location.1 Lesions in the stomach range from 1–3 cm and are usually located along the greater curvature in the gastric antrum within 6 cm of the pylorus.1,12,18 The radiographic findings of heterotopic pancreas on UGI series are well described.12,18 The mass has a broad base and smooth surface characteristic of extra-mucosal intramural tumours. Occasionally, the lesion can appear sessile, with a narrow base and is mistaken for a gastric polyp. Umbilication manifested by pooling of barium is thought to represent the ductal remnant. Visualization of a bariumfilled pit at the centre of the lesion permits the specific diagnosis of heterotopic pancreatic tissue (Fig. 1).18 Larger umbilications present a diagnostic dilemma and are often mistaken for gastric ulcers or ulcerating intramural tumours. On ultrasound/endoscopic ultrasound heterotopic pancreas often appears as a solid submucosal mass (Fig. 2b–c) of low echogenicity, compared to the hyperechoic submucosa, and isoechoic to the hypoechoic muscularis propria layer.19,20 At CT a prospective diagnosis of heterotopic pancreas is challenging. Masses are often oval or round with smooth or serrated margins in the gastric antral wall16 (Fig. 3). Often there is homogeneous early enhancement, similar to the normal pancreas. Occasionally, poor enhancement is seen, in which case lesions have been shown to consist primarily of ducts and hypertrophied muscle.17 A minority of cases show dilatation of heterotopic pancreatic duct. Water has been proposed as an oral contrast agent due to improved depiction of the submucosal location of the heterotopic pancreas during the portal phase or non-equilibrium phase of scanning, although it has not been demonstrated to improve the preoperative diagnostic rate.16
Figure 2 A 49-year-old man with epigastric pain and heterotopic pancreas in the stomach. (a) Coronal, T2-weighted image demonstrating a smoothly marginated submucosal lesion of high signal intensity on T2-weighted imaging (white arrow). Note the dilated ectopic pancreatic duct. (b) Endoscopy demonstrating a 1–2 cm submucosal lesion in the proximal antrum. (c) Endoscopic ultrasound was performed using a radial echoendoscope at 7.5 MHz. A hypoechoic homogeneous antral mass (black arrowheads) is consistent with a heterotopic pancreatic rest.
J.W. Kung et al. / Clinical Radiology 65 (2010) 403–407
405
Figure 3 A 61-year-old man with asymptomatic heterotopic pancreas. Contrast-enhanced CT image acquired in the portal venous phase demonstrates a submucosal mass (black arrow) of homogeneous attenuation similar to the pancreatic parenchyma, along the greater curvature of the gastric antrum.
MRI findings of heterotopic pancreas in the stomach have not been well described. The signal characteristics and enhancement of heterotopic pancreas should parallel those of the native pancreatic gland. However, intense enhancement greater than that of normal pancreas may be seen (Fig. 4). The normal pancreatic parenchyma typically exhibits a signal intensity similar to (in older patients) or higher than (younger patients) the normal liver parenchyma on T1-weighted images21 (Fig. 4b). MR cholangiopancreatography (MRCP) is usually performed with heavily T2-weighted images. Evaluation with MRCP or typical T2-weighted sequences may allow identification of the ‘‘ectopic duct sign,’’ a dilated ectopic pancreatic duct (Fig. 2a). In these cases, the mass demonstrates predominantly high signal intensity on the T2-weighted images. The use of secretin during the MRCP examination may improve the visualization of the ductal system in the heterotopic pancreas.
Figure 5 A 41-year-old woman with heterotopic pancreas in the oesophagus. Double contrast barium oesophagram demonstrating a broad-based submucosal lesion (white arrows). Note the obtuse angles between the mass and mucosa indicating the submucosal location.
Atypical locations of heterotopic pancreas Atypical locations of heterotopic pancreas include the ileum, Meckel’s diverticulum, common bile duct, umbilicus, gallbladder, omentum, spleen, mediastinum, and fallopian
Figure 4 A 61-year-old man with asymptomatic heterotopic pancreas (same patient as Fig. 3). (a) Axial, three-dimensional, fat-saturated, T1-weighted, spoiled-gradient echo image of the upper abdomen shows a heterogeneous submucosal lesion (white arrow) along the greater curvature of the antrum. (b) Axial, three-dimensional, fat-saturated, T1-weighted, spoiled-gradient, echo image of the upper abdomen acquired during the portal venous phase demonstrates avid enhancement of greater curvature mass (white arrow). Note the normal pancreas.
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J.W. Kung et al. / Clinical Radiology 65 (2010) 403–407
Figure 6 A 22-year-old woman with heterotopic pancreatitis. (a) Coronal, contrast-enhanced CT image demonstrates enhancing nodular mass (black arrow) abutting a loop of small bowel with inflammatory change in the mesentery (white arrows). Note the normal appearance of the pancreas. (b) Axial, three-dimensional, fat-saturated, T1-weighted, spoiled gradient echo image of the upper abdomen in the same patient demonstrates the nodular lesion (white arrow), now in the left upper quadrant with associated inflammation (arrowheads). (c) Axial, threedimensional, fat-saturated, T1-weighted, spoiled gradient echo image demonstrating normal appearance of the pancreas (white arrows). Note the similar appearance of the mass and the normal pancreas, which exhibits bright signal intensity. (d) Axial, three-dimensional, T2-weighted MRI image demonstrates nonspecific inflammation within the left upper quadrant (white arrowheads). A small fluid collection (white arrow) is noted in the centre. (e) MR cholangiopancreatogram demonstrates inflammation in the left upper (small white arrow) and right lower (large white arrow) quadrants. The common bile duct and pancreatic duct (white arrowheads) are well visualized. At surgery a mobile mass in the jejunal mesentery was found. Pathological evaluation revealed ectopic pancreas with mesenteric inflammation secondary to pancreatitis.
tubes.1,4–6 Heterotopic pancreas in the oesophagus is rare and primarily described in the surgical and gastroenterology literature.19 On barium oesophagram, the lesion presents as a broad based submucosal mass (Fig. 5). Findings on CT and MRI are equally nonspecific.
Atypical presentations of heterotopic pancreas Many patients with heterotopic pancreas are presumably asymptomatic and most heterotopic pancreas goes
Figure 7 A 46-year-old man with heterotopic gastric pancreas and cystic pancreatic ductal dilatation. (a) Unenhanced axial CT image demonstrates a solid and cystic mass (white arrow), arising from the greater curvature of the stomach with coarse calcifications (black arrowhead) suggestive of chronic pancreatitis. (b) Axial, contrast-enhanced CT image acquired in the portal venous phase demonstrates a nodular and solid (white arrow) component to the mass. Notice that the solid component has enhancement characteristics similar to the normal pancreatic gland (black arrowheads). (c) Enhanced, coronal CT image demonstrating the predominantly multiloculated cystic nature of the mass (asterisks).
J.W. Kung et al. / Clinical Radiology 65 (2010) 403–407
undetected until incidentally detected at surgery or at autopsy. However, heterotopic pancreas can undergo inflammatory changes (i.e., pancreatitis) similar to the normal pancreatic gland. Inflamed heterotopic pancreas in the mesentery or jejunal wall has been reported 14,16 and mistaken for jejunitis or jejunal tumour. Findings on CT are nonspecific and reveal an ovoid soft-tissue mass in the small-bowel mesentery or jejunum with surrounding mesenteric oedema and thickening of the jejunal wall 13,14 (Fig. 6). The presence of a soft-tissue mass in the epicentre of the inflammatory changes with increased signal intensity on unenhanced T1-weighted images relative to the liver, similar to that of the normal pancreas, may be the key for the diagnosis. MRCP can be used to confirm the presence of a duct within the mass and allow conservative treatment.13 In the face of clinical findings suggestive of pancreatitis, including elevated serum concentrations of lipase and amylase with a normal looking pancreas, this diagnosis should be considered. Heterotopic pancreas can undergo cystic degeneration including cystic dystrophy, often in the duodenum and stomach.22 Evidence of chronic pancreatitis with associated pseudocyst or ectopic ductal dilation can best be seen using CT (Fig. 7). Strategically located heterotopic pancreatic tissue can result in symptoms of obstruction. Heterotopic pancreas at the gastro-oesophageal junction or gastric antrum has resulted in dysphagia19 and gastric obstruction.12 Presentation at the ampulla of Vater can lead to obstructive jaundice.23 Intussusceptions in which the lead point was a mass of heterotopic pancreas have been reported.5 Reports of malignant transformation are extremely rare.24 Heterotopic pancreas undergoes malignant transformation similar to the native gland. Adenocarcinoma, intraductal papillary mucinous neoplasm, and malignant insulinoma have been reported arising in heterotopic pancreatic tissue.5,24,25 The imaging findings are usually nonspecific and diagnosis is often made following surgical resection. In conclusion, we present a spectrum of fluoroscopic and cross-sectional imaging appearances of heterotopic pancreatic tissue that may help suggest the correct diagnosis preoperatively and guide clinical management.
References 1. Dolan RV, ReMine WH, Dockerty MB. The fate of heterotopic pancreatic tissue. A study of 212 cases. Arch Surg 1974;109:762–5.
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