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Special Feature |

Image of the Month—Diagnosis FREE

Arch Surg. 2005;140(9):912-913. doi:10.1001/archsurg.140.9.912.
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ANSWER: HETEROTOPIC (ECTOPIC) PANCREAS OF ILEUM

On opening the surgical specimen, the center portion of the lobulated nodule showed the presence of umbilication. Light microscopy showed that the lesion was located in the submucosa of the ileum and was composed of pancreatic acinar cells, pancreatic ducts, and islets of Langerhans (Figure 1 and Figure 2). No malignant transformation was found. The mucosal and serosal surfaces of the ileum were normal. The pathological diagnosis was heterotopic (ectopic) pancreas of the ileum.

Place holder to copy figure label and caption
Figure 1.

The lesion, situated within the submucosa of the ileum, shows evidence of pancreatic ducts and acinar cells. Ileum mucosa is visible at the lower right (hematoxylin-eosin, ×100).

Graphic Jump Location
Place holder to copy figure label and caption
Figure 2.

Histological specimen of the lesion, which is composed of pancreatic ducts, acinar cells, and islets of Langerhans (hematoxylin-eosin, ×100).

Graphic Jump Location

Heterotopic, ectopic, or aberrant pancreatic tissue, also known as a pancreatic rest, is an uncommon congenital anomaly defined as extra pancreatic tissue located far from the pancreas and without connection via vascular or anatomical means to it.1 Several theories have been advanced to explain the pathogenesis and occurrence of heterotopic pancreas. The most tenable and plausible implicates migration and/or rests of branching pancreatic tissue buds from the developing pancreas during embryogenesis.2 The first reported case of heterotopic pancreatic tissues was described in 1729, but it was not until 1859 that histological confirmation was provided by Klob.3 Heterotopic pancreatic tissues have been reported to occur throughout the digestive tract, the most frequent site being the upper gut, including the stomach, duodenum, and jejunum.4 Uncommon locations are the colon, spleen, liver, biliary tract, mesentery, and lymph nodes.1,4 Heterotopic pancreas found in the ileum is rare.

Pathologically, a mass of heterotopic pancreas generally ranges from 0.2 to 3.0 cm in its greatest dimension (average size, 1.1 cm) and usually presents as a well-circumscribed, soft, rubbery, yellow, submucosal or intramural mass.2,5 Some demonstrate central umbilication or ulceration on radiographic contrast studies. Histologically, herotopic pancreas has been divided into 4 types2: type I is total pancreatic heterotopia, which is composed of all pancreatic cell types; type II contains pancreatic ducts only; type III is composed of acinar cells only; and type IV is composed of islet cells only. Our case is an example of type I and had all of the histological characteristics of the pancreas, including acinar cells, islets of Langerhans, and pancreatic ducts. This is typical of extra pancreatic tissue.

Most patients with heterotopic pancreas are free of symptoms and a diagnosis before surgery is difficult. Such cases are usually discovered during radiographic or endoscopic examination of the gut, or during surgical exploration for other disease. Although the most common symptoms attributed to heterotopic pancreas, such as abdominal pain, nausea, vomiting, anemia, weight loss, and melena, are present at the time of diagnosis,6 this lesion has no specific clinical features. Endoscopic ultrasonography often shows a submucosal bulge covered by normal mucosa with or without central umbilication.1,7 Endoscopic ultrasonography seems to be a reliable method for providing the precise localization, extent, and characteristics of the submucosal mass, allowing one to differentiate it from all other types of masses such as tumors. However, the final diagnosis of pancreatic heterotopia is often reached by histological examination of surgical specimens.

The complications of heterotopic pancreas usually include inflammation with formation of an inflammatory mass, ulceration, bleeding and obstruction, and pancreatitis.5 Malignant transformation is possible and carcinoma of the heterotopic pancreas has been reported.2,8,9 The 3 criteria for a carcinoma arising from heterotopic pancreatic tissue that have been reported by Makhlouf et al4 may prevent its misinterpretation as a metastatic tumor.

Armstrong et al10 reported that differentiation from a leiomyoma or an adenomatous polyp is sometimes difficult; in addition, when the central umbilication is larger than usual, heterotopic pancreas may be confused with the base of a gastric or duodenal peptic ulcer. The leiomyoma produces a smooth elevation in the mucosa and may have central umbilication, but radiography will not show the presence of ducts. A small nodule of heterotopic pancreas cannot be distinguished easily from an adenomatous or regenerative polyp, but a polyp is usually larger and does not show central umbilication.

The management of heterotopic pancreatic tissues is somewhat controversial. Endoscopic removal is at risk of perforation or bleeding because the lesion is submucosal. Operative treatment is considered not only for complicated cases, such as bleeding, obstruction, and malignant transformation, but also for a definitive diagnosis to exclude a neoplastic lesion in symptomatic patients. Furthermore, our opinion is that when heterotopic pancreas is found incidentally, it is advisable to resect it intraoperatively to avoid late complications and a second operation, as well as to avoid the risk of malignant transformation.

In conclusion, we describe a 2.0-cm-diameter mass of heterotopic pancreas involving the ileum in a 62-year-old man. This patient was asymptomatic, and the lesion was found incidentally during emergency surgery. All histological features of the pancreas were seen in the surgical specimen. We recommend that heterotopic pancreas be treated with surgical excision, especially when it is found incidentally during an abdominal operation, to avoid late complications and malignant transformation.

Box Section Ref ID

Submissions

The Editor welcomes contributions to the “Image of the Month.” Send manuscripts to Archives of Surgery, Johns Hopkins Medical Institutions, 720 Rutland Ave, Ross 759, Baltimore, MD 21205; (443) 287-0026; e-mail: archsurg@jama-archives.org. Articles and photographs accepted will bear the contributor’s name. Manuscript criteria and information are per the “Instructions for Authors” for Archives of Surgery. No abstract is needed, and the manuscript should be no more than 3 typewritten pages. There should be a brief introduction, 1 multiple-choice question with 4 possible answers, and the main text. No more than 2 photographs should be submitted. There is no charge for reproduction and printing of color illustrations.

Correspondence: Bo-Guang Fan, MD, PhD, Department of Surgery, Taizhou Hospital, Taizhou Linhai, Zhejiang Province, China (fanboguang@gmail.com).

Accepted for Publication: April 8, 2005.

Acknowledgment: We thank Shuangqi Yang, CPM, for kind technical support during preparation of the illustration.

Shalaby  MKochman  MLLichtenstein  GR Heterotopic pancreas presenting as dysphagia. Am J Gastroenterol 2002;971046- 1049
PubMed Link to Article
Chetty  RWeinreb  I Gastric neuroendocrine carcinoma arising from heterotopic pancreatic tissue. J Clin Pathol 2004;57314- 317
PubMed Link to Article
Tanaka  KTsunda  TEto  T  et al.  Diagnosis and management of heterotopic pancreas. Int Surg 1993;7832- 35
PubMed
Makhlouf  HRAlmeida  JLSobin  LH Carcinoma in jejunal pancreatic heterotopia. Arch Pathol Lab Med 1999;123707- 711
PubMed
Bauer  PKWakely  PE Pathologic quiz case: a man with a retroperitoneal mass and a jejunal mass. Arch Pathol Lab Med 2003;127e237- e238
PubMed
Matsumoto  YKawai  YKimura  K Aberrant pancreas causing pyloric obstruction. Surgery 1974;76827- 829
PubMed
Monig  SPSelzner  MRaab  MEidt  S Heterotopic pancreas: a difficult diagnosis. Dig Dis Sci 1996;411238- 1240
PubMed Link to Article
Guillou  LNordback  PGerber  CSchneider  RP Ductal adenocarcinoma arising in a heterotopic pancreas situated in a hiatal hernia. Arch Pathol Lab Med 1994;118568- 571
PubMed
Herold  GKraft  K Adenocarcinoma arising from ectopic gastric pancreas: two case reports with a review of the literature. Z Gastroenterol 1995;33260- 264
PubMed
Armstrong  CPKing  PMDixon  JMMacleod  IB The clinical significance of heterotopic pancreas in the gastrointestinal tract. Br J Surg 1981;68384- 387
PubMed Link to Article

Figures

Place holder to copy figure label and caption
Figure 1.

The lesion, situated within the submucosa of the ileum, shows evidence of pancreatic ducts and acinar cells. Ileum mucosa is visible at the lower right (hematoxylin-eosin, ×100).

Graphic Jump Location
Place holder to copy figure label and caption
Figure 2.

Histological specimen of the lesion, which is composed of pancreatic ducts, acinar cells, and islets of Langerhans (hematoxylin-eosin, ×100).

Graphic Jump Location

Tables

References

Shalaby  MKochman  MLLichtenstein  GR Heterotopic pancreas presenting as dysphagia. Am J Gastroenterol 2002;971046- 1049
PubMed Link to Article
Chetty  RWeinreb  I Gastric neuroendocrine carcinoma arising from heterotopic pancreatic tissue. J Clin Pathol 2004;57314- 317
PubMed Link to Article
Tanaka  KTsunda  TEto  T  et al.  Diagnosis and management of heterotopic pancreas. Int Surg 1993;7832- 35
PubMed
Makhlouf  HRAlmeida  JLSobin  LH Carcinoma in jejunal pancreatic heterotopia. Arch Pathol Lab Med 1999;123707- 711
PubMed
Bauer  PKWakely  PE Pathologic quiz case: a man with a retroperitoneal mass and a jejunal mass. Arch Pathol Lab Med 2003;127e237- e238
PubMed
Matsumoto  YKawai  YKimura  K Aberrant pancreas causing pyloric obstruction. Surgery 1974;76827- 829
PubMed
Monig  SPSelzner  MRaab  MEidt  S Heterotopic pancreas: a difficult diagnosis. Dig Dis Sci 1996;411238- 1240
PubMed Link to Article
Guillou  LNordback  PGerber  CSchneider  RP Ductal adenocarcinoma arising in a heterotopic pancreas situated in a hiatal hernia. Arch Pathol Lab Med 1994;118568- 571
PubMed
Herold  GKraft  K Adenocarcinoma arising from ectopic gastric pancreas: two case reports with a review of the literature. Z Gastroenterol 1995;33260- 264
PubMed
Armstrong  CPKing  PMDixon  JMMacleod  IB The clinical significance of heterotopic pancreas in the gastrointestinal tract. Br J Surg 1981;68384- 387
PubMed Link to Article

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