Heterotopic pancreas: presentation as jejunal tumor

Intraductal papillary mucinous neoplasm originating from a jejunal heterotopic pancreas: A case report

BACKGROUND

Intraductal papillary mucinous neoplasm (IPMN) is a rare pancreatic tumor and has the potential to become malignant. Surgery is the most effective treatment at present, but there is no consensus on the site of resection. Heterotopic pancreas occurs in the gastrointestinal tract, especially the stomach and duodenum but is asymptomatic and rare. We report a case of ectopic pancreas with IPMN located in the jejunum.

CASE SUMMARY

A 56-year-old male patient suffered from severe pain, nausea and vomiting due to a traffic accident and sought emergency treatment at our hospital. Contrast-enhanced computed tomography of the whole abdomen suggested splenic congestion, which was considered to be splenic rupture. Emergency laparotomy was performed, and the ruptured spleen was removed during the operation. Unexpectedly, a cauliflower-like mass of about 2.5 cm × 2.5 cm in size was incidentally found about 80 cm from the ligament of Treitz during the operation. A partial small bowel resection was performed, and postoperative pathology confirmed the small bowel mass as heterotopic pancreas with low-grade IPMN.

CONCLUSION

Ectopic pancreas occurs in the jejunum and is pathologically confirmed as IPMN after surgical resection.

Insight into gastrointestinal heterotopic pancreas: imaging evaluation and differential diagnosis

Heterotopic pancreas (HP) is an uncommon congenital abnormality in the developmental process of the pancreas, with gastrointestinal heterotopic pancreas (GHP) being the most common HP. The clinical manifestations of GHP may have variable patterns of presentation, dictated by both the anatomic location and the functional ability of the lesion. The most common imaging modality in detecting GHP is computed tomography (CT), while gastrointestinal barium fluoroscopy, endoscopic ultrasonography, and magnetic resonance imaging (MRI) are also applied. The density and enhancement patterns of GHP are consistent with histological classifications. GHP with a predominantly acinar tissue component manifests homogeneous and marked enhancement on CT images, whereas a predominantly ductal GHP presents heterogeneous and mild enhancement. On MRI, the appearance and signal intensity of GHP were paralleled to the normal pancreas on all sequences and were characterized by T1-weighted high signal and early marked enhancement. This article provides a comprehensive review of the histopathology, clinical manifestations, imaging features of various modalities, and differential diagnosis of GHP. It is hoped that this review will improve clinicians' knowledge of GHP and aid in accurate preoperative diagnosis, thereby reducing the misdiagnosis rate.

Differentiation between small (< 4.5 cm) true subepithelial tumors and ectopic pancreas in the small bowel on computed tomography enterography

OBJECTIVES

To identify imaging features that can differentiate ectopic pancreas from true subepithelial tumors (SETs) in the small bowel using CT enterography and to assess whether radiologists' performance for the differentiation can be improved with the knowledge of significant CT findings.

METHODS

CT images of ectopic pancreas (n = 29) and pathologically proven SETs (n = 61) were retrospectively reviewed by two radiologists in consensus. CT items analyzed included lesion location, contour (round, ovoid, flat/conformed), growth pattern, margin, homogeneity, necrosis, feeding vessel, surface ulceration, and enhancement pattern. For quantitative analysis, Hounsfield unit, longer diameter (LD), and shorter diameter (SD) of the lesion were measured. Univariate and multivariate analyses were performed. Diagnostic performance for differentiating ectopic pancreas from SETs was independently evaluated by two other radiologists using a receiver operating characteristic analysis.

RESULTS

Age < 63 years, female sex, flat/conformed appearance, homogeneous enhancement, the absence of feeding vessels and necrosis, and an LD/SD ratio > 1.5 were significant variables for differentiating ectopic pancreas from small bowel SETs (p < 0.05). In the multivariate analysis, flat/conformed appearance, the absence of feeding vessels, and female sex remained suggestive features for ectopic pancreas. Area under the curve values for differentiating between two disease entities increased by both independent reviewers with knowledge of these significant CT features.

CONCLUSIONS

Ectopic pancreas in the small bowel can be effectively differentiated from small (< 4.5 cm) true SETs by a flat/conformed appearance and the absence of feeding vessels on CT enterography. In addition, radiologists' performance for differentiating ectopic pancreas from small bowel SETs was improved with the knowledge of these significant CT findings.

KEY POINTS

• Ectopic pancreas in the small bowel can be differentiated from small (< 4.5 cm) subepithelial tumors on CT. • Differential CT findings of the ectopic pancreas are a flat or conformed appearance and the absence of a feeding vessel. • Radiologists' performance for differentiating ectopic pancreas from small bowel SETs can be improved with the knowledge of differential CT findings.

Pancreatitis in the developmentally anomalous pancreas

Developmental anomalies of the pancreas include more common entities such as pancreas divisum and annular pancreas, and unusual entities such as heterotopic pancreas. While these anomalies can present a diagnostic challenge to the radiologist, when the pancreatic tissue involved in these processes develops pancreatitis, the radiographic appearance can present a diagnostic dilemma. Awareness of these pancreatic anomalies and familiarity with their appearance when inflamed is necessary to distinguish pancreatitis in the developmentally anomalous pancreas from other inflammatory or neoplastic processes.

Heterotopic Pancreas: Histopathologic Features, Imaging Findings, and Complications

Heterotopic pancreas is a congenital anomaly in which pancreatic tissue is anatomically separate from the main gland. The most common locations of this displacement include the upper gastrointestinal tract-specifically, the stomach, duodenum, and proximal jejunum. Less common sites are the esophagus, ileum, Meckel diverticulum, biliary tree, mesentery, and spleen. Uncomplicated heterotopic pancreas is typically asymptomatic, with the lesion being discovered incidentally during an unrelated surgery, during an imaging examination, or at autopsy. The most common computed tomographic appearance of heterotopic pancreas is that of a small oval intramural mass with microlobulated margins and an endoluminal growth pattern. The attenuation and enhancement characteristics of these lesions parallel their histologic composition. Acinus-dominant lesions demonstrate avid homogeneous enhancement after intravenous contrast material administration, whereas duct-dominant lesions are hypovascular and heterogeneous. At magnetic resonance imaging, the heterotopic pancreas is isointense to the orthotopic pancreas, with characteristic T1 hyperintensity and early avid enhancement after intravenous gadolinium-based contrast material administration. Heterotopic pancreatic tissue has a rudimentary ductal system in which an orifice is sometimes visible at imaging as a central umbilication of the lesion. Complications of heterotopic pancreas include pancreatitis, pseudocyst formation, malignant degeneration, gastrointestinal bleeding, bowel obstruction, and intussusception. Certain complications may be erroneously diagnosed as malignancy. Paraduodenal pancreatitis is thought to be due to cystic degeneration of heterotopic pancreatic tissue in the medial wall of the duodenum. Recognizing the characteristic imaging features of heterotopic pancreas aids in differentiating it from cancer and thus in avoiding unnecessary surgery. ^© RSNA, 2017.

Heterotopic pancreas of the jejunum: associations between CT and pathology features

PURPOSE

To investigate the computed tomography (CT) features of heterotopic pancreas of the jejunum (HPJ) and to assess their associations with HPJ pathology features.

METHODS

In this retrospective series analysis, two radiologists reviewed the CT images of 17 patients with surgically proven HPJ in order to determine in consensus the location, long diameter, margin, shape, contour, and growth pattern of the lesions, the presence of a duct-like structure, the lesion enhancement patterns, including the homogeneity, and the degree of contrast enhancement compared with that of the main pancreas. The pathology features of the surgical specimens were reviewed and their associations with the CT features were assessed.

RESULTS

On CT, the HPJs typically appeared as a small (<3 cm), well-defined, ovoid or flat-shaped mass in the proximal jejunum with multiple and tiny lobulations. The growth pattern varied and the duct-like structure was rarely visible. The HPJs mostly appeared to be homogeneous and exhibited hyper- or isoattenuation compared to the main pancreas in the arterial and portal phases. However, these enhancement patterns varied slightly depending on the microscopic composition of the lesions (i.e., acinar vs. ductal predominance). Most HPJs comprised histologically of large acini, some ducts, and small islet cells, and had ductal communication with the jejunum.

CONCLUSIONS

HPJs typically manifested as small, well-defined, ovoid or flat-shaped, homogeneous, and well-enhancing masses with a microlobulated contour in the proximal jejunum on CT, and their enhancement patterns associated with their microscopic composition. The pathology features of HPJs generally mimic those of the normal pancreas.

Enhanced CT and CT virtual endoscopy in diagnosis of heterotopic pancreas

AIM: To improve the diagnosis of heterotopic pancreas by the use of contrast-enhanced computed tomography (CT) imaging and CT virtual endoscopy (CTVE).

METHODS: A total of six patients with heterotopic pancreas, as confirmed by clinical pathology and immunohistochemistry in the Sixth Affiliated People’s Hospital of Shanghai Jiao Tong University, Shanghai, China, were included. Non-enhanced CT and enhanced CT scanning were performed, and the resulting images were reviewed and analyzed using three-dimensional post-processing software, including CTVE.

RESULTS: Four males and two females were enrolled. Several heterotopic pancreas sites were involved; three occurred in the stomach, including the gastric antrum (n = 2) and lesser curvature (n = 1), and two were in the duodenal bulb. Only one case of heterotopic pancreas lesion occurred in the mesentery. Four cases had a solid yet soft tissue density that had a homogeneous pattern when viewed by enhanced CT. Additionally, their CT values were similar to that of the pancreas. The ducts of the heterotopic pancreas tissue, one of the characteristic CT features of heterotopic pancreas tissue, were detected in the CT images of two patients. CTVE images showed normal mucosa around the tissue, which is also an important indicator of a heterotopic pancreas. However, none of the CTVE images showed the typical signs of central dimpling or umbilication.

CONCLUSION: CT, enhanced CT and CTVE techniques provide useful information about the location, growth pattern, vascularity, and condition of the gastrointestinal wall around heterotopic pancreatic tissue.

Heterotopia pancreática: análise clínico-patológica de 18 doentes

OBJETIVO: Analisar as características clínico-patológicas do tecido pancreático heterotópico em órgãos digestivos abdominais. MÉTODOS: Realizamos estudo retrospectivo analisando 18 portadores de pâncreas heterotópico diagnosticados histologicamente. Seus dados clínicos e histopatológicos foram revistos. O tecido pancreático heterotópico foi classificado em três modelos histológicos: tipo I constituído por três componentes do pâncreas normal (ácinos, ductos e ilhotas), tipo II com dois componentes e tipo três com somente um componente. RESULTADOS: A média de idade foi de 52,7 anos, variando de 34 a 73 anos, com nove homens e nove mulheres. Sintomas foram observados em somente quatro doentes, sendo suas lesôes diagnosticadas por gastroscopia. Os 14 restantes eram assintomáticos e suas anomalias descobertas acidentalmente. A maioria das lesões situava-se no trato superior: sete (38,9%) no estômago, seis (33,3%) no duodeno e três (16,6%) no jejuno. A heterotopia localizou-se preferencialmente na submucosa (83,3%), mas também foi observada na muscular própria e na sub-serosa. Em sete (38,9%) espécimes todos os componentes pancreáticos foram constatados (tipo I), em oito (44,4%) estavam presentes glândulas exócrinas e ductos excretores (tipo II) e em três (16,7%) somente o tecido exócrino foi observado (tipo III). CONCLUSÃO: A heterotopia pancreática é rara. Doentes com ectopia pancreática diagnosticadas pelo estudo patológico, assintomáticos ou com sintomas discretos devem permanecer em observação. As lesões detectadas acidentalmente durante procedimentos cirúrgicos necessitam ser removidas por procedimentos conservadores.