CASE 17059 Published on 20.11.2020

Teaching Case

Section

Abdominal imaging

Case Type

Clinical Cases

Authors

Leonardo Giarraputo MD, Sergio Savastano MD, Silvia Ceccato MD, Elisa Chemello MD, Mariacristina Maturi MD, Caterina Zivelonghi MD.

Department of Radiology, San Bortolo Hospital, V.le Rodolfi n.37, 36100 Vicenza, Italy

Patient

72 years, male; 50 years, male

Categories

Area of Interest Anatomy, Pancreas ; Imaging Technique CT, MR ;

No Procedure ; No Special Focus ;

Show more Show less

View full case Show related cases Notify admin

Clinical History

Case 1. A 72-year-old man referred to our Department for an MRI of the upper abdomen to rule out a hepatic lesion detected by abdominal sonography performed in a private centre.

Case 2. A 50-year-old man investigated with an abdominal MRI for a renal angiomyolipoma.

Differential Diagnosis List

Log in to take the quiz and to see the final diagnosis

Circumportal annular pancreas - suprasplenic variant

Pancreatic tumour

Peripancreatic adenopathy

Pancreatitis

Imaging Findings

Case 1. The head of the pancreas encircling the vena porta was incidentally detected on MRI (Fig. 1A). On a more caudal scan, at the level of the splenoportal junction, the uncinate process appeared normal (Fig. 1B). The bridge of the pancreatic tissue posterior to the vena porta did not show any abnormal signal intensity. The Wirsung duct was not dilated. Revision of an abdominal CT performed 7 years ago evidenced a similar finding (Fig. 2).

Case 2. MRI demonstrated a thin layer of a normal pancreatic tissue encompassing the proximal segment of the porta vein above the splenoportal junction (Fig. 3).

Discussion

Development anomalies of the pancreas are not wholly elucidated. Pancreas embryogenesis is genetically determined by molecules promoting or inhibiting development and differentiation of exocrine and endocrine cells lines from the embryo foregut [1-3]. Morphogenesis misregulation results in an overgrowth of the pancreas (annular pancreas or pancreatic heterotopias), or, more rarely, in agenesia or hypoplasia of the pancreas [3].

The pancreas develops from two diverticula of the embryonic foregut approximately during the fourth gestational weeks [4-9]. The smaller ventral bud gives rise to the uncinate process and the posterior part of the pancreatic head whereas the larger dorsal anlagen gives rise to the tail, the body and the anterior part of the pancreatic head.

The final configuration of the pancreas is related to the counterclockwise rotation of the embryonic foregut; alternatively, Kin et al. hypothesized the dominant growth of the dorsal bud induces the passive dislocation of the ventral anlagen posteriorly to the duodenum before the two buds fuse at the seventh gestational week [4].

A circumportal annular pancreas (CPAP) is a normal findings in swine [4, 10, 11], but it was considered extremely rare in humans. After the first report by Sugiura et al. in 1987 [12], revision of radiologic series evidenced a prevalence of a CPAP of 1.1-2.5% in general population [4, 13, 14].

According to the relationship between the pancreatic bridge and the splenoportal junction the CPAP is distinguished in suprasplenic (Type A, the more frequent), infrasplenic (Type B) or mixed (Type C); the course of the main pancreatic duct can be retroportal (Type I, the most common), retroportal with pancreas divisum (Type II) ore anteroportal (Type III) [15].

The CPAP is asymptomatic and thus often underdiagnosed by radiologists. Anyway, it is challenging for the surgeon because technical difficulties in dissecting the vena porta, pancreaticojejunal reconstruction, and the high complication risk of a postoperative pancreatic fistula [15]. Moreover, radiologists should always report any vascular anomalies, such as celiac trunk variants or an aberrant common or right hepatic artery, since they make additional difficulties to the surgeon.

A CPAP can be easily detected both by non-enhanced and contrast-enhanced CT or MRI [16-18], which demonstrate a normal pancreatic bridge encircling the portal vein. Contrast-enhanced imaging is mandatory to delineate the anatomic relationship between the CPAP and vessels; when detailed imaging of the main pancreatic duct is required, paracoronal and paraxial MRCPs are mandatory.

Written informed patient consent for publication has been obtained

References

[1] Savastano S, Alessi S, Fantozzi O et al. (2004) MRI diagnosis of a periportal annular pancreas. Eur J Radiol Extra 50:93-95

[2] Kim SK, Melton DA (1998) Pancreas development is promoted by cyclopamine, a hedgehog signaling inhibitor. Proc Natl Acad Sci USA 95:13036-13041. (PMID 31039791)

[3] Hebrok M, Kim SK, St-Jacques B et al. (2000) Regulation of pancreas development by hedgehog signalling Development 127:4905–13 (PMID 11044404)

[4] Arora A, Velayutham P, Rajesh S, et al. (2014) Circumportal pancreas: a clinicoradiological and embryological review. Surg Radiol Anat 36:311-319 (PMID 23982900)

[5] Alexander LF (2012) Congenital pancreatic anomalies, variants, and conditions Radiol Clin North Am 50:487–498 (PMID 22560693)

[6] Mortelé KJ, Rocha TC, Streeter JL, Taylor AJ (2006) Multimodality imaging of pancreatic and biliary congenital anomalies Radiographics 26:715–731 (PMID 16702450)

[7] Nijs EL, Callahan MJ (2007) Congenital and developmental pancreatic anomalies: ultrasound, computed tomography, and magnetic resonance imaging features. Semin Ultrasound CT MR 28:395–401 (PMID 17970555)

[8] Pokorny WJ, Rothenberg SS, Brandt ML. Growth and development. In: O‘Leary JP (ed) The physiologic basis of surgery, 3rd ed. Lippincott Williams and Wilkins (2002) Philadelphia, pp 64–65

[9] Schulte SJ. Embryology, normal variation, and congenital anomalies of the pancreas. In: Margulis’ and Burhenne alimentary tract radiology, 5th edn. Mosby, St Louis (1994), pp 1039–1051

[10] Skjennald A (1982) Anatomy of the liver and pancreas in the domestic swine, with special reference to vascular structures. Scand J Gastroenterol 17:16–31 28.

[11] Truty MJ, Smoot RL (2008). Animal models in pancreatic surgery: a plea for pork. Pancreatology 8:546–550. (PMID 18824879)

[12] Sugiura Y, Shima S, Yonekawa H et al. (1987). The hypertrophic uncinate process of the pancreas wrapping the superior mesenteric vein and artery. A case report. Jpn J Surg 17:182–185. (PMID 3626212)

[13] Ishigami K, Tajima T, Nishie A, et al. (2011). The prevalence of circumportal pancreas as shown by multidetector-row computed tomography Insights Imaging 2:409-414. (PMID 22347962)

[14] Karasaki H, Mizukami Y, Ishizaki A, et al. (2009). Portal annular pancreas, a notable pancreatic malformation: frequency, morphology, and implications for pancreatic surgery. Surgery 146:515-518. (PMID 19715809)

[15] Luu AM, Braumann C, Herzog T, et al. (2017). Circumportal Pancreas. A Must Know Pancreatic Anomaly for the Pancreatic Surgeon. J Gastrointest Surg 21:344-351. (PMID 27826941)

[16] Arora A, Velayutham P, Rajesh S, et al. (2014). Circumportal pancreas: a clinicoradiological and embryological review. Surg Radiol Anat 36:311-319. (PMID 23982900)

[17] Gonoi W, Akahane M, Akai H et al. (2011). Retroportal main pancreatic duct with cir cumportal pancreas: radiographic visualization. Clin Imaging 35:442–446. (PMID 22040788)

[18] Joseph P, Raju RS, Vyas FL, et al. (2010). Portal annular pancreas. A rare variant and a new classification. JOP 11:453-455. (PMID 20818114)

Case information