Rare Syndromes

Congenital Abnormalities

 Annular Pancreas – is usually a band of pancreatic tissue that completely encircles the second portion of the duodenum, and may cause duodenal stenosis.  Annular pancreas is a rare finding (~3/20,000 autopsies).  Theoretically annular pancreas may occur embryonically when the ventral bud  becomes fixed and fails to rotate.  This hypothesis is supported by the usual finding of the duct encircling the pancreas from anterior to posterior around the right side to join the common bile duct.  Other variants have also been seen.  Annular pancreas is frequently observed in conjunction with other congenital defects including intestinal malrotation, cardiac defects, Meckel’s diverticuli, imperforate anus, and spinal defects.  It is common in Down’s syndrome.  The classic presentation is a vomiting infant with the characteristic “double bubble” sign on radiographic imaging.

Ectopic pancreatic tissue–may occur from displacement of small amounts of pancreas during embryonic development, resulting in the formation of a nodule which is independent of the pancreas. Ectopic pancreatic tissue, or pancreatic rest, is relatively common on careful histologic examination (1-14% of autopsy cases), but typically it is not of clinical significance.  Ectopic tissue is usually seen in the stomach, duodenum, and jejunum, but foci of pancreatic tissue have been reported throughout the gastrointestinal tract.  It is rare for ectopic pancreatic tissue to cause symptoms or require treatment, but, infrequently, pancreatitis or pancreatic cancer may develop in the tissue.

Congenital Pancreatic Insufficiency Syndromes

These two symptoms represent failure of the acinar cells, whereas cystic fibrosis affects the ductal cells.

Shwachman-Diamond Syndrome – is an autosomal recessive disorder characterized by pancreatic insufficiency, cyclic neutropenia, metaphyseal dysostosis, and growth retardation (1).  Sweat chloride is normal.  The gene defect is near the centromere of chromosome 7 and involves a newly discovered gene, the Shwachman-Bodian-Diamond Syndrome gene (SBDS)  (2), which appears to be involved with RNA processing.

 Johanson-Blizzard Syndrome – is an autosomal recessive disorder characterized by pancreatic insufficiency, nasal alar hypoplasia, tooth abnormalities, short stature, psychomotor retardation, congenital deafness and ectodermal scalp defects.  Fewer than 40 cases have been reported. The gene appears to be associated with ubiquination of proteins.

Ductal System Malformation

The pancreatic ductal systems usually merge and join the common bile duct and empty into the duodenum through the ampulla of Vater (major papilla).  In ~33% of people, the accessory duct is patent and empties through the duct of Santorini via the minor papilla.

Pancreatic divisum

 In 5-10% of people, the ducts do not fuse.  In these cases, the majority of the pancreas must drain through the narrow minor papilla.  This condition is often associated with recurrent acute pancreatitis.

The figure to the left illustrates the most common form of pancreas divisum.

Common Channel Syndrome – In some patients, an abnormally long (>10 mm in children) common pancreatobiliary channel occurs  (3). The junction remains outside of the duodenal wall and lacks the normal sphincter.  The result may be pancreatobiliary reflux and injury to the extrahepatic bile duct. Clinical presentations include choledochal cysts (below) or recurrent acute pancreatitis.

Choledochal Cyst  – Choledochal cyst are divided into three types:

1. Cystic dilations of the entire extrahepatic duct
2. Saccular dilatation of portions of the duct
3. Cystic dilatation of the intraduodenal duct (choledochocele)

(Intrahepatic dilation is Caroli’s disease.)

Choledochal cysts often present in childhood with right upper quadrant (RUQ) pain and jaundice, but may be an incidental finding during ERCP.  These cysts are more often seen in Asian countries.  Surgical removal is the treatment of choice. The incidence of carcinoma in these cysts is very high and has even been reported in children.

References

1. Kakkar N, Vasishta RK, Marwaha N, Marwaha RK. Special feature: pathological case of the month. Shwachman-Diamond syndrome: a syndrome of pancreatic insufficiency and bone marrow dysfunction. Arch Pediatr Adolesc Med. 2001;155(5):611-2.
2. Boocock GR, Morrison JA, Popovic M, Richards N, Ellis L, Durie PR, et al. Mutations in SBDS are associated with Shwachman-Diamond syndrome. Nat Genet. 2003;33(1):97-101.
3. Jan DM. The Panceas: Congenital anomalies. In: Walker WA, Goulet O, Kleinman RE, Sherman PM, Shneider BL, Sanderson IR, editors. Pediatric Gastrointestinal Disease: Pathophysiology, Diagnosis, Management. Hamilton (ON): BC: Decker; 2004. p. 1566-70.