Annular Pancreas

Clinical

Annular pancreas is a rare congenital abnormality in which a ring of pancreatic tissue encircles the duodenum at or above the major papilla. Embryologically it is a sequelae of a persistent left ventral bud, which usually atrophies during embryological development.

The usual presentation of annular pancreas is SBO. Annular pancreas compressing the second (descending) portion of the duodenum. The degree of SBO caused by annular pancreas varies dramatically from being asymptomatic to presenting as a surgical abdomen in a newborn. It may become symptomatic in adulthood as SBO, with abdominal pain, early satiety, and vomiting. There is also an increased incidence of peptic ulcer disease and pancreatitis. Annular pancreas is discussed in more detail in the Pancreas section.

Radiology

Plain films may demonstrate proximal small bowel obstruction.

Fluoroscopy more clearly delineates the abnormality. It will show dilatation of the proximal duodenum, with eccentric or concentric narrowing of descending duodenum. In the most severe cases, mucosal effacement will be seen. Note that there is NO ulceration or mucosal destruction, differentiating it from neoplastic or inflammatory etiologies.

CT is beneficial for diagnosis confirmation, as it will demonstrate the ring of pancreatic tissue surrounding and compressing the duodenum.

Annular pancreas. Fluoroscopy demonstrates concentric narrowing of the second portion of the duodenum.