Crocodile-jaw partial annular pancreas

Clinical History

An otherwise healthy 48-year-old female patient was being evaluated for chronic liver disease.

Imaging Findings

During contrast enhanced CT of abdomen, incidental note was made of an unusual morphology of the pancreatic head. The head of pancreas was seen extending anterior and posterior to the duodenum and partially encasing it, giving rise to a crocodile jaw appearance on the axial sections. There was no upstream bowel dilatation present.

Discussion

Annular pancreas is a rare congenital anomaly of the pancreas characterised by the presence of a ring of pancreatic tissue continuous with the head of the pancreas encircling the second part of the duodenum. Annular pancreas can be complete or partial [1].

Annular pancreas is a developmental abnormality that occurs during the early development of the foregut with a contentious aetiopathogenesis. It is presumably due to failure of the ventral bud to rotate behind the duodenum, leaving pancreatic tissue encircling the second portion of the duodenum. Other proposed theory is the growth of the bifid ventral pancreatic bud around the duodenum, which fuses with the dorsal bud to form a pancreatic ring [1-4].

Complete annular pancreas is usually diagnosed in neonates or infants, where it presents as duodenal obstruction. In adults, annular pancreas can manifest clinically as peptic ulcer disease, duodenal obstruction, pancreatitis, or obstructive jaundice [2, 3]. Partial annular pancreas tends to be clinically silent; but, at times can present with gastric outlet obstruction.

Radiologically incomplete annular pancreas can be identified at cross-sectional imaging as pancreatic head tissue partially encircling the second part of duodenum. The configuration of the pancreatic head surrounding the duodenum can be either circular or traingular [1]. The triangular configuration of the annulus characteristically produces a crocodile jaw appearance on axial CT/ MR imaging [1], as is seen in the present case.

Differential Diagnosis List

Final Diagnosis

Partial annular pancreas

URL:	https://www.eurorad.org/case/9547
DOI:	10.1594/EURORAD/CASE.9547
ISSN:	1563-4086