A rare case of combined annular pancreas and duodenal adenocarcinoma

Abstract

Annular pancreas is a rare congenital anomaly consisting of a partial or complete ring of pancreatic tissue encircling the second part of the duodenum. The encircling tissue is continuous with the head of the pancreas and may include a pancreatic duct. The true incidence is not well established and is estimated to be 3 in 20 000. Annular pancreas is diagnosed equally in children and adults. The diagnosis in children is often suggested prenatally by neonatal ultrasound and confirmed within the first 1–2 days of life. Adults present with pain and gastrointestinal symptoms including nausea, vomiting and abdominal bloating. Childhood cases are frequently associated with congenital anomalies whereas adults show an increased risk of pancreatobiliary neoplasia. We present a Whip-ple’s resection of an annular pancreas associated with duodenal adenocarcinoma in a 63-year-old male, a rarely reported combination. The second part of the duodenum was thickened by not only the circumferential tumour mass but also a variably thick rim of pancreatic tissue containing an aberrant pancreatic duct. The macroscopic evaluation of this specimen was challenging and in the absence of a cancer, the duodenum thickened by an annular pancreas could potentially be mistaken for a tumour mass.