Duplication cyst of the pancreatic duct presenting as pancreatitis

Background: Enteric duplication cysts involving the pancreas are exceedingly rare. They may easily be mistaken for an inflammatory pseudocyst or choledochal cyst so careful interpretation of imaging studies and thorough evaluation, which may include an ERCP, are necessary. Clinical Vignette: We present an 11-year old white male with chronic diffuse abdominal pain that did not radiate to the back or flanks, and no associated nausea, vomiting, diarrhea, or fever. He had no history of abdominal trauma or alcohol abuse, and had not been on any medications. Past medical history was notable for a right thoracotomy during the first two weeks of life to remove a right posterior mediastinal cystic mass, not contiguous with the gastrointestinal tract, that appeared intraoperatively to be an esophageal duplication cyst. Pathology disclosed a mature teratoma. Physical examination revealed a well-appearing male with a soft, non-tender abdomen. He had no organomegaly, rebound tenderness or guarding. The rest of the examination was normal. Laboratory tests were normal except for elevated amylase (638 U/L) and lipase(515 U/L) levels. CT of the abdomen revealed a 4cm × 5cm × 11cm cystic mass thought to be an inflammatory pseudocyst, which remained unchanged after two weeks of therapy for pancreatitis. A choledochal cyst was ruled out after a HIDA scan failed to show uptake of dye by the cyst. An ERCP disclosed a 2.5cm × 10cm fusiform cyst lateral to the pancreas emanating from the pancreatic duct, and compressing the biliary system. At surgery, an accesory pancreatic duct was identified. Biopsy of the cyst wall revealed mucus epithelium. The patient was diagnosed with benign congenital duplication cyst of the pancreas. Roux-Y-cystojejunostomy was performed to drain the cyst because the cyst was too adherent to the porta hepatis and head of the pancreas to allow for complete excision. He had an uneventful recovery with resolution of the cyst. Conclusion: Duplication cysts of the pancreas result from failure of an enteric diverticulum of the pancreatic duct to regress. Although they rarely give rise to symptoms, sufficiently large cysts may result in pancreatitis, as in our patient.