Gastric Duplication Cyst

Gastric duplication cyst is a rare congenital cystic malformation lined by gastric or other gastrointestinal mucosa, with a smooth muscle wall shared with the stomach. Most do not communicate with the stomach lumen.

Gastric duplications are 2% to 4% of all alimentary tract duplications. Most are diagnosed in childhood, but adult cases are found incidentally or after complications. There is a mild female predominance.

The usual location is along the greater curvature, within or against the gastric wall, and less often the lesser curvature or pylorus.

Complications are pain, bleeding or ulceration (ectopic gastric mucosa), obstruction, infection, perforation, pancreatitis from compression of the pancreatic duct and, rarely, adenocarcinoma.

Pathophysiology.

Proposed mechanisms include aberrant recanalisation of the solid gut stage, partial twinning and persistent embryonic diverticula. The cyst wall contains smooth muscle and secretes mucus.

Often asymptomatic. Features include epigastric pain, vomiting, early satiety, palpable mass, haematemesis, anaemia and recurrent pancreatitis.

Red flags.

• Peritonitis or fever (perforation or infection).
• Gastrointestinal bleeding.
• Obstructive jaundice or pancreatitis.

Endoscopic ultrasound shows an anechoic or hypoechoic cyst with a five layer wall (inner hyperechoic mucosa and outer hypoechoic muscle), and lacking septation. CT and MRI show a thin walled, non-enhancing cystic mass contiguous with the stomach. Cyst fluid sampling is avoided unless the diagnosis is in doubt, because of infection risk.

Differential diagnosis.

• Pancreatic pseudocyst or cystic neoplasm.
• Gastric stromal tumour with cystic change.
• Hydatid cyst.
• Splenic or adrenal cyst.
• Lymphangioma.

Excise symptomatic and complicated cysts, and also most asymptomatic cysts in children and young adults because of complication and malignancy risk. Laparoscopic excision is usual, with partial gastrectomy when the cyst shares the wall. Endoscopic marsupialisation or resection suits selected cysts near the lumen.

• Cefazolin (surgical prophylaxis): 2 g IV (3 g if over 120 kg) within 60 minutes before incision; single dose, repeated after 4 hours if surgery continues; maximum 6 g in 24 hours for prophylaxis; monitor for hypersensitivity; adjust the interval when creatinine clearance is under 35 mL/min.

Send the specimen for histology to exclude dysplasia.

Monitoring. Clinical review and ultrasound at 3 to 6 months after excision.

Referral and escalation. Paediatric or upper gastrointestinal surgery; advanced endoscopy for endoscopic options.