Gastric duplication cyst or pancreatic pseudocyst: a diagnostic dilemma

Gastric duplication cysts (GDCs) are rare congenital anomalies that can closely resemble other cystic abdominal lesions, particularly pancreatic pseudocysts. We present the case of a 4-year-old girl with progressive abdominal distension, pain, and elevated serum amylase levels. Initial imaging including an abdominal ultrasound, contrast-enhanced computed tomography, and endoscopic ultrasound, suggested a pancreatic pseudocyst, resulting in an endoscopic cystogastrostomy and stent placement. However, post-procedure magnetic resonance cholangiopancreatography revealed a thick-walled cyst with an inner mucosal lining, raising suspicion for a GDC. Surgical excision confirmed the diagnosis, and the patient had an uneventful recovery. This case highlights the diagnostic challenge of differentiating GDCs from pancreatic pseudocysts due to overlapping clinical and imaging features.