Gastric duplication cyst: a challenging EUS differential diagnosis between subepithelial gastric lesion and exophytic pancreatic cystic neoplasm-a case report and a literature review.

Gastric duplication cysts are rare congenital malformation with a potential neoplastic progression and they may represent a challenge in differential diagnosis with exophytic pancreatic cyst neoplasm. We describe a case of a 38-year old man, complaining of recurrent epigastric pain due to a large abdominal mass, referred to our Hospital for EUS evaluation. Differential diagnosis was between gastric duplication cyst and exophytic pancreatic cyst because of FNA pointed out amylase 1280 UI/L and CEA 593.33 ng/mL. Despite antibiotic prophylaxis, an overinfection of the lesion occurred after the FNA, likely due to the technical failure to drain the cyst completely. Afterwards, the patient was referred to surgery and the pathologist confirmed the diagnosis of gastric duplication cyst. In this setting, EUS procedure has gained a leading play, complementary to traditional imaging tests, although its role has been not yet standardized in the reported literature. Here, we describe and discuss our demanding case, and we propose an algorithm to simplify and standardize the diagnostic workup.