Gastric Duplication Cyst: A Rare Congenital Disease Often Misdiagnosed in Adults

Gastrointestinal duplication is a rare congenital disease which affected more commonly the ileum, while the stomach is rarely involved. Generally diagnosed in paediatric or young age, it could be difficult to suspect a gastrointestinal duplication in adults. Herein, we report a 55-year-old male with a gastric duplication cyst found on routinely checkup for chronic hepatitis and first misdiagnosed as a gastrointestinal stromal tumor (GIST); we also discuss its embryology. 1. Introduction Gastrointestinal duplication is a rare congenital disease defined as a spherical hallow structure with a smooth muscle coat, lined by a mucus membrane and attached to any part of the gastrointestinal tract from the base of the tongue to the anus; because these malformations are formed before differentiation of the lining epithelium, they are named for the organs with which they are associated [1]. Most common involved sites are ileum followed, in order of frequency, by oesophagus, jejunum, stomach, and colon [2]. Gastric duplication cysts are very uncommon with a reported incidence of 4%–8% among all gastrointestinal duplication cysts [3]. Herein, we report a gastric duplication cyst in a 55-year-old man first misdiagnosed as a gastrointestinal stromal tumor (GIST) and discuss its embryological origin. 2. Case Presentation A 55-year-old man suffering from B type chronic hepatitis treated with antiretroviral drugs was found to have a hypoechoic round-shaped mass sized 4.7？cm, with regular margins, during an abdominal ultrasonography performed for scheduled checkup. The mass was located between the left liver lobe and the anterior surface of the pancreatic body. The patient did not complain of any symptoms about gastrointestinal tract. To better evaluate the mass, patient underwent MR imaging that confirmed the presence of a cystic mass with complex content located forward to the gastroesophageal junction. A subsequently endoscopic ultrasonography showed a hypoechoic mass with a slightly heterogeneous internal echo and regular margins located just below the gastroesophageal junction; the lesion measured about 4.5？cm and seemed to be contiguous to the fourth wall layer (muscularis propria) (Figure 1). Figure 1: Endoscopic ultrasonography showing a hypoechoic mass with a slightly heterogeneous internal echo and regular margins located just below the gastroesophageal junction. On the basis of a diagnosis suspicious for GIST involving the upper part of the gastric wall, a diagnostic confirmation through an EUS-guided fine needle aspiration with a 22？G needle was taken; it was