[Adult gastric duplication cyst: diagnosis by endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA)].

Duplication cysts are rare gastrointestinal congenital abnormalities. They can occur anywhere throughout the gastrointestinal tract, and gastric duplication cysts are most uncommon, representing only 4-8% of all gastrointestinal duplication cysts. Nowadays several theories try to explain the pathogenic mechanisms involved. These cysts are usually diagnosed during early childhood, and very rarely are detected in adults, mostly incidentally due to a lack of symptoms. Close to 50% of gastric cysts are associated with other abnormalities. It is extremely important that a meticulous differential diagnosis is performed regarding other diseases, mainly malignancies with a cystic component. Although extremely uncommon, a malignant transformation of these lesions has been reported, which highlights the importance of a correct diagnosis. Herein we report the case of a duplication cyst in an adult, which was detected by endoscopic ultrasound-guided fine-needle aspiration, recently proposed as the most accurate technique for the identification of these lesions.