Case Report: A rare case of gastric cardia bronchogenic cyst: diagnostic challenges and EUS findings with elevated cyst-fluid tumor markers

Bronchogenic cysts are rare congenital foregut malformations that most commonly occur in the thorax. This case involves a 36-year-old man with abdominal distension who was found to have a cystic lesion adjacent to the gastric cardia. Computed tomography and magnetic resonance imaging revealed a well-circumscribed, non-enhancing cystic mass. Endoscopic ultrasound identified a homogeneous hypoechoic lesion measuring 4.5 × 5.0 cm arising from the muscularis propria layer of the gastric cardia. Fluid analysis obtained by fine-needle aspiration showed elevated tumor markers (CEA, CA19-9, CA125, CYFRA 21-1) and a neutrophil-predominant exudative profile. Cultures for bacteria, fungi, and mycobacteria were negative. Due to the lesion size and uncertain diagnosis, laparoscopic cyst excision was performed. Histopathological examination confirmed a bronchogenic cyst characterized by pseudostratified ciliated columnar epithelium and smooth muscle. The patient recovered without complications and showed no recurrence during one year of follow-up.