Rare Potential Pitfall in Endoscopic Ultrasound–Guided Fine Needle Aspiration Biopsy in Gastric Duplication Cyst

Abstract

Foregut duplication cyst (FDC) is rare in the adult population. It is usually an incidental finding in clinical settings. As endoscopic ultrasound-guided fine needle aspiration biopsy (EUS-FNAB) becomes a preferred and popular procedure, it is imperative for cytopathologists recognize this rare lesion and avoid the diagnostic pitfall.A 48-year-old man presented with a 3-cm mass on the lesser curvature of the stomach with regional lymphoadenopathy. EUS-FNAB revealed abundant tenacious, viscous, mucinous material with scattered histiocytes and gastric and esophageal mucosal cells. A mucinous neoplasm was suspected, and partial sleeve gastrectomy was subsequently performed for removal of the gastric mass. The histopathologic finding was characteristic of gastric duplication cyst.The cytologic features of FDCs may closely resemble those of mucinous neoplasms, especially with clinically elevated carcinogenic embryonic antigen and CA19-9. The abundant mutinous material with scattered mucophages can create a diagnostic challenge and pitfall. Clinical information with endoscopic findings and knowledge of FDC are important for appropriate diagnosis of mucinous lesions.