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

Abstract

BACKGROUND: 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. CASE: 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. CONCLUSION: 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.