BACKGROUND Despite many reports on the diagnostic yield of cytology from endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA), inter-slide differences are unknown. This prospective study aimed to compare diagnostic yield and cellular characteristics of bottom slides (BS) and top slides (TS) from EUS-FNA cytology performed without an on-site cytopathologist.

METHODS In patients with suspected pancreatic cancer on previous imaging explorations, a single endoscopist performed EUS-FNA and obtained 2 sets of cytology slide (8 BS and 8 TS), 1 cellblock slide, and 1 biopsy slide. Both slide sets were randomly assigned. A cytopathologist with more than 10 years of expertise in pancreatic cytopathology blindly inspected and compared two slide sets.

RESULTS In total, 73 specimens [42 head (57.5%), 16 body (21.9%), and 15 tail (20.5%)] were acquired for final analysis. Seventy-one cases were finally diagnosed with pancreatic cancer. The sensitivity and specificity of BS were 80.3% and 100.0%; and of TS 78.9% and 100.0%, respectively. In analyzing inter-slide difference, 66 cases (90.4%) showed consistent results between BS and TS. However, seven (9.6%) were positive only in one slide sets (4 BS and 3 TS). The proportions of specimens more than moderate and high cellularity were 75.3% and 60.3% in both slide sets (P> 0.99), and the proportion of artifact-free sets were 50.7%, and 52.1% for the BS and TS, respectively (P= 0.869).

CONCLUSIONS Although BS and TS exhibited highly consistent diagnostic yields in cytologic smears from EUS-FNA, the proportion of inter-slide discordance is clinically considerable. Both slide sets need to be examined if there is no on-site cytopathologist.