Background and study aims: The traditional “smear technique” for processing and assessing endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) is sensitive to artifacts. Processing and evaluation of specimens collected in a liquid medium, liquid-based cytology (LBC) may be a solution. We compared the diagnostic value of EUS-FNA smears to LBC in pancreatic solid lesions in the absence of rapid on-site evaluation (ROSE).
Patients and methods: Consecutive patients who required EUS-FNA of a solid pancreatic lesion were included in seven hospitals in the Netherlands and followed for at least 12 months. Specimens from the first pass were split into two smears and a vial for LBC (using ThinPrep and/or Cell block). Smear and LBC were compared in terms of diagnostic accuracy for malignancy, sample quality, and diagnostic agreement between three cytopathologists.
Results: Diagnostic accuracy for malignancy was higher for LBC (82% (58/71)) than for smear (66% (47/71), P=0.04), but did not differ when smears were compared to ThinPrep (71% (30/42), P=0.56) or Cell block (62% (39/63), P=0.61) individually. Artifacts were less often present in ThinPrep (57% (24/42), P=0.02) or Cell block samples (40% (25/63), P<0.001) than smears (76% (54/71)). Agreement on malignancy was equally good for smears and LBC (ĸ=0.71 versus ĸ=0.70, P=0.98), but lower for ThinPrep (ĸ=0.26, P=0.01) than smears.
Conclusion: After a single pass, LBC provides higher diagnostic accuracy than the conventional smear technique for EUS-FNA of solid pancreatic lesions in the absence of ROSE. Therefore, LBC, may be an alternative to the conventional smear technique, especially in centers lacking ROSE.