Diagnostic yield and agreement on fine-needle specimens from solid pancreatic lesions: comparing the smear technique to liquid-based cytology

Abstract

<b>Background and study aims</b> 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). <b>Patients and methods </b> 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. <b>Results </b> Diagnostic accuracy for malignancy was higher for LBC (82 % (58/71)) than for smear (66 % (47/71), <i>P</i> = 0.04), but did not differ when smears were compared to ThinPrep (71 % (30/42), <i>P</i> = 0.56) or Cell block (62 % (39/63), <i>P</i> = 0.61) individually. Artifacts were less often present in ThinPrep (57 % (24/42), <i>P</i> = 0.02) or Cell block samples (40 % (25/63), <i>P</i> < 0.001) than smears (76 % (54/71)). Agreement on malignancy was equally good for smears and LBC (ĸ = 0.71 versus ĸ = 0.70, <i>P</i> = 0.98), but lower for ThinPrep (ĸ = 0.26, <i>P</i> = 0.01) than smears. <b>Conclusion </b> 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.