How to Prepare, Handle, Read, and Improve EUS-FNA and Fine-Needle Biopsy for Solid Pancreatic Lesions: the Pathologist's Role.

Endoscopic ultrasound (EUS)-guided tissue sampling is a well-established method to accurately diagnose pancreatic lesions. The accuracy of fine-needle aspiration (FNA) and fine-needle biopsy (FNB) is influenced by several factors, including the operator's skill, target lesion characteristics, sampling equipment and technique, tissue handling and processing, and the experience of the pathologist. Importantly, EUS-guided tissue sampling practices vary substantially within the international endosonographic community, and there are no common guidelines for handling samples. A recent international survey showed that the approach to sample handling is highly variable, including tissue processing and rapid on-site pathological evaluation (ROSE).[1] As a result, the diagnostic accuracy among institutions is still highly variable; most highly experienced institutions report a sensitivity of 80% or more.[2,3,4] It must be noted that technological research efforts in this field primarily focus on improvement of the material, design, and size of sampling devices to provide material for histological rather than cytological analysis. However, cytological tissue handling procedures have recently undergone limited developments for thin preparations (liquid-based cytology [LBC]). Importantly, he cellblock techniques are proposed as an adjunct or an alternative to conventional smears. The implementation of these methods requires an additional, although limited, investment in laboratory infrastructure and specific training for cytotechnologists and pathologists for accurate interpretation. Adequate preparation of FNA and FNB samples and dedicated training of cytotechnologists and pathologists are the prerequisites for achieving optimal results.