Use of conventional smears versus liquid‐based preparations for fine‐needle aspirate specimens: The time has not come to abandon your conventional smears!

Abstract

There is a longstanding controversy about the use of conventional smears (CSs) versus liquid-based preparations (LBPs) for thyroid fine-needle aspiration (FNA) specimens, 1-7 and recently, there has been the suggestion that LBPs alone might be a good strategy for all FNAs. This is an unfortunate, and in my opinion, very misguided proposal on multiple levels. Although LBPs have certain redeeming qualities such as reducing the number of slides that the cytologist and cytotechnologist need to evaluate, when used alone for FNA evaluation, they can also reduce the overall amount of cytomorphologic information readily available to the cytopathologist to make a well-informed diagnosis. Use of an LB-only approach, in many instances, is analogous to reading Cliffs Notes instead of the full novel: certainly, it is less material to review but useful information may be missing! A lack of quality FNA sample procurement secondary to poor FNA technique, and a lack of good smear preparation skills, should not be the rationale for adoption of an LB-only approach and abandonment of CSs, but unfortunately, in many cases, it is.The earliest LBPs were developed in the form of the ThinPrep, which was first approved by the US Food and Drug Administration for the evaluation of FNA specimens in 1991. 1 Proponents of LBPs list as their advantages the ease of preparation without learning smearing techniques and the reduction in background blood and debris. I will mention that the Cytopathology Division where I practice uses CSs sometimes in combination with a single LBP from the rinsings for many of our FNA specimens, but we avoid using LBPs alone for FNAs. I consider myself fortunate to have this advantage at my institution. Having ample experience with both CSs and with LBPs, I view the LB-only strategy to FNA as a significant diagnostic disadvantage. Even laboratories that use only LBPs for thyroid FNAs, typically do not carry this approach over to other FNA specimens.Conventional smears, either alcohol-fixed and Papanicolaou-stained or air-dried and Romanowsky stained, have been the mainstay of FNA evaluation for many decades, 1,8 and it is for good reason that they have withstood the test of time. In FNAs from various anatomic sites including the thyroid gland, salivary glands, breast, lung, and soft tissues, advantages of CSs include the maintenance of the relative cellularity of the specimen and maintenance of the quantitities of background material such as colloid, mucin, matrix, stromal elements, or necrotic debris. CSs also preserve the cytoarchitectural integrity of the tissue as reflected in the arrangement of cells in medium-to large-size groups. These are all features which are irrefutably key to the