Utility and Practicality of Multi-level Sectioning and Upfront Unstained Slide Cutting in Head and Neck Biopsies: A Critical Analysis.

Upfront interval sectioning (cutting unstained slides between H&E levels) is used at our institution for biopsies at all sites except the gastrointestinal tract. Very limited data exists in the literature for the need for interval sectioning, and we are aware of no data at all for the head and neck. Biopsies from the larynx, oral cavity, pharynx, and sinonasal tract at our institution have had 5 levels cut. Levels 1, 3, and 5 or levels 2 and 5 had been stained with hematoxylin and eosin (H&E), depending on the subsite, and the remaining slides saved for possible later use. We retrospectively evaluated the use of unstained slides at these sites for clinical utility and efficiency by analyzing 3 years of cases from 1/1/2014 to 12/30/2016. A cutoff of 10% utilization was considered justification for continued upfront unstained slide cutting. We collected 706 larynx, 572 oral cavity, 184 pharynx, and 85 sinonasal tract biopsies over 3 years. The overall rate of unstained slide usage was 18.2%. Usage rates were significantly different by site: 7.8% (55/706) for larynx, 21.9% (125/572) for oral cavity, 30.6% (26/85) for sinonasal tract and 40.8% (75/184) for pharynx (p < 0.0001). The most common stain ordered in the pharynx was p16 immunohistochemistry (59.7%), but it was Grocott methenamine silver staining in the larynx (74.5%), oral cavity (70.4%), and sinonasal tract (35.1%). Usage of unstained slides was lowest for the larynx, and review of the biopsies with unstained slides utilized showed that the lesion was present on the 3rd H&E level in all cases. Removing this practice would have translated to saving 1,378 unstained slides. Upfront interval sectioning makes practical sense for biopsies from most sites in the head and neck, especially the pharynx, but our data suggests it can reasonably be forgone at least for biopsies of the larynx.