Histomorphologic, immunohistochemical and molecular validation of 2.5-hour processed large specimens/tumor resections with tissue-tek xpress x120
Zarbo R, Schmidt M, Althaver N, Whiteley L, Gupta N, Chitale D, and Goerke D. Histomorphologic, immunohistochemical and molecular validation of 2.5-hour processed large specimens/tumor resections with tissue-tek xpress x120. Modern Pathology 2020; 33(3):1685.
Background: We seek to shorten histology preanalytic time to meet pathology reporting needs of 16 weekly specialty Tumor Boards in the precision medicine oncology program of the Henry Ford Cancer Institute. Design: We validated an extended 2.5-hour microwave and vacuum-assisted processing cycle (Tissue-Tek Xpress x120, Sakura Finetek USA, Torrance, CA) for large specimens/tumor resections compared to our 5.5-10 hour microwave process (Logos, Milestone, Kalamazoo, MI). Specimens were collected from operating rooms of Henry Ford Hospital, dissected fresh at 2-3mm thickness into mirror images and fixed in 10% neutral buffered formalin, minimum 6, maximum 72 hours. Xpress bench processing step post formalin fixation was 30 minutes of isopropranol-based pre-processing solution for water/formalin extraction followed by 2 hours of Xpress processor time composed of 2 x 30-minute microwave temperature controlled isopropyl alcohol and acetone based dehydration/xylene-free clearing retorts and 2 x 30-minute heated paraffin impregnation retorts using vacuum. Blocks from both Xpress and Logos pathways were cut and stained together to minimize inter-run variation. 3 pathologists assessed slides for histomorphology (188 tumor and 67 normal tissues), and 24 selected tumors in a tissue microarray (TMA) (2 cores from each tumor: 10 lung, 10 colon, 4 renal cell) for immunohistochemical (IHC) staining with 22 antibodies and molecular validation of DNA/RNA quality and next generation sequencing (NGS) assay using TruSeq Amplicon 48-gene Cancer Panel (Illumina, San Diego, CA). Results: All tissues were equivalent for histologic interpretation. There were no differences in IHC profiles of TMA tissues for PAX5, PAX8, CD45, CD3, CD10, CD20, TTF-1, Napsin A, CK5/6, CK7, cytokeratins AE1/AE3, CAM 5.2, p63, p40, EMA, vimentin, carbonic anhydrase IX, AMACR, CDX2, Ki67, and beta catenin. DNA/RNA quality between the 2 processors was comparable (Table 1a, 1b) as was quality of DNA/RNA purity and amplicon fragment length (200, 300, 400 bp). There was good correlation between % uniformity of coverage, but poor for depth of coverage. All samples passed NGS quality matrix criteria for reporting variants and no differences in hot spot mutations were detected (Table 2). (Figure presented) Conclusions: This validated Xpress processor for large specimens/tumor resections will reduce current technical process time by 55-75% and promotes our goal of continuous laboratory production flow to meet the demand for faster surgical pathology diagnostic reporting.