TY - JOUR T1 - Evaluation of an innovative new method for quantitation of plasma cells on CD138 immunohistochemistry JF - Journal of Clinical Pathology JO - J Clin Pathol DO - 10.1136/jclinpath-2021-207828 SP - jclinpath-2021-207828 AU - Ethan Gantana AU - Nomusa Mashigo AU - Ibtisam Abdullah AU - Ernest Musekwa AU - Robert Lohlun AU - Erica-Mari Nell AU - Carissa Chetty AU - Monalisa Ntobongwana AU - Zivanai Chapanduka Y1 - 2021/10/05 UR - http://jcp.bmj.com/content/early/2021/10/08/jclinpath-2021-207828.abstract N2 - Aim To compare the frequently used CD138 immunohistochemistry-based method of plasma cell quantitation, to a proposed new method, using interobserver and intraobserver concordance parameters.Methods Archival CD138 immunohistochemically stained slides made from paraffin-embedded bone marrow biopsies of 33 patients with a confirmed diagnosis of multiple myeloma were used. Light microscopic examination was performed using low magnification lenses (10×) for both the overview estimation method (method A) and the new method (method B), and high magnification lenses (50×), for method B only. For method B, reviewers selected three areas with low, intermediate and high plasma cell densities using 10× lenses. Using a well-defined technique, the 50× lens was then used to count plasma cells as a percentage of all nucleated cells. After blinded relabelling of all the slides, the nine reviewers repeated the plasma cell quantitation using both methods. The plasma cell counts were obtained, and the review times were recorded.Results Overall intraobserver concordance was comparable for method A (concordance correlation coefficient (CCC)=0.840) and method B (CCC=0.733). Interobserver concordance for method A (intraclass correlation coefficient (ICC)=0.793 and 0.713) and method B (ICC=0.657 and 0.658) indicated high similarity between reviewers. Method A showed poor interobserver concordance (ICC=0.105) at low plasma cell densities.Conclusions The new method is comparable to the frequently used overview estimation method in terms of intraobserver and interobserver concordance, and cost. The new method has superior interobserver concordance at low plasma cell densities. The new method appears more amenable to digital scanning and analysis.All data relevant to the study are included in the article or uploaded as supplemental information. ER -