CD200 expression on Sezary cells: A valuable tool for flow cytometric assessment of peripheral blood T-cell neoplasms

CD200 (OX-2) is a valuable marker in the diagnosis of B-cell neoplasms and is commonly used in the screening panels for assessment of peripheral blood B-cell lymphoproliferative disorders. However, there is limited understanding about CD200 expression in T-cell neoplasms. A previous study has shown that CD200 is expressed on the neoplastic cells of angioimmunoblastic T-cell lymphoma (AITL) by immunohistochemistry, but no study has evaluated CD200 expression in T-cell neoplasms by flow cytometry.We assessed CD200 expression in peripheral blood T-cell lymphoproliferative disorders by retrospective analysis of our institutional flow cytometry screening database over a 6-year period.In addition to AITL, we identified CD200 expression in a significant number of mycosis fungoides/Sezary syndrome cases (58%, 19 of 33 samples), while most other T-cell neoplasms were negative for CD200. These findings were confirmed by CD200 immunohistochemical staining of tissue specimens from our patient cohort.CD200 is commonly expressed on circulating Sezary cells, a feature that can potentially improve the diagnostic value of flow cytometry for assessment of T-cell neoplasms.