Role of Superficial CD200 Marker in Differential Diagnosis of Malignant B-Cell Lymphoproliferative Diseases

Background & Aims. Flow cytometry is successfully used for diagnosis of malignant lymphoproliferative disorders. However, there are atypical cases that are difficult to interpret; thus, new markers relevant for the differential diagnosis are to be searched for. The aim is to analyze CD200 expression in patients with B-cell lymphoproliferative disorders. Materials & Methods. 187 patients with chronic lymphocytic leukemia (CLL), 14 patients with mantle cell lymphoma (MCL), 9 patients with marginal zone lymphoma (MZL), and 5 patients with hairy cell leukemia (HCL) were enrolled in the study. Neoplasm was not confirmed in 12 subjects. The patients underwent the following tests: CBC, immunophenotyping of peripheral blood or bone marrow lymphocytes, and a cytogenetic test. In some cases, an additional immunohistochemical test of bone marrow trepanobiopsy or lymph node biopsy samples was required. Results. In all cases of CLL and HCL, the CD200 expression was positive; mean fluorescence intensity was higher in these cases as compared to other groups. Negative expression of CD200 prevailed in MCL patients; however, at the same time 2 cases of intermediate and positive expression were reported, both showing moderate fluorescence intensity values. CD200 expression was heterogeneous in MZL patients. Conclusion. The CD200 negative expression excludes typical HCL and CLL. Additional cytogenetic and immunnohistoсhemical tests should be performed in such cases to verify the diagnosis, first of all, MCL or MZL