CD38 and Increased total leukocyte count: However, in April 2018, three years following PMF diagnosis and HU treatment, progressive leukocytosis (28 × 109/L) with lymphocytosis (83%) was observed; therefore flow cytometry immunophenotyping of peripheral blood was performed, which showed expression of CD5, CD23, in combination with dim CD20, CD22 and CD43, with dim monoclonal surface immunoglobulin and negative CD38 and CD49b.