PMC5948470_01
A. Circulating atypical lymphocytes with irregular nuclear contours in the peripheral blood. 1B. Slightly increased interstitial CD3+ T-cells in the bone marrow biopsy (CD3 immunohistochemical stain, x100). 1C. Skin biopsy showing superficial dermal atypical lymphocytic infiltrate (H&E stain, x200). 1D. The dermal atypical lymphocytes are mainly CD4+ cells (CD4 immunohistochemical stain, x200). 1E. Flow cytometry performed on the peripheral blood showed an atypical CD4+ T-cell population, which decreased CD3 expression, dim CD7 and loss of CD26.
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Peripheral blood flow cytometry revealed cytologically and phenotypically atypical lymphocytes (Fig. 1A), which prompted additional work up. Subsequent bone marrow biopsy revealed atypical lymphocytic infiltrate cytologically and phenotypically consistent with mature CD4+ T-cells with decreased expression of CD2, CD3, dim to loss of CD7, loss of CD26 and elevated CD4:CD8 ratio of 19.4 (Fig. 1B, E). T-cells with CD4:CD8 ratio >10:1 (Fig. 1C, D). These findings met diagnostic criteria of Sezary syndrome.