A 62-year-old man develops scaling and non-scaling patches, and plaques over his chest and back. They are itchy, but not painful. The rest of the examination is normal, except for lymphadenopathy. Examinations of the blood film and skin biopsy histology, both, reveal unusually large monocytoid cells. (See Figure below) Which of the following is the most likely diagnosis?
High-Yield Explanation
These large cells are typical of Sezary syndrome, a leukemic form of cutaneous T-cell lymphoma (CTCL). This is frequently an early presentation of mycosis fungoides or CTCL. There may be a relationship to human T-cell lymphotropic virus (HTLV) I and II, but it is not universal. CTCL is a malignancy of helper T cells (CD4+).