[Cerebral involvement in the Sézary syndrome (author's transl)].

Two foci of histologically verified mycosis fungoides were found in the left parietal region of a 45-year-old man with involvement of the brain during an exacerbation of leukemia. There was perivascular and diffuse infiltration with lymphoma-like cells and occasional giant (Lutzner) cells but no involvement of the meninges. Both before and after operation the CSF contained a few atypical lymphocytes and mononuclear cells, one of which showed ultrastructurally the deeply clefted nucleus of Sézary cells. Atypical cells were confirmed morphologically in the peripheral blood, as well as by cytochemical (beta-glucuronidase) and immunological (rosettes with SRBC) markers, after the postoperative leucocytosis had subsided. It is suggested that this CNS involvement during a leukemic conversion phase of mycosis fungoides is consistent with the Sézary syndrome.