Epidermal Langerhans cells in mycosis fungoides and Sézary syndrome.

The purpose of the study was to examine whether apposition between epidermal Langerhans cells and atypical lymphoid cells is a constant finding in mycosis fungoides (MF) and whether it also occurs in the Sézary syndrome (SS). Biopsies of 8 patients with MF and 2 patients with SS were examined by transmission electron microscopy. In both cases of SS and in 7 cases of MF appositions between the 2 types of cells were observed. The appositions were less frequently seen in stage III MF lesions than in MF stage II. The cell membranes of the Langerhans cells and the apposed atypical lymphoid cells formed gap junction-like structures in several instances. Our results indicate that the phenomenon of cellular interaction between epidermal Langerhans cells and atypical lymphoid cells is a constant finding in cutaneous T-cell lymphomas.