The ultrastructure of mycosis fungoides, of Sezary's syndrome, and of Woringer-Kolopp's disease (pagetoid reticulosis).

Skin lesions of 13 cases of mycosis fungoides, 2 cases of Sézary's syndrome and one case of Woringer-Kolopp's disease were studied. In mycosis fungoides two main cell types were observed: small atypical lymphoid cells, and large atypical lymphoid cells. The small atypical lymphoid cells were characterized by dense nuclei with varying degrees of nuclear lobulation. Normal-appearing lymphocytes and typical mycosis cells were in this cell group. The large atypical lymphoid cells were characterized by large nuclei with little lobulation and by less chromatin condensation, as well as by a more abundant cytoplasm. Their identification is discussed and indications of their possibly being neoplastic or proliferating lymphoblasts are given. In Sézary's syndrome Sézary cells with more lobulated nuclei than in mycosis cells and lymphoblast-like cells as in mycosis fungoides could be found. In Woringer-Kolopp's disease cells similar to Sézary cells aggregated mainly in the epidermis. No interdigitating reticulum cells and no other morphological signs of a specific lymphocyte microenvironment were found in any of the cases.