Ultrastructure of abnormal cells in Sezary syndrome, mycosis fungoides, and parapsoriasis en plaque

A cell with characteristic ultrastructural features was found in tissues from all six Sezary patients studied. This cell has a highly irregular, serpentine nucleus, which in three-dimensional reconstruction appears to be cerebriform and composed of highly folded sheets. Abnormal cells were also found in tissues from 34 of 38 patients with mycosis fungoides (MF). The nuclei of these MF cells were also irregular, but less so than Sezary cell nuclei. These MF cells were also found in six of eight patients with parapsoriasis en plaque. In order to determine the diagnostic specificity of these abnormal MF cells, skin from 33 control patients with a variety of malignant and benign skin diseases was studied. Cells similar to MF cells were found in skin from three of these control patients; so, it appears that the presence of this unusual cell is not absolutely specific for the diagnosis of MF.