Light-microscopic analysis of sectioned Sézary cells: an accurate alternative to electron microscopy.

The prognostic implications of circulating Sézary cells in mycosis fungoides (MF) are not known, and the significance of fluctuating Sézary cell counts in either MF or the Sézary syndrome has not been assessed. Such studies have been hampered by the inaccuracy of counts performed on routine blood smears and the unavailability of electron microscopy for routine purposes. The present studies conducted on the peripheral blood of 35 patients with either MF or the Sézary syndrome show that Sézary cell counts performed by light microscopy of sectioned Epon-embedded lymphocyte fractions are as accurate as those carried out at the ultrastructural level. In addition, the studies include preliminary observations concerning 20 patients whose Sézary cell counts were repeated over time intervals ranging from 3 months to over 5 years. The described method should facilitate the performance of blood and lymph node Sézary cell counts on a wider scale, which is a necessity if the significance of circulating Sézary cells is to be evaluated.