THE SMALL-CELL VARIANT OF MYCOSIS-FUNGOIDES - A CLINICOPATHOLOGICAL AND QUANTITATIVE ELECTRON-MICROSCOPIC STUDY ON 14 PATIENTS

Small-cell variants of Sezary syndrome and mycosis fungoides (MF) have been described. However, in these studies the nuclear area of the sma ll-cell variant of MF (SC-MF) as compared to histological classical MF (CL-MF) was not characterized objectively by quantitative electron mi croscopy, In a 14-year follow-up period, of a total of 76 patch/plaque stage MF patients seen in the Department of Dermatology of the Univer sity Hospital Utrecht, 14 (18%) had an infiltrate composed of atypical lymphocytes characterized by a distinctly smaller cell diameter and s maller, hyperchromatic, deeply indented nuclei as compared to the usua l cell type of MF. The aim of the investigation was to confirm this ob servation objectively using quantitative electron microscopy (morphome try) and to define SC-ME as compared to CL-MF. The study was performed on the 14 patients with SC-ME and 10 patients with clinical and histo logical CL-ME and 4 patients with chronic eczema. Electron micrographs of sections obtained from each biopsy were analysed by computer to pr oduce the following data: a nuclear contour index (NCI), the mean nucl ear area (MNA), the mean nuclear area of the cells above the 75th perc entile (P75NA) and the percentage of cells larger than 30 mu m(2). The values of MNA differed significantly between patients with SC-ME and those with CL-MF (17.6 vs 23.2 mu m(2); P = 0.02), as did the values o f P75NA (20.7 vs 27.9 mu m(2); P = 0.01), The NCI of the SC-MF and CL- MF patients were similar. These results are consistent with our observ ations that SC-ME does indeed exist.