Ultrastructural morphometry in the diagnosis of Sézary syndrome.

Blood specimens from 87 patients and control subjects were prepared for electron microscopy and subjected to ultrastructural morphometric evaluation by using a computerized planimeter. A statistical comparison of means indicated that patients with Sézary syndrome could be distinguished from normal subjects and patients with reactive lymphocytosis, by using mean nuclear perimeter and form factor values. The lymphocytic nuclei from patients with infectious mononucleosis were more lobated on visual inspection than those from normal subjects; the difference in mean form factor values was statistically significant. The simple histogram method was most discriminatory and distinguished patients with Sézary syndrome from patients with other types of lymphoid leukemias and reactive lymphocytosis, including infectious mononucleosis. The histogram method could not, however, distinguish patients with Sézary syndrome from patients with T-cell chronic lymphocytic leukemia and Japanese T-cell leukemia. The use of bivariate graphic displays (plotting nuclear size and shape measurements) placed the lymphoid cells of the various types of lymphoproliferative disorders into distinct morphometric domains. Computerized morphometric techniques may, therefore, be of greater value when the range of possible diagnoses is large.