The diagnosis of cutaneous T-cell lymphoma by morphometric evaluation of the cellular infiltrate, using semithin sections.

In order to improve the cytological criteria for the diagnosis of cutaneous T-cell lymphomas (CTCL), a number of morphometric assessments in semithin sections have been performed on the dermal infiltrates of twenty-one cases of overt CTCL (group I) and twenty-two cases of well-defined benign dermatoses (group II). In each biopsy, an average of 250 cells were measured for perimeter (P), surface area (S), 'nuclear shape index' (NSI), mean surface and mean NSI. We also determined the percentage of typical 'highly cerebriform lymphocytes' (HCL). Cells of group I patients were found to have mean S and mean NSI that differed significantly from those of group II. HCL were found to have a mean NSI value of less than 0.40. The diagnostic value of these measurements was confirmed in the group I patients. Nineteen of them had a mean NSI value of less than 0.61, together with a mean S greater than 14 sq. micron. None of the twenty-two patients of group II had such values. The discriminating power of these criteria was then tested retrospectively on another group of initially controversial patients who presented with suspected CTCL (group III patients). Nine have since evolved into overt CTCL (group III M) while the other ten have remained benign (group III B). All group III B patients and five patients of group III M were correctly assigned using the above morphometric criteria. This method could improve the diagnosis of the early stage of cutaneous T-cell lymphoma.