Stereological study of desmosomes in basal cell carcinoma and seborrheic keratosis.

Desmosomes exhibit quantitative alterations in neoplastic diseases. We used direct and stereological measurements to quantify these structures in basal cell carcinomas and in seborrheic keratoses, in comparison with the basal stratum of normal epidermis. Tissue fragments were processed for electron microscopy. Random sampling procedure was used to obtain micrographs of cells from each of the three groups. The following parameters were calculated: volume of the 'average' cell (Vcell), relative surface area of plasma membrane occupied by desmosomes (Ss), mean desmosome diameter (delta) and mean desmosome surface area (s), number of desmosomes per unit surface area (Ns), mean surface area of plasma membrane (Spm), total surface area (Sdes) and number of desmosomes on the 'average' cell (Ndes). Cell volume to surface ratio (V/S) and volume density of intercellular space (Vvint) were also determined. The parameters Ns, Sdes, and Ndes decreased both in basal cell carcinomas and in seborrheic keratoses. The lowest values were obtained in basal cell carcinomas. Instead, the parameters delta, Ss and Vvint increased in both lesions.