Clear cell basal cell epithelioma: light and electron microscopic study of an unusual variant.

We report the light and electron microscopic study of 7 examples of an unusual clear cell variant of basal cell epithelioma (BCE). The clear cells show cytoplasmic vacuoles that contain glycogen but do not stain with mucicarmine or fat stains. By electron microscopy the cytoplasmic vacuoles consist of empty spaces not surrounded by membranes. The clear cell pattern may occupy all or part of a given tumor. Typical nodular BCE was found in all 7 cases, but not in every section. Some nodules were composed of mixed solid and clear cell types. Differentiation of this uncommon variant from other clear cell tumors is important.