Perturbation of epidermal Langerhans cells in basal cell carcinomas

Epidermal Langerhans cells (LC) play a pivotal role in a variety of local immune responses. Using ATPase-stained preparations, we evaluated the density and morphologic features of these cells in the skin of 12 patients with basal cell carcinoma (BCC). In three patients, we compared the density of LC in the tumor to that in the perilesional skin. In these cases, there was no difference in the numbers of LC/mm² in the two sites. Perturbations of ATPase-positive, dendritic LC were evident in all specimens. These perturbations included various degrees of disruption of the usually uniform LC network and alterations in the morphology of LC. Many LC had rounded, deformed cell bodies, dendrites that were shortened or completely absent, and variations in the intensity of ATPase staining. With the use of an image analyzer, a measure of the deviation from circularity-a 'dendricity index' (DI) - was obtained, based on the area and perimeter of the LC. A significantly lower DI, implying a predominance of less dendritic, more rounded LC, was observed in LC at the BCC surface than in LC present in perilesional skin. This finding raises the possibility that BCC may arise in areas where the morphology, or activity, of these immune cells has been altered; alternatively, the perturbations could reflect an effect of the tumor cells on LC morphology.