Density of dendritic cells around basal cell carcinomas is related to tumor size, anatomical site and stromal characteristics, and might be responsible for the response to topical therapy.

Background: The dermal dendritic cell (DC) is considered to be an important component of the host defense against basal cell carcinomas (BCCs). Imiquimod, an immunologic response modifier, has recently been introduced in the topical therapy of BCCs. There is some evidence that the DC pretreatment density may affect the efficacy of imiquimod. The aim of our study was to find out which clinical or histological variables are related to the DC density at the margins of BCCs.

Methods: Thirty cases of BCCs of aggressive and 30 cases of nonaggressive subtypes were selected from our files. In histological sections, the density of FXIIIa-positive DCs and 1A4-positive myofibroblasts in the tumor surrounding stroma was quantified, as well as the stroma type, the tumor size and the DC density in the normal dermis.

Results: In nonaggressive BBCs, a multiple linear regression showed that a higher DC density was associated with an increased number of myofibroblasts, smaller tumors and those located on the face. For the aggressive subtypes, a higher DC density was related not only to an increased myofibroblast density, smaller BCCs or location on the face, but also to the presence of less mucinous and more granulation type stroma and an increased DC density in the normal dermis. The stability of the models was confirmed by bootstrap resampling.

Conclusion: Our study demonstrates that the density of DCs around BCCs is related to tumor size, localization and characteristics of the surrounding tumor stroma.