Kidney Transplant Modifies the Architecture and Microenvironment of Basal Cell Carcinomas

Background/Aims: Basal cell carcinoma (BCC) is a frequent type of nonmelanoma skin cancer, which shows a greater prevalence in kidney-transplanted (KT) patients than in the general population. The study of this tumor in KT patients may allow us to understand the influence of the tumor inflammatory microenvironment on cancer behavior, and to design new image analysis methods to determine prognosis and apply personalized medicine. The major hypothesis of the present work is that antirejection drugs, by modifying the B-cell/T-cell balance, induce measurable differences in tumoral cell microarchitecture and in the inflammatory microenvironment in KT patients compared to nontransplanted controls. Methods: In this retrospective study in an Italian cohort including 15 KT patients and 15 control subjects from the general population who developed BCC, we analyzed tissue microarchitecture and inflammatory infiltrates of BCC using state-of-the-art nonlinear image analysis techniques such as fractal dimension and sample entropy of internuclear distances. Results: KT patients showed a nonsignificant trend to a greater number of nuclei in the basal cell layer compared to non-KT controls and subtle changes in the intact skin compared to controls. Similarly, the number of mitoses per unit length was almost doubled in the patients with KT compared to controls. However, when the number of mitotic cells was normalized by the total number of cells in the basal layer (mitotic index), these differences were not significant, although a clear trend was still present. Finally, KT patients showed a nonsignificant trend to an increased ­density of inflammatory cells close to the tumoral cell layer. When considering the intact skin, this difference was significant, with a 70% increase in the density of inflammatory cells. Conclusion: Data comparing the microarchitecture of BCC in normal subjects and KT patients are scanty, and the present study is the first to use nonlinear image analysis techniques to this aim. The observed differences underscore the relevance of T-cell suppression in cancer behavior. These data suggest that BCC develops in treated patients with specific biological characteristics which should be further analyzed in terms of therapeutic response.