Laser-induced fluorescence made simple: implications for the diagnosis and follow-up monitoring of basal cell carcinoma.

Noninvasive treatments are increasingly being used for the management of basal cell carcinoma (BCC), the predominant type of nonmelanoma skin cancer, making the development of noninvasive diagnostic technologies highly relevant for clinical practice. Laser-induced fluorescence (LIF) spectroscopy emerges as an attractive diagnostic technique for the diagnosis and demarcation of BCC due to its noninvasiveness, high sensitivity, real-time measurements, and user-friendly methodology. LIF relies on the principle of differential fluorescence emission between abnormal and normal skin tissues (ex vivo and in vivo) in response to excitation by a specific wavelength of light. Fluorescence originates either from endogenous fluorophores (autofluorescence) or from exogenously administered fluorophores (photosensitizers). The measured optical properties and fluorophore contributions of normal skin and BCC are significantly different from each other and correlate well with tissue histology. Photodynamic diagnosis (PDD) is based on the visualization of a fluorophore, with the ability to accumulate in tumor tissue, by the use of fluorescence imaging. PDD may be used for detecting subclinical disease, determining surgical margins, and following-up patients for residual tumor or BCC relapse. In this review, we will present the basic principles of LIF and discuss its uses for the diagnosis, management, and follow-up of BCC.