Basal cell carcinoma: Comprehensive clinical and histopathological aspects, novel imaging tools and therapeutic approaches (Review)

Basal cell carcinoma (BCC) is one of the most common malignant tumors worldwide, involving the skin. It is also part of keratinocyte carcinomas, alongside its squamous counterpart. It has low mortality and extremely low metastatic rates (although when present, it indicates a poor patient prognosis); it also has a high morbidity rate through local destruction and recurrence, particularly when perineural invasion is observed, clinically or histopathologically. BCC development is the result of environmental and patient factors, with genetics and ultraviolet radiation playing major roles. The clinical and histopathological aspects vary according to tumor subtype, being classified as high-risk tumors (nodular, superficial, pigmented and infundibulocystic BCC with adnexal differentiation) and fibroepithelial subtypes, or as high-risk tumors (micronodular, infiltrating, sclerosing/morphoeic and basosquamous subtype or the type with sarcomatoid differentiation). Dermoscopy is now complimented by novel <i>in vivo</i> diagnostic tools (optical coherence tomography, reflectance confocal microscopy, high-resolution ultrasonography, Raman spectroscopy or terahertz pulse imaging), improving the diagnostic accuracy and providing tumor depth and lateral margins without the use of invasive techniques. Novel treatment approaches for the treatment of BCC have recently been investigated with the use of hedgehog pathway inhibitors, such as Vismodegib. These approaches aim for complete resolution, minimal side-effects, high patient satisfaction with the optimal cosmetic results, particularly in key areas, such as the face. The present review article summarizes and discusses the comprehensive clinical and histopathological aspects of BCC, and presents novel imaging tools and therapeutic approaches that have been identified.