Noninvasive Imaging Techniques for the Diagnosis of Nonmelanoma Skin Cancers

Nonmelanoma skin cancers (NMSC), basal cell carcinoma (BCC), and cutaneous squamous cell carcinoma (cSCC) are the most common neoplasms worldwide. Their incidence has been continually rising. This is due to several risk factors such as chronic sun exposure, longer life expectancy, sun-damaged skin, genetic predisposition, and immunosuppression. NMSCs are curable cancers if detected early and treated appropriately. Clinical examination is the first step towards their diagnosis, with accuracy depending on clinician expertise. Dermoscopy has become an irreplaceable diagnostic procedure for clinical examination and improving diagnostic accuracy of skin cancers. However, skin biopsy with histopathological analysis remains the gold standard in establishing a definite diagnosis. Repeated biopsies, however, are not acceptable in patients with multiple suspicious lesions and are often redundant in cases of lesions that are challenging to identify, as they are often benign. Several medical imaging technologies are available as additional tools for noninvasive examination of NMSCs and include reflectance confocal microscopy (RCM), high-frequency ultrasound (HFUS), optical coherence tomography (OCT), Raman spectroscopy, fluorescence polarization, and others. These methods enable clinicians to establish more rapid and accurate diagnoses without the need for invasive biopsies and to achieve optimal treatment for NMSC. RCM an HFUS are discussed along with their clinical applications.