Evaluation of dermatoscopic criteria for early detection of squamous cell carcinoma arising on an actinic keratosis

Background: Advanced squamous cell carcinoma (SCC) can be discriminated easily from actinic keratosis (AK) based on clinical and dermatoscopic features. However, at the initial stage of dermal invasion, SCC might still be clinically flat and discrimination from AK remains challenging, even with the addition of dermatoscopy. Objective: The aim of this study was to investigate the clinical and dermatoscopic criteria that could suggest early invasion and serve as potent predictors to discriminate early SCC from AK. Methods: Clinical and dermatoscopic images of histopathologically diagnosed AKs and early SCCs were evaluated for the presence of predefined criteria by 3 independent investigators. Results: A total of 50 early SCCs and 45 AKs were included. The main positive dermatoscopic predictors of early SCC were dotted/glomerular vessels (odds ratio [OR] 3.83), hairpin vessels (OR 12.12), and white structureless areas (OR 3.58), whereas background erythema represented a negative SCC predictor (OR 0.22). Limitations: The retrospective evaluation of images. Moreover, the differential diagnosis included in the study is restricted between AK and early SCC. Conclusions: We identified potent predictors for the discrimination of AK and early SCC that may better guide management decisions in everyday clinical practice.