The diagnostic value of in vivo reflectance confocal microscopy in actinic keratosis

Abstract Background Actinic keratosis (AK) is a pre‐neoplastic skin damage caused by sun exposure with a risk of transforming squamous cell carcinoma (SCC) ranging from 0.1%‐20%, while it should be differentiated with many diseases such as seborrheic keratosis (SK), discoid lupus erythematosus (DLE), Bowen's disease, and basal cell carcinoma(BCC) et al. Reflectance confocal microscopy (RCM) as a non‐invasive method is showing an increasing diagnostic accuracy. Currently, there are a few studies that summarized the characteristics of AK with RCM. Aim The study aimed to find the diagnostic value of diagnosing actinic keratosis by reflectance confocal microscopy. Methods A total of 92 patients with clinical suspicious diagnosis of actinic keratosis were enrolled in this study, and RCM device imaged their lesions. Fifty‐three of these patients underwent skin biopsies to confirm the diagnosis. We retrospectively analyzed the results of RCM and histological diagnosis and then summarized the RCM characteristics of biopsy‐confirmed lesions. Results Based on RCM images, 76 of 92 (82.6%) patients were diagnosed with AK, 9 of 92 (9.8%) patients could not be diagnosed by the dermatologist according to RCM. Of all 53 biopsied lesions, 42 (79.2%) were AK, 1 was seborrheic keratosis, 3 were basal cell carcinoma, three were discoid lupus erythematosus, 1 was Bowen's disease, and three were squamous cell carcinoma. Conclusion The value of RCM in the diagnosis and differential diagnosis of AK is good and worthy of clinical application.