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

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.

Objective: 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.

Conclusions: The value of RCM in the diagnosis and differential diagnosis of AK is good and worthy of clinical application.