Comparison of dermoscopy and reflectance confocal microscopy accuracy for the diagnosis of psoriasis and lichen planus

Background Dermoscopy and reflectance confocal microscopy (RCM) as noninvasive tools are gaining increasing importance in the diagnosis of inflammatory skin disorders. The purpose of our study was to calculate and compare the diagnostic accuracy of dermoscopy and RCM in common inflammatory skin diseases. Materials and Methods We retrospectively collected clinical, dermoscopic, and RCM images of psoriasis and lichen planuscases from March 2018 to February 2021 in China-Japan Friendship Hospital. There were 10 experts evaluated dermoscopic and RCM images independently. Sensitivity, specificity, positive predict value, and negative predictive value for each and all investigators were calculated. The diagnostic accuracy was also measured by the area under the curve (AUC) for the Receiver Operator Characteristic (ROC) Curves. Results We collected 82 psoriasis and 47 lichen planus cases. Dermoscopy was more sensitive than RCM in the diagnosis of psoriasis, and overall diagnostic accuracy of dermoscopy was also higher than RCM measured by AUC (0.879 vs. 0.835, p = 0.0001). For lichen planus, RCM had higher sensitivity, specificity, positive predictive value, negative predictive value, and overall diagnostic accuracy than dermoscopy (AUC 0.916 vs. 0.813, p<0.0001). Conclusion Dermoscopy and RCM play a significant role in assisting the diagnosis of psoriasis and lichens planus. These two noninvasive diagnostic tools have their own advantages and disadvantages for the evaluation of different inflammatory skin diseases, and they can be combined in clinical practice to improve the accuracy of the diagnosis of inflammatory skin diseases.