Dermoscopy And Reflectance Confocal Microscopy In The Diagnosis Of Inflammatory Dermatoses

Background:Dermoscopy and Reflectance Confocal Microscopy(RCM)as non-invasive tools have been widely used in inflammatory skin diseases.Dermoscopy can visualize the features of blood vessels,including vascular morphology and vascular distribution,etc.Therefore,dermoscopy are gaining increasing importance in the diagnosis of inflammatory skin disorders.RCM as a reproducible imaging technique can carry out real-time and dynamic scanning imaging of skin structures by different refrective index of tissue cells,thus assisting in the diagnosis of skin diseases in current clinical practice.Objectives:Few studies have directly compared the diagnostic accuracy of dermoscopy and RCM for inflammatory skin diseases.The purpose of this study was to calculate and compare the accuracy of dermoscopy and RCM in the diagnosis of psoriasis,lichen planus,and chronic eczema,and to assess the specific criteria of dermoscopy and RCM features in these dermatoses.Methods:We retrospectively collected clinical,dermoscopy,and RCM images of psoriasis,dermatitis,pityriasis rosea and lichen planus cases with definite histomathological diagnosis in China-Japan Friendship Hospital from March 2018 to February 2021.The 10 experts evaluated the dermoscopy and RCM images without knowing the clinical images or the histomathological diagnosis,indicating the most likely diagnosis and whether the diagnosis was confirmed.They also needed to indicate the quality of each image and whether specific dermoscopy or RCM pattern existed.We calculated the diagnostic sensitivity,specificity,positive predictive value and negative predictive value for each and all investigaters using dermoscopy and RCM in the diagnosis of these diseases.By analyzing the Receiver Operator Characteristic Curve(ROC Curve),we evaluated and compared the diagnostic accuracy of dermoscopy and RCM in these inflammatory skin diseases.We calculated the percentage of images of high quality and the percentage of images showing specific dermoscopic or RCM patterns,and also assess the interobserver consistency by calculating Fleiss Kappa values.In this study,SPSS statistical software 26.0 and MedCalc statistical software 19.0 were used for statistical analysis,and p value<0.05 on both sides was considered to be statistically significant.Results:We collected 207 inflammatory dermatoses cases,including 82 psoriasis,47 lichen planus,and 78 eczema.Dermatoscopy had higher sensitivity and negative predictive value than RCM in the diagnosis of psoriasis,and AUC comparison suggested that dermatoscopy had better diagnostic accuracy than RCM(0.879 vs.0.835,p=0.0001).For lichen planus,RCM had higher sensitivity,positive predictive value and negative predictive value than dermoscopy,and AUC comparison suggested that RCM had better diagnostic accuracy than dermoscopy(0.916 vs.0.813,p<0.0001).Both dermoscopy and RCM had high specificity and negative predictive value for eczema,but there was no statistically significant difference between them.Moreover,both of them had relatively low sensitivity and positive predictive value for eczema.AUC comparison suggested that RCM had better diagnostic accuracy than dermoscopy(0.787 vs.0.759,p=0.0353).The most typical feature of psoriasis under dermoscopy was evenly distributed dotted vessels,while in eczema the dotted vessels were mainly focally distributed.The most specific manifestation of lichen planus under dermoscopy was Wickham Striae(65.3%±2.7%),with strong consistency among observers.The most typical manifestations of psoriasis under RCM were Munro microabscess(66.1%±3.2%),and of lichen planus were interface dermatitis(86.0%±4.6%),which were both strongly consistent among observers.However,there was no significant difference in the detection of inflammatory cells in dermis between psoriasis and eczema.Conclusions:Dermatoscopy and RCM play a significant role in assisting the diagnosis of psoriasis,lichens planus and eczema.These two non-invasive 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.