en Dermatology Dermatology Original Research Original Research <strong>&nbsp;&nbsp;</strong><strong>&nbsp; Background: </strong>Skin biometrology is a useful method for evaluation of inflammatory skin disorders such as dermatitis, psoriasis, and lichen planus. The current study tries to compare the biophysical features of skin in dermatitis, psoriasis, and lichen planus.<br> <strong>&nbsp;&nbsp; Methods:</strong> By a convenient sampling method, 22 mild to moderate chronic dermatitis, 26 psoriasis, and 21 lichen planus patients were recruited in the study. Stratum corneum (S.C.) hydration, Transepidermal water loss (TEWL), pH, erythema, melanin, sebum, friction, elasticity parameters (R0, R2, and R5), skin temperature, skin thickness, and echo-density of epidermis and dermis were measured on the lesional (selected active lesion), uninvolved perilesional, and uninvolved symmetrical skin. The average of perilesional and symmetrical uninvolved parameters was used as control, while the percentage change of each parameter [(lesion &ndash; control / control) &times;100] was calculated, and compared among three diseases by ANOVA test using SPSS software version 18. The significance level was set at &alpha;=0.05.<br> <strong>&nbsp;&nbsp; Results:</strong> Comparison of percentage changes showed that the changes in TEWL, friction index, sebum content, R2 (gross elasticity), R5 (net elasticity), skin temperature, dermal thickness, and epidermal density are not significantly different among three skin diseases. But there were significant differences in three diseases considering the decrease in S.C. hydration (p<0.001), R0 (opposed to firmness) (p<0.001), and dermal density (p<0.001) compared to control skin. Moreover, the increase in skin pH (p<0.001), melanin content (p=0.048), erythema (p=0.023), and epidermal thickness (p <0.001) significantly differed among these diseases.<br> <strong>&nbsp;&nbsp; Conclusion:</strong> Dermatitis, psoriasis and lichen planus lesions had specific biophysical changes. It may be helpful in their differential diagnosis.<br> &nbsp; Biophysical properties, Dermatitis, Lichen planus, Psoriasis, Ultrasonographic properties 630 634 http://mjiri.iums.ac.ir/browse.php?a_code=A-10-3847-1&slc_lang=en&sid=1 Taraneh Yazdanparast drtaraneh@yahoo.com 200319475328460042032 200319475328460042032 No Center for Research and Training in Skin Diseases and Leprosy, Tehran University of Medical Sciences & Telemedicine Research Center, National Research Institute of Tuberculosis and Lung Diseases (NRITLD), Shahid Beheshti University of Medical Sciences, Tehran, Iran Kamran Yazdani kyazdani48@yahoo.com 200319475328460042033 200319475328460042033 No Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Philippe Humbert philippe.humbert@univ-fcomte.fr 200319475328460042034 200319475328460042034 No Centre d’Etudeset de Recherchesur le Tégument (CERT), INSERM UMR1098, SFR FED 4234 IBCT, University of Franche-Comté, Besançon, France Alireza Khatami alirezakhatami1970@yahoo.com 200319475328460042035 200319475328460042035 No Center for Research and Training in Skin Diseases and Leprosy, Tehran University of Medical Sciences, Tehran, Iran Saman Ahmad Nasrollahi samannasrol@gmail.com 200319475328460042036 200319475328460042036 No Center for Research and Training in Skin Diseases and Leprosy, Tehran University of Medical Sciences, Tehran, Iran Hournaz Hassanzadeh hasanzadeh.hoornaz92@gmail.com 200319475328460042037 200319475328460042037 No Center for Research and Training in Skin Diseases and Leprosy, Tehran University of Medical Sciences, Tehran, Iran Amir Houshang Ehsani ehsanih@tums.ac.ir 200319475328460042038 200319475328460042038 No Department of Dermatology, Razi Hospital, Tehran University of Medical Sciences, Tehran, Iran Leila Izadi Firouzabadi lilaizadi@yahoo.com 200319475328460042039 200319475328460042039 No Department of Dermatology, Razi Hospital, Tehran University of Medical Sciences, Tehran, Iran Alireza Firooz alifiruz@yahoo.com 200319475328460042040 200319475328460042040 Yes Center for Research and Training in Skin Diseases and Leprosy, Tehran University of Medical Sciences & Clinical Trial Center, Tehran University of Medical Science, Tehran, Iran