Dermoscopic characterization of guttate psoriasis, pityriasis rosea, and pityriasis lichenoides chronica in dark skin phototypes: An observational study.

Dermoscopy as a diagnostic tool is attaining impetus in inflammatory dermatoses with the cumulative description of characteristic findings in most dermatoses obviating at times the need of biopsy. In this retrospective observational study, 20 histopathology confirmed cases each of pityriasis rosea (PR), guttate psoriasis (GP), and pityriasis lichenoides chronica (PLC) seen over a period of 3 years were included. Dermoscopy images were extracted from photography archives for evaluation and three lesions from each patient (60 lesions each) were analyzed. Comparison of dermoscopy characters was done among PR, GP, and PLC in pairs using chi-square test and a P-value of less than .05 was considered significant. Most common background color in PR (86.7%) and PLC (96.7%) was yellow to yellow-orange and in GP was dull red to pink (70%). Vessels were visualized in all lesions of GP and most characteristic pattern was regular (93.3%), dotted vessels (95%). In PR 63.3% lesions had dotted vessels mostly in a patchy distribution (56.7%). Most prominent scale color in PR was yellow-white (88.3%) and in GP was white-gray (80%). In PLC varying colors were seen, most prominent being brown (53.3%). Characteristic findings seen only in PLC were hypopigmented areas (13.3%), brown dots and globules (53.3%) and orange-yellow structureless areas (61.7%) GP, PR, and PLC reveal specific dermoscopic findings that can help in differentiating them. Further, the known dermoscopic criteria for GP, PR, and PLC also apply for dark skin phototypes.

Dermoscopy in differential diagnosis of inflammatory dermatoses and mycosis fungoides.

BACKGROUND: The use of dermoscopy for the evaluation of various inflammatory dermatoses has witnessed a gradual increase in recent years. The present study describes and highlights the importance of dermoscopic findings in the differential diagnosis of plaque psoriasis (PP), lichen planus (LP), mycosis fungoides (MF), pityriasis rosea (PR), and nummular dermatitis (ND) that mostly involve the trunk. METHODS: The study included 150 cases (PP:50, LP:30, MF:20, PR:30, ND:20). The lesions were inspected using a polarized dermoscope. The dermoscopic findings of each lesion were evaluated for background color, type, and distribution of vessels, color and distribution of scales, and other additional findings. RESULTS: When the patient groups were evaluated for background color, yellow color was prominent in PR, and light and dull red color was prominent in other groups. Dotted vessels were prominent in PP, PR, and ND, and dotted + linear vessels were significantly more prominent in MF and LP. In the evaluation of the distribution pattern of vessels, PP showed regular, LP showed peripheral, and PR, MF, and ND showed patchy distribution patterns. White scales were prominent in PP, PR, and MF, and yellow-white scales were prominent in LP and ND. Only PR had a predominant peripheral distribution of scales, while other groups had a patchy distribution. CONCLUSIONS: In conclusion, it was observed that PP, LP, MF, PR, and ND exhibited specific dermoscopic patterns that might be useful in clinical diagnosis.