Clinical differentiation between pityriasis lichenoides chronica (PLC) and guttate psoriasis (GP) may sometimes be a difficult task, which often requires histological analysis to reach a definitive diagnosis. In this study, PLC and GP lesions were examined using dermoscopy, and the significance of specific dermoscopic findings was investigated in order to facilitate their differentiation and decrease the number of cases requiring biopsy. We found that the incidence of orange-yellowish structureless areas, focal dotted vessels and nondotted vessels was statistically significant in PLC, while the incidence of diffuse dotted vessels was statistically significant in GP.

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The diagnosis of prurigo nodularis is mainly clinical, based on its distinctive features. However, in some cases it may be difficult to differentiate it from other nodular dermatoses only on the clinical basis, thus requiring histopathological examination to reach a definitive diagnosis. The aim of this study was to describe for the first time the dermoscopic features of prurigo nodularis and the useful contribution of dermoscopy in the differential diagnosis of such dermatoses. Fourteen patients with histopathologically proven prurigo nodularis were included in the study. The results of our study suggest that the detection of a "white starburst pattern" surrounding brown-reddish/brown-yellowish crust(s), erosion(s) and/or hyperkeratosis/scales is a useful clue to support the clinical diagnosis of prurigo nodularis, distinguishing it from the other main differential diagnoses.

Background Psoriasis (Ps) is a chronic systemic autoimmune disease associated with pruritus in 64–98% of patients. However, few modestly sized studies assess factors associated with psoriatic pruritus. Objective To investigate factors associated with Ps pruritus intensity. Methods Psoriasis patients 18 years or older seen in one of 155 centres in Italy between September 2005 and 2009 were identified from the Italian PsoCare registry. Patients without cutaneous psoriasis and those with missed information on pruritus were excluded. Results We identified 10 802 patients, with a mean age 48.8 ± 14.3 years. Mild itch was present in 33.2% of patients, moderate in 34.4%, severe in 18.7% and very severe in 13.7%. Higher itch intensity was associated with female gender, lower educational attainment compared to university degree, pustular psoriasis, psoriasis on the head, face, palmoplantar areas, folds and genitalia, more severe disease, disease duration <15 years, and no or few prior systemic treatments. Limitations Effects of specific medication on itch were not assessed. Conclusions Pruritus should be evaluated during psoriasis visits, and physicians should be aware of patients at higher risk for itch. Further studies are needed to assess the effects of medications on itch, and establish therapy for psoriasis patients with persistent itch.

Differentiation between psoriatic arthritis (PsA) sine psoriasis and rheumatoid arthritis (RA) may be a challenge, especially in the early stages, hence the need for new instrumental markers to assist their diagnosis. In this study, we investigated possible dermoscopic differences in vascular appearance of nail fold and elbow (a classic site of repeated trauma) in these two conditions. Fifteen patients with PsA sine psoriasis, 12 patients with RA and 12 controls were included in the study. Regarding the nail fold vascular appearance in PsA sine psoriasis and RA cohorts, the presence of diffuse reddish background with or without sparse dotted vessels was significant in the former, whereas the evidence of parallel dotted/short linear vessels (“fish school‐like” pattern) or irregular/ramified, blurry, purple vessels were significant in the latter; none of these patterns were detected in the control group. Regarding the elbow, the pattern significantly associated with PsA sine psoriasis consisted of diffusely distributed, red, dotted vessels. On the other hand, RA patients and controls displayed similar dermoscopic findings, with three possible vascular patterns being observed: (i) irregular, blurry, purple vessels; (ii) avascular appearance; and (iii) sparse, dotted, purple vessels. In conclusion, dermoscopy may be a useful supportive tool for differentiating early PsA sine psoriasis from RA.