Experimental dermatology • Concise report CED Clinical and Experimental Dermatology Differentiation of pityriasis lichenoides chronica from guttate psoriasis by dermoscopy E. Errichetti, 1 F. Lacarrubba, 2 G. Micali, 2 A. Piccirillo 3 and G. Stinco 1 1 Department of Experimental and Clinical Medicine, Institute of Dermatology, University of Udine, Italy; 2 Dermatology Clinic, University of Catania, Italy; and 3 SOC Dermatologia e Malattie Sessualmente Trasmesse, San Carlo Hospital, Potenza, Italy doi:10.1111/ced.12580 Summary Clinical differentiation between pityriasis lichenoides chronica (PLC) and guttate pso- riasis (GP) may sometimes be a difficult task, which often requires histological analy- sis to reach a definitive diagnosis. In this study, PLC and GP lesions were examined using dermoscopy, and the significance of specific dermoscopic findings was investi- gated 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. The clinical differentiation of pityriasis lichenoides chronica (PLC) and guttate psoriasis (GP) may some- times be a diagnostic challenge; in such cases, histo- pathological examination helps to differentiate the two conditions. Recently, the application of dermoscopy has also been extended to inflammatory skin disorders in order to assist the clinical diagnosis and decrease the number of cases requiring biopsy. 1,2 In this study, PLC and GP lesions were examined using dermoscopy, and the significance of specific dermoscopic findings was investigated. Report The study was approved by institutional review board of Udine University, and all patients provided written informed consent. This was a cross-sectional study that enrolled eight patients (five men, three women; mean age, 39.1  15.1 years) with biopsy-proven PLC and nine patients (six men, three women; mean age, 33.4  14.5 years) with biopsy-proven GP. One dermoscopic image taken of a target lesion from each patient using a manual dermoscope (Heine Delta 20 â 9 10; Heine Optotechchnik, Herrsching, Germany) equipped with a camera (Coolpix â 4500 Nikon Corpo- ration, Melville, NY, USA) was retrospectively reviewed by an independent dermoscopist not aware of the his- tological diagnosis. Statistical analysis was performed using Stata soft- ware (v12; StataCorp 2011, College Station, TX, USA), and the Fisher exact test (results were considered sta- tistically significant at P < 0.010). Seven patients (87.5%) with PLC had trunk involve- ment, four (50.0%) had involvement of the lower extremities and three (37.5%) had involvement of the lower extremities, while the figures for patients with GP were nine (100.0%), five (55.6%) and three (33.3%), respectively. The specific dermoscopic findings of PLC and GP are summarized in Table 1. We found that the most com- mon dermatoscopic features of PLC (present in seven of the eight cases; 87.5%) were orange–yellowish struc- tureless areas and nondotted vessels (including milky- red areas/globules, linear irregular and branching ves- sels). Focally distributed dotted vessels were observed in five patients (62.5%), while hypopigmented areas were evident in only one case (Fig. 1a). Dermoscopy of GP lesions revealed in all patients a monomorphic picture quite similar to that commonly found in plaque Correspondence: Dr Giuseppe Stinco, Institute of Dermatology, University of Udine, Ospedale ‘San Michele’ di Gemona, Piazza Rodolone 1, 33013, Gemona del Friuli, Udine, Italy E-mail: giuseppe.stinco@uniud.it Conflict of interest: the authors declare that they have no conflicts of interest. Accepted for publication 12 August 2014 Clinical and Experimental Dermatology 1 ª 2015 British Association of Dermatologists