A dermoscopic study in the diagnosis of plaque psoriasis as compared with contact dermatitis, lichen planus, and pityriasis rosea in Indian patients

Background Dermoscopy is a noninvasive diagnostic tool to visualize clinical patterns of various pigmented skin lesions. Dermoscopy improves the accuracy of the clinical diagnosis of papulosquamous disorders like psoriasis as an additional measure. This in turn avoids the need for invasive diagnostic techniques like skin biopsy. Objective To record the dermoscopic findings in plaque psoriasis (PP), chronic dermatitis (CD), lichen planus (LP), and pityriasis rosea (PR). Patients and methods A case–control study was conducted on 130 patients: 65 patients diagnosed with PP as cases and 65 patients with a diagnosis of CD, LP, and PR as controls. Patients of any age and sex, irrespective of duration of the disease, were included in the study. The single most recently developed lesion of each patient was evaluated with a Heine delta 20 plus dermoscope. Results A combination of regularly distributed dotted vessels over a light-red background associated with diffuse white scales was highly predictive of PP. CD showed similar proportion of patients with patchy and peripheral distribution of scales with a network-like pattern. All the cases of LP revealed Wickham’s striae with a reticulate pattern. White-colored collarette of scaling on a yellow background was characteristic of PR. Conclusion Dermoscopy is emerging as an essential supplement to clinical examination in general dermatology. Visualization of specific dermoscopic features enhances the diagnostic utility of nonpigmented skin disorders. Knowledge of specific dermoscopic patterns can enable a clinician solve diagnostic dilemmas in various papulosquamous diseases.