Dermoscopic clues to diagnose some papulosquamous skin diseases

Background Papulosquamous skin diseases (PSDs) are commonly encountered inflammatory dermatoses and are frequently misdiagnosed. Histopathology is the cornerstone for definite diagnosis of misleading cases, but dermoscopy might be a helpful advantageous tool for distinguishing these entities. Objective To study the dermoscopic features of some common PSDs [psoriasis (Ps), lichen planus (LP), seborrheic dermatitis (SD), and pityriasis rosea (PR)] in relation to their histopathologic features and to assess the usefulness of dermoscopy in their diagnosis. Patients and methods A total of 60 patients with classic presentation of common PSDs who were diagnosed clinically were included (20 patients with Ps, 18 with LP, 10 with SD, and 12 patients with PR). Dermoscopic examinations and digital photography were done for all cases, and then skin biopsies were obtained for haematoxylin and eosin histopathologic evaluation. Results The included PSDs revealed different specific dermoscopic patterns. Ps was characterized by the combination of diffuse white scales and regularly distributed dotted vessels over either a light or dull red background. LP was characterized by the combination ofWickham’s striae (white crossing streaks) and peripheral dotted vessels over a violet or red background. SD was characterized by the presence of yellow scales and dotted vessels in a patchy distribution over a light red background, whereas PR was characterized by the presence of peripherally arranged white scales with a patchy distribution of dotted vessels over a yellowish background. These different specific dermoscopic patterns were well related to their corresponding histopathological features (P 0.05 for all). Conclusion Dermoscopy could be considered a safe and rapid diagnostic tool that assists the clinical diagnosis and differentiation of frequently encountered PSD, and it could minimize the need for invasive skin biopsies with satisfactory reflection of the corresponding structure histopathologic alterations.