Dermoscopy of early stage mycosis fungoides.

BACKGROUND: Early stage mycosis fungoides (MF) is difficult to be clinically differentiated from chronic dermatitis (CD) in a high proportion of patients. Dermoscopy is a rapid, cheep, non-invasive and widely used method for the evaluation of skin tumours and, recently, of inflammatory skin diseases, as well. OBJECTIVE: To describe the dermoscopic pattern of early stage MF and compare it with the dermoscopic features observed in CD. METHODS: This was a retrospective study. Dermoscopic images of lesions that were clinically equivocal between MF and CD were evaluated for the presence of predefined morphologic criteria. Diagnosis had been histopathologically and immunohistochemically confirmed in all cases. Sensitivity, specificity, positive predictive value, and negative predictive value were calculated for predefined dermoscopic criteria in relation to the diagnosis of mycosis fungoides. RESULTS: A total of 67 dermoscopic images were selected for dermoscopic evaluation. Mycosis fungoides lesions exhibited a characteristic dermoscopic pattern consisting of fine short linear vessels (sensitivity 93.7%, specificity 97.1%) and orange-yellowish patchy areas (sensitivity 90.6%, specificity 99.7%). A characteristic vascular structure resembling spermatozoa was also found to be highly specific for the diagnosis of mycosis fungoides. CD was typified by a different dermoscopic pattern, usually consisting of dotted vessels. CONCLUSIONS: These observations provide a first indication that early stage MF exhibits a characteristic dermoscopic pattern which is different from CD. Prospective studies with long term follow-up are needed to determine the value of these dermoscopic criteria in the differentiation between the two entities in the daily routine.

Accuracy of dermoscopic criteria for the diagnosis of psoriasis, dermatitis, lichen planus and pityriasis rosea.

BACKGROUND: Dermoscopy is useful in evaluating skin tumours, but its applicability extends also to the field of inflammatory skin disorders. Plaque psoriasis (PP), dermatitis, lichen planus (LP) and pityriasis rosea (PR) are common inflammatory skin diseases, but little is currently known about their dermoscopic features. OBJECTIVES: To determine and compare the dermoscopic patterns associated with PP, dermatitis, LP and PR and to assess the validity of certain dermoscopic criteria in the diagnosis of PP. METHODS: Patients with PP, dermatitis, LP and PR were prospectively enrolled. The single most recently developed lesion was examined dermoscopically and histopathologically. Variables included vascular morphology, vascular arrangement, background colour, scale colour, scale distribution and presence of Wickham striae. Univariate and adjusted odds ratios were calculated. Discriminant functions were used to plot receiver-operator characteristic curves. RESULTS: Eighty-three patients with PP and 86 patients with either dermatitis, LP or PR were included in the study. Dotted vessels in a regular arrangement over a light red background and white scales were highly predictive for the diagnosis of PP, whereas dermatitis more commonly showed yellow scales and dotted vessels in a patchy arrangement. PR was characterized by yellowish background, dotted vessels and peripheral scales; whitish lines (Wickham striae) were seen exclusively in LP. CONCLUSIONS: PP, LP, PR and dermatitis show specific dermoscopic patterns that may aid their clinical diagnosis. Certain combinations of dermoscopic features can reliably predict the diagnosis of PP.