[Roles of dermoscopy in differential diagnosis of psoriasis and eczema]

To describe the dermoscopic patterns of plaque psoriasis and chronic eczema and explore the roles of dermoscopy in their diagnosis and differential diagnosis.

A total of 68 patients with plaque psoriasis or chronic eczema were recruited from our department from December 2013 to May 2014 to undergo dermoscopic and histopathological examinations. Dermoscopic features of vascular morphology, vascular arrangement, background color, scale color and scale distribution were evaluated. Sensitivity, specificity, positive predictive value and negative predictive value were calculated for predefined dermoscopic criteria in relation to the diagnosis of plaque psoriasis.

Thirty-one patients with plaque psoriasis and 37 patients with chronic eczema were included. Dotted vessels in a regular arrangement (sensitivity 80.6%, specificity 73.0%) over a light red background (sensitivity 71.0%, specificity 75.7%) and white scales (sensitivity 71.0%, specificity 83.8%) were highly predictive for the diagnosis of plaque psoriasis. And chronic eczema more commonly showed yellow scales and dotted vessels in a patchy arrangement over a dull red background. Characteristic vascular structures of hairpin vessels and red loops were also found to be highly specific (91.9%, 94.6%) for the diagnosis of psoriasis.

Plaque psoriasis shows specific dermoscopic patterns compared with chronic eczema. And dermoscopy is valuable in the diagnosis and differential diagnosis of psoriasis.