Dermoscopic features of psoriasis of the skin, scalp and nails - a systematic review.

Dermoscopy is a non-invasive in-office method, which enables the diagnosis of many dermatoses and reduces the need for performing biopsies. To date, no systematic review about the diagnostic usability of dermoscopy in psoriasis has been available. The objective of this article was to summarize and critically analyse literature data on the dermoscopy of skin, scalp and nail changes in psoriasis. A systematic search of three medical databases was performed. A total of 45 articles were included into the analysis. Cutaneous psoriatic lesions assessed in all studies at a low magnification showed regularly distributed red dots. At a 50-fold or higher magnification capillary bushes (glomerular vessels) with a diameter range of 50-146 μm were observed. The background colour was described as reddish or pinkish with white or yellowish scales. The most frequent dermoscopic (trichoscopic) feature of scalp psoriasis was the presence of red dots/globules and twisted red loops. Typical dermoscopic (onychoscopic) signs of nail psoriasis were onycholysis, salmon patches and splinter haemorrhages. There is an accumulating body of evidence that dermoscopy (both handheld and videodermoscopy) is a useful tool in differential diagnosis in doubtful cases of psoriasis of the skin, scalp, nails, palms, soles and genital regions.