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 lm 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.

Introduction Literature data on dermoscopic features of psoriasis vulgaris are inconsistent. The aim of the study was to evaluate whether dermoscopic features of psoriatic plaques differ with anatomic location or any clinical characteristics. Materials and Methods Clinical evaluation and videodermoscopy of psoriatic plaques located on the face, chest, abdomen, forearms, lower legs, back, and scalp were performed in 50 patients with psoriasis vulgaris. Results A total of 306 plaques were evaluated. Videodermoscopy with a 20‐fold magnification revealed red dots and globules in 306/306 (100%) plaques, arranged in diffuse (170/306, 56%), patchy (117/306, 38%), or polygonal (19/306, 6%) pattern. A 70 fold magnification of these vessels revealed the presence of bushy vessels (213/306, 70%) and twisted loops (107/306, 35%), with the latter occurring more commonly on the scalp and face (P < .001). In lesions lasting less or equal 5 weeks on forearms and scalp, patchy distribution of the scale predominated, whereas in older lesions—diffuse type (forearm P = .005, scalp P = .017). Diffuse distribution of the scale in lesions located on the face was more common in women, than men (P = .003). Conclusions Videodermoscopic picture of psoriatic plaques may differ with the anatomic location and duration of the psoriatic plaque and with patient's sex.

BackgroundThe diagnosis of a patient with erythroderma may be difficult and sometimes pose a challenge for both dermatologist and pathologist. The role of dermoscopy in this area seems to be poorly investigated. There are only a few reports, with limited number of patients, describing dermoscopic features in erythroderma of various origins. To the best of our knowledge, none of the previous studies had included trichoscopic examination.ObjectivesAnalysis of dermoscopic and trichoscopic patterns in series of patients with erythroderma.MethodsWe retrospectively analysed 28 adult patients who presented with erythroderma between May 2016 and August 2020. Demographic data, disease course and duration, previous treatment, as well as dermoscopic and trichoscopic features were analysed.ResultsThere were 9 patients (32.1%) with the diagnosis of mycosis fungoides, 8 patients (28.5%) with atopic dermatitis, 3 patients (10.5%) with Sézary syndrome and 3 patients (10.5%) with pityriasis rubra pilaris. The others were diagnosed with allergic eczema (n = 1; 3.6%), dermatomyositis sine myositis (n = 1; 3.6%), psoriasis (n = 1; 3.6%), actinic reticuloid (n = 1; 3.6%) and crusted scabies (n = 1; 3.6%). Characteristic dermoscopic/trichoscopic patterns have been observed in erythroderma due to crusted scabies, psoriasis, dermatomyositis sine myositis, Sézary syndrome and pityriasis rubra pilaris. Differentiation of mycosis fungoides and long‐standing atopic dermatitis based on dermoscopy is difficult, as the overlap of vessel morphology, background colour and scale colour exists. Similarly, differentiation between AD and AE based on dermoscopy/trichoscopy seems to be impossible, and clinical background is crucial.ConclusionDermoscopy and trichoscopy seem to provide additional clues in the assessment of erythrodermic patient. Depending on the underlying cause, trichoscopy or dermoscopy may be more useful.

There is a paucity of data concerning the usefulness of trichoscopy in patients with erythroderma. The aim of the study was to compare the trichoscopic features in erythroderma of various aetiologies. In total, 49 patients with a determined cause of erythroderma [including atopic dermatitis (AD), mycosis fungoides (MF), allergic contact eczema (ACE), psoriasis (Pso), S ezary syndrome (SS), drug reaction, pityriasis rubra pilaris (PRP), dermatomyositis (DM), actinic reticuloid (AR), crusted scabies (CS) and pemphigus foliaceus (PF)] were included in the study. Dotted vessels were present in patients with AD, PRP, MF, SS and Pso, and absent in DM, CS and PF (v², P < 0.02). Spermatozoon-like vessels were observed only in MF and SS (P = 0.001). Whitish-pinkish structureless areas were described in all patients with DM, AR and CS (P < 0.03). The type of vessel and the presence of whitish-pinkish structureless areas under trichoscopy may indicate the cause of erythroderma.

<b><i>Background:</i></b> The common inflammatory scalp diseases, such as psoriasis, seborrheic dermatitis, lichen planopilaris, discoid lupus erythematosus, contact dermatitis, or pemphigus may share similar clinical features. <b><i>Objective:</i></b> To identify and systematically review the available evidence on the accuracy of trichoscopy in inflammatory scalp disorders. <b><i>Methods:</i></b> A systematic review was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A total of 58 articles were included in the analysis. <b><i>Results:</i></b> The following trichoscopy features were found to show the highest specificity for the respective diseases: in psoriasis: diffuse scaling, simple and twisted red loops, red dots and globules, and glomerular vessels; in seborrheic dermatitis: atypical vessels, thin arborizing vessels, and structureless red areas; in discoid lupus erythematosus: follicular plugs and erythema encircling follicles; in lichen planopilaris: milky red areas or fibrotic patches; in contact dermatitis: twisted red loops; in pemphigus foliaceus: white polygonal structures and serpentine vessels; in pemphigus vulgaris: red dots with whitish halo and lace-like vessels; and in dermatomyositis: lake-like vascular structures. <b><i>Limitations:</i></b> Different nomenclature and variability in parameters, which were analyzed in different studies. <b><i>Conclusion:</i></b> This systemic analysis indicates that trichoscopy may be used with high accuracy in the differential diagnosis of inflammatory scalp diseases.

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