Kibar M, et al. Ann Dermatol. 2014 Aug;26(4):478-484. http://dx.doi.org/10.5021/ad.2014.26.4.478

Background: Psoriasis and seborrheic dermatitis are both chronic erythemato-squamous dermatoses that can involve the scalp. It may be difficult to differentiate these two diseases when there is isolated scalp involvement. Recently, trichoscopy is commonly used to differentiate noncicatricial alopecias including psoriasis and seborrheic dermatitis that can lead to telogen effluvium (TE). Objectives: The objective of this study is to evaluate the trichoscopic figures that may help to differentiate scalp psoriasis and seborrheic dermatitis. Materials and Methods: Thirty one with scalp psoriasis and 112 patients with seborrheic dermatitis were enrolled. Trichoscopic examinations were performed using a videodermatoscope (MoleMax 3 ^® ). Trichoscopic findings of scalp psoriasis and seborrheic dermatitis were compared with each other, with 100 healthy individuals and with other noncicatricial alopecias including female androgenetic alopecia (FAGA) (n: 138), male androgenetic alopecia (n: 63), FAGA of male pattern (FAGA.M) (n: 5), alopecia areata (39), TE (n: 22) and trichotillomania (n: 4). Results: Atypical red vessels, red dots and globules (RDG), signet ring vessels (SRV), structureless red areas and hidden hairs (HH) were statistically more common in psoriasis while twisted red loops and comma vessels (CV) in seborrheic dermatitis. RDG were considered as the characteristic videodermatoscopic figure for psoriasis and arborizing red lines and CV for seborrheic dermatitis. In comparison with previous reports, our study yielded two new trichoscopic structures supporting the diagnosis of psoriasis; HH and SRV. Besides, according to our study, CV were described for the first time in seborrheic dermatitis and considered to be specific for seborrheic dermatitis. Conclusion: This study confirmed that trichoscopy might be useful in differentiating scalp psoriasis and seborrheic dermatitis from each other and from other noncicatricial alopecia with three trichoscopic structures as HH, SRV and CV.

OBJECTIVE: Differential diagnosis of mycosis fungoides (MF) in the early stages can be challenging. Dermoscopy has been reported to be useful in the evaluation of early MF. However, to our knowledge, there is no study that specifies these early stages as stage IA, IB or IIA. The present study aims to evaluate the dermoscopic findings of stage IIA MF in comparison with plaque psoriasis (PP). METHOS: Thirty-four patients aged between 16-70 years with stage IIA MF (n=17) and PP (n=17) were evaluated in this prospective study. Dermoscopic examinations were performed by manual dermatoscopy (Dermlite DL4). chi(2) test was used. RESULTS: In patients with stage IIA MF, orange-yellow patches (88.2%), short, fine and linear vessels (82.3%), geometric white scales (70.5%), perifollicular white scales (47%) and white patches (35.2%) were common, while dotted vessels (94.1%), diffuse lamellar white scales (88.2%) and dotted and globular vessels (70.5%) were common in patients with PP. Although spermatozoa-like structures, purpuric dots, collarette white scales and Y-shaped arborizing vessels were common in patients with MF, this was not statistically significant. Geometric white scales (clinically; cigarette paper-like wrinkly scales) correlated with alternating parakeratosis and orthokeratosis in the stratum corneum histopathologically. CONCLUSION: A unique aspect of our study is that this study provides insights about the importance of scales in differentiating MF from PP. Orange-yellow and white patches, short, fine and linear vessels, geometric and perifollicular white scales may be useful in distinguishing stage IIA MF from PP by hand-held dermoscopy.