Dermoscopy Useful in Differentiating Features of Common Skin Diseases

Dermoscopy is a useful tool for differentiating conditions among common inflammatory and infectious dermatoses, which can minimize unnecessary invasive diagnostic procedures. These are among the study findings published in Clinical, Cosmetic and Investigational Dermatology.

Researchers conducted a cross-sectional study at a dermatology clinic of a major hospital in Bangkok, Thailand, between September 2016 and December 2020. Eligible patients had presented to the hospital with rash of the body, face, or trunk and received a preliminary diagnosis of an inflammatory or infectious skin condition.

Participants’ most recently developed lesion underwent dermoscopic evaluation. Dermoscopic images were evaluated separately by a blinded dermatologist and evaluated using a correlation matrix. Biopsies were taken from lesions for a definitive diagnosis.

A total of 102 participants (mean age, 51.8±17.3 years; 55.9% women) were included in the study. Histopathological diagnosis identified dermatitis in 43 participants (42.3%); psoriasis in 30 (29.5%); lichen planus in 14 (13.7%); pityriasis rosea in 5 (4.9%); dermatophytosis in 3 (2.9%); secondary syphilis in 2 (1.9%); lichen striatus in 2 (1.9%); dermatomyositis in 2 (1.9%); and pityriasis rubra pilaris in 1 (1.0%).

Dermoscopy features positively correlated with dermatitis included a dull red background (r, 0.401), patchy vessels (r, 0.488), and scales (r, 0.327) (P <.01). Psoriasis was strongly associated with bright red background (r, 0.412), glomerular vessels (r, 0.266), regular vascular distribution (r, 0.798), and diffuse scales (r, 0.401) (P <.001). Lichen planus was associated with whitish reticulate structures, purplish background, and dotted vessels mixed with linear vessels in the peripheral distribution. Yellowish background and peripheral scales were predictive of a diagnosis of pityriasis rosea. The remaining diagnoses had too few patients to be included in the correlation matrix.

Limitations of the study include the small study cohort and the absence of data on disease severity.

“Our study highlights the utility of dermoscopic examination as an adjunctive tool to distinguish conditions among common inflammatory and infectious dermatoses presenting with erythematous plaque(s) with or without scales in order to minimize unnecessary invasive investigative procedures,” the researchers conclude.