Dermoscopic Features of Psoriasis, Lichen Planus, and Pityriasis Rosea in Patients With Skin Type IV and Darker Attending the Regional Dermatology Training Centre in Northern Tanzania.

Background: Papulosquamous skin diseases can be challenging to diagnose, especially in dark skin. Dermoscopy is reported to be helpful, but few data are available on its use in skin type IV or darker.

Objective: To describe dermoscopic features in plaque-type psoriasis (PP), lichen planus (LP), and pityriasis rosea (PR) patients attending the Regional Dermatology Training Centre in Moshi, Northern Tanzania, and to compare findings with published data.

Methods: A descriptive cross-sectional study was conducted at a tertiary hospital from October 2016 to June 2017. Fifty-six patients with PP, 25 with LP, and 9 with PR were enrolled consecutively. Clinical diagnosis was confirmed with histopathology in 74.4%. Dermoscopic vascular and nonvascular features from 225 lesions were analyzed.

Results: Of the 90 patients enrolled, 58.9% were male and the median age was 50 (interquartile range 32.8-60.0) years. In PP lesions, red dots were found in 64.2% and white scale in 45.5%. In LP lesions the background was violet in 45.5% and 58.2% revealed Wickham striae. In PR lesions a dull red background was found in 50.0%, white scale in 83.3%, but no vessels were detectable.

Conclusion: Dermoscopy features in PP, LP, and PR in dark skin are mostly similar to those in light skin.