Diagnostic Usefulness of Dermoscopy in Differentiating Lichen Planus Pigmentosus from Ashy Dermatosis

Lichen planus pigmentosus is considered a rare variant of lichen planus. It is characterized by acquired dark brown to gray macular pigmentation localized on sun-exposed areas. As lichen planus pigmentosus, ashy dermatosis is also characterized by pigmented lesion and is commonly found in dark-skinned patients. It can be difficult to distinguish lichen planus pigmentosus from ashy dermatosis by the naked eye (1). Dermoscopy can be applied to skin lesions, revealing additional features that can be highly valuable for correct diagnosis. Skin lesions were evaluated via polarized dermoscopy. On dermoscopy, a brownish background with brownish – blackish globules and dots with a linear distribution were found in lichen planus pigmentosus. A bluish background with small bluish dots and globules and white areas were seen in ashy dermatosis. Dermoscopy could provide valuable information for the diagnosis of LPP and aids in differentiating it from ashy dermatosis.