Which of the following is a recognized variant of lichen planus characterized by follicular involvement, leading to scarring alopecia, particularly on the scalp?

Explanation

Lichen planopilaris is a distinct variant of lichen planus that specifically targets hair follicles. It presents with perifollicular erythema, scaling, and ultimately results in permanent, scarring alopecia, most commonly affecting the scalp. Lichen planus pigmentosus is characterized by slate-grey or brownish macules and patches, often in sun-exposed areas. Hypertrophic lichen planus presents as thick, verrucous, intensely pruritic plaques, typically on the shins. Annular lichen planus forms ring-shaped lesions with an active border and central clearing.