Carpet tacking is characteristically seen in

Discoid lupus erythematosus (DLE, also called chronic cutaneous LE) is characterized by discrete lesions, most often found on the face, scalp, and/or external ears. The lesions are erythematous papules or plaques with a thick, adherent scale that occludes hair follicles (follicular plugging). When the adherent scale is removed from the lesions of discoid lupus erythematosus, the undersurface of the scale shows horny plugs that have occupied patulous hair follicles. (Carpet tack sign) Ref Harrison 20th edition pg 1244