Lichen Planus Pigmentosus Linked to Alopecias, Lichenoid Infiltrate Around Facial Hair Follicles

Lichen planus pigmentosus may be associated with frontal fibrosing alopecia (FFA) and fibrosing alopecia in a pattern distribution (FAPD) in women with Fitzpatrick skin phototype III to VI and may involve the facial hair follicle, researchers reported in a letter published in the Journal of the European Academy of Dermatology and Venereology. 

The cross-sectional study included 16 women (aged 41 to 80 years) with biopsy-confirmed cicatricial alopecia and dermatoscopic features of lichen planus pigmentosus. All participants underwent facial biopsy at the zygomatic area. Dermoscopy was performed, and histology was conducted with use of multiple horizontal sections of each specimen.

Within the cohort, 4 patients (25%) had phototype IV, 5 (31%) had phototype V, 7 (44%) had phototype VI, 8 (50%) had FFA, and 8 (50%) had FAPD. A total of 12 patients (75%) had facial papules on the forehead and temporal areas.

The most common dermatoscopic finding of facial lichen planus pigmentosus was brown to grey-blue asymmetric perifollicular hyperpigmentation, which is strongly associated with the presence of facial papules, according to the researchers. The facial hair follicle was involved in 12 (75%) patients, and 8 (50%) had melanophages around the hair follicle.

“This work shows that lichen planus pigmentosus may be associated with both FFA and FAPD in Fitzpatrick skin phototype III to VI female patients and may involve the facial hair follicle,” stated the investigators.

“Facial hyperpigmentation may present as melanin aggregates from vacuolated hair follicle basal layer cells,” the researchers commented. “It is possible that darker hair pigmentation in patients with higher skin phototypes may predispose a subset to a more frequent incidence of lichen planus pigmentosus.”

The observation of lichenoid infiltrate around facial hair follicles in lichen planus pigmentosus had not been reported previously, according to the study authors.

“Hyperpigmentation in lichen planus pigmentosus may be due to the lichenoid inflammation around the hair follicles, which is mostly seen on higher phototypes,” the researchers stated. They suggest that additional studies are warranted to further explain the current understanding of the role of facial hair follicles in the pathogenesis of primary cicatricial alopecia.

Reference

Dias MFRG, Rezende HD, Furtado Cardoso de Moraes JR, et al. New insights into lichen planus pigmentosus associated with cicatricial alopecia [published online September 4, 2020]. J Eur Acad Dermatol Venereol. doi: 10.1111/jdv.16918