The spectrum of fibrosing alopecias

Abstract

Lichen planopilaris (LPP) is a primary lymphocytic cicatricial alopecia considered the most common cause of scarring hair loss in adults. It has been classified into three clinical variants: classical LPP, frontal fibrosing alopecia (FFA) and Graham Little-Piccardi-Lassueur syndrome. Classical LPP usually presents as a circumscribed cicatricial patch on the vertex and FFA as a band-like scarring alopecia of the frontotemporal hairline. Fibrosing alopecia in a pattern distribution (FAPD) and lichen planopilaris diffuse pattern (LPPDP) are two recently described subtypes of LPP that exhibit a diffuse involvement of the androgen-dependent region or the whole scalp, respectively. Classical LPP, FFA, FAPD and LPPDP share trichoscopic (cicatricial areas, absence of follicular openings, perifollicular erythema and hyperkeratosis) and histologic features (interface dermatitis involving follicular epithelium and concentric fibrosing around the isthmus and infundibulum).The remarkable clinical and histological overlap between these entities has led to the concept that these diseases exist along a spectrum. In the effort to identify classical LPP, FFA, FAPD and LPPDP with an umbrella term, we suggest to use 'lichenoid alopecias', as the distinguishing hallmark of these diseases is the lichenoid bandlike inflammatory infiltrate in the superficial dermis involving the infundibulum and isthmus of the hair follicle.

Trichoscopy – a valuable tool for identifying conditions mimicking androgenetic alopecia

“…Patients usually complain of a long-lasting history of hair loss variably associated with scalp dysesthesia. 32 Trichoscopy of FAPD shares similar features characteristic of AGA: hair diameter diversity, peripilar sign, and yellow dots, but the predominance of single hair follicles, perifollicular erythema, perifollicular scaling, and perifollicular white halo indicate cicatricial alopecia. 33 Partial or total loss of the follicular openings may also be seen.…”

“…FAPD is a diffuse, non‐patchy cicatricial alopecia limited to the area of androgenetic hair loss 24 (Figure 2). Patients usually complain of a long‐lasting history of hair loss variably associated with scalp dysesthesia 32 …”