Rare and misdiagnosed entity fibrosing alopecia in a pattern distribution: A case report

Fibrosing alopecia in a pattern distribution (FAPD) is a lymphocytic primary cicatricial alopecia characterized by the combination of clinical and histopathological features of lichen planopilaris (LPP) and androgenetic alopecia (AGA). It remains unclear whether FADP corresponds to an AGA with a lichenoid tissue reaction pattern or to a patterned LPP. A 34-year-old female patient presented with a 4-year history of progressive hair loss involving the central area of the scalp. She reported a centrifugal expansion in the midscalp, with mild pruritus. A previous diagnosis of AGA was made by her primary-care dermatologist. She had been treated with minoxidil 5% solution for 3 months without any clinical improvement. Furthermore, anamnesis revealed no history of chemical hair straighteners or hair styling that involved important traction. Neither symptoms of hyperandrogenism nor hair losses' patterns in the family history were reported. Scalp examination revealed severe symmetric hair loss in a centroparietal distribution, decrease in follicular density, mild perifollicular erythema, and scaling within the alopecic area (Figure 1A). The trichoscopic examination demonstrated perifollicular hyperkeratosis, large white irregular dots lacking follicular openings and milky red areas. Hair shaft abnormalities were also identified, including hair diameter heterogeneity, predominance of single-hair follicles and hair shaft dystrophy (Figure 1B). A trichoscopy-guided biopsy revealed a superficial fibrosing dermatitis, miniaturized hair follicles with concentric lamellar fibrosis, and free hair shaft material surrounded by foreign-body giant cells and (Figure 2). There were no interface dermatitis and no suppuration. All clinical, trichoscopic, and histological features observed in our patient were consistent with the diagnosis of FAPD. The patient was treated with intralesional injections of triamcinolone acetonide 20 mg/mL every month and twice daily applications of minoxidil 2% during the follow-up period. Fibrosing alopecia in a pattern distribution is a distinctive pattern of scarring alopecia originally described by Zinkernagel and Trueb in 19 patients (15 women and 4 men) presenting a patterned hair loss similar to AGA but with histopathologic signs of both LPP and AGA.1 Approximately 188 cases (164 women, 24 men) have been reported in the literature with ages ranging from 21 to 82 years.2 Griggs et al. proposed a set of diagnostic criteria for the diagnosis of FADP, including patterned hair loss involving the androgen-dependent scalp with dermoscopic and/or histopathologic evidence of follicular inflammation and fibrosis. The exclusion criteria correspond to patchy or asymmetric hair loss.2 Our patient meets the current diagnostic criteria except for lichenoid infiltrate and interface dermatitis, which may require the identification of an acutely affected vellus hair. These criteria provide an extremely useful tool for diagnostic consistency by distinguishing FADP from other cicatricial alopecias.2 The differential diagnosis of FADP includes AGA and members of fibrosing alopecias. Alopecia of FADP and AGA is similarly insidious and predominantly affects the androgen-dependent scalp (Hamilton-Norwood, Ludwig, and Christmas tree distributions).2 Whereas in active FADP, scalp symptoms such as pain and pruritus are reported, dysesthesia of the scalp is less obvious in AGA.3 Hair shaft diameter variability and an increased proportion of single hair follicles are common trichoscopic features of FADP and AGA.2 However, perifollicular erythema and perifollicular hyperkeratosis are only present in FADP.2 On the other hand, yellow dots are observed in AGA and correspond to empty follicular ostia filled with keratotic material and/or sebum.4 It is important to note that a reduction in the follicular density can be seen in the late stages of AGA.5 The term fibrosing alopecia proposed by Du et al. refers to a group of primary lymphocytic cicatricial alopecias which are mainly distinguished by the clinical pattern of hair loss, of which LPP is the prototype. This group includes LPP, frontal fibrosing alopecia (FFA), FAPD, cicatricial pattern hair loss (CPHL), and LPP with a diffuse pattern.6 Each of these entities may demonstrate lichenoid folliculitis and concentric fibrosis around the isthmus and infundibulum.3, 6 LPP presents as asymmetric, patchy hair loss with no preference for androgen-dependent or independent scalp. FFA is commonly characterized by a progressive symmetric hairline recession in the frontotemporal and/or frontoparietal region. Clinically, FAPD and FFA with crown involvement can be confused, although the presence of anisotrichia and vellus hair can tell FAPD from FFA with crown involvement. FFA frequently affects body hair, eyelashes, and eyebrows as well. Despite the fact that FFA and AGA can coexist, only the marginal scalp gets scarred.6 Cicatricial pattern hair loss involves androgen-dependent areas with the presence of focal atrichia, described as "pencil–eraser-sized" areas of patchy scarring, but lacking erythema and perifollicular hyperkeratosis observed in FADP.3, 6 In FAPD and CPHL the lymphocytic infiltrate involves predominantly the miniaturized hair follicles, while in LPP the lymphocytic infiltrate involves mainly the terminal follicles.3 In patients with dark pigmentation, central centrifugal cicatricial alopecia (CCCA), and FAPD may coexist. The clinical appearance of the 2 illnesses differs, with FAPD presenting with patterned hair thinning that is quite similar to AGA, while CCCA manifests as a centrifugally growing patch of alopecia. FAPD can be distinguished from CCCA by the presence of a lichenoid infiltrate and an interface dermatitis of the follicular epithelium. However, early stages of both diseases can clinically and histologically overlap.2 FAPD's pathophysiology is not well known. The higher hair follicle is thought to be the target of the inflammatory response in this type of lymphocytic primary cicatricial alopecia, which eventually leads to fibrosis follicular tracts. It is thought to be a T-cell-mediated autoimmune reaction associated with apoptosis of follicular epithelial cells. The observation of graft-versus-host illness manifesting as FAPD has been postulated to constitute a model for studying the underlying disease mechanisms. In the other hand, many cases of FAPD involve patients with a family history of AGA. Nevertheless, genetic investigations are not yet accessible. Instances of familial FAPD with a simultaneous presentation in brothers provide early evidence of a genetic foundation to the condition beyond that of AGA alone.2, 7, 8 Foreign-body granulomas to released hair shaft material, as seen in our patient, have been reported in several forms of hair loss, including alopecia areata, folliculitis decalvans, central centrifugal cicatricial alopecia, LPP, and FADP.7 Their superficial location devoid of suppuration is suggestive of an advanced stage of LPP.7 Treatment options for FAPD are limited and were only reported in a few retrospective series and case reports. Intralesional corticosteroid therapy combined with topical minoxidil aims to decrease inflammation and thicken miniaturized hairs.2 Oral antiandrogen therapies may be beneficial at the very early stages of the disease, prior to the onset of the fibrosis process. Further studies are needed to evaluate their potential effectiveness. Fibrosing alopecia in a pattern distribution represents a novel entity, which can be easily misdiagnosed as AGA. Dermoscopy, a non-invasive technique, can provide important clues for early diagnosis, and may help in selecting the optimum site for biopsy. M.T., N.F., and R.F. wrote the manuscript with support from S.M. and B.S. analyzed the histopathological images. C.B. and M.D. supervised the project. All authors have read and approved the final manuscript. The authors declare that there are no conflicts of interest in this work. The examination of the patient was conducted according to the principles of the Declaration of Helsinki. The authors certify that they have obtained all appropriate patient consent forms, in which the patient gave his consent for images and other clinical information to be included in the journal. The patient understands that his name and initial will not be published and due effort will be made to conceal his identity, but that anonymity cannot be guaranteed. The patient gave us written informed consent to perform all necessary investigations, to take clinical photographs, and use them for research purposes and publication.