Hair Growth Disorders Research Articles

576 The role of hepatocyte growth factor in human hair follicle – dermal white adipose tissue communication

Although human dermal white adipose tissue (DWAT) envelopes scalp hair follicles (HFs), their underlying bidirectional communication remains unexplored. Recently, we determined that culturing human HFs with surrounding DWAT promoted hair growth and pigmentation ex vivo. The current study aimed to further expand knowledge of the human DWAT-HF axis. Intriguingly, proteomic analysis identified hepatocyte growth factor (HGF) as the most abundantly-secreted DWAT product within long-term HF+DWAT ex vivo cultures. Therefore, we chose to stimulate HFs with HGF ex vivo. Both HFs cultured with DWAT, or HGF in the absence of DWAT showed a significantly increased pigment content, number of gp100+ melanocyte cells and melanocyte dendrites. These positive effects were partially ablated by a neutralizing HGF antibody added to HF+DWAT. As expected, HGF-treated HFs displayed increased proliferation and decreased apoptosis within matrix keratinocytes, effects mirrored by culturing HFs with surrounding DWAT. Transcriptomic analysis of HFs treated with HGF (6hr) revealed that HGF up-regulated PAX3 and SOX10, as well as VEGFA and WNT5B. Gene expression analysis on 24hr cultures coupled with IPA revealed that key Wnt pathway inhibitors are down-regulated in HFs treated with HGF, whereas Wnt agonists, WNT6 and WNT10B, show an upward trend for HF+HGF and HF+DWAT. Here we provide the first evidence that human DWAT communicates with adjacent scalp HFs by secreting HGF, one of the most potent promoters of hair growth and pigmentation. This study designates human perifollicular adipocytes and HGF-dependent DWAT-HF communication an intriguing novel target for therapeutic intervention in the future management of disorders of hair growth or pigmentation.

Cholesterol homeostasis: Links to hair follicle biology and hair disorders.

Lipids and lipid metabolism are critical factors in hair follicle (HF) biology, and cholesterol has long been suspected of influencing hair growth. Altered cholesterol homeostasis is involved in the pathogenesis of primary cicatricial alopecia, mutations in a cholesterol transporter are associated with congenital hypertrichosis, and dyslipidaemia has been linked to androgenic alopecia. The underlying molecular mechanisms by which cholesterol influences pathways involved in proliferation and differentiation within HF cell populations remain largely unknown. As such, expanding our knowledge of the role for cholesterol in regulating these processes is likely to provide new leads in the development of treatments for disorders of hair growth and cycling. This review describes the current state of knowledge with respect to cholesterol homeostasis in the HF along with known and putative links to hair pathologies.

Can plant-derived phytochemicals provide symptom relief for hair loss? A critical review.

It is known that hair growth disorders and hair loss can cause personal distress and affect well-being. Whilst clinical conditions remain a target for medical research, current research on hair follicle biology and hair growth control mechanisms also provides opportunities for a range of non-medical and cosmetic interventions that have a modulating effect on the scalp and follicle function. Furthermore, an improvement of the hair fibre characteristics (cuticle structure, cortex size and integrity) could add to the overall positive visual effect of the hair array. Since phytochemicals are a popular choice because of their traditional appeal, this review provides a critical evaluation of the available evidence of their activity for hair benefit, excluding data obtained from animal tests, and offers recommendations on improving study validity and the robustness of data collection in pre-clinical and clinical studies.

Solid Lipid Nanoparticles Containing <i>Pueraria mirifica</i> Ethanolic Extract for Hair Growth Promotion

Pueraria mirifica (PM) extract is locally used to promote hair growth. However, the effective transdermal delivery system should be prepared to deliver the extract through the skin barrier. The objective of this study was to develop solid lipid nanoparticles (SLN) containing PM ethanolic extract for hair growth promotion. The cell viability and proliferation of human follicle dermal papilla cells (HFDPCs) treated with PM extract were evaluated by MTT assay. SLN formulations were developed as a transdermal delivery system of the PM extract, compared with liposomes. The physicochemical properties of these nanoparticles were determined. The in vitro skin permeation study was also evaluated by Franz type diffusion cells. For the result, PM extract was a good safety herbal extract, which no cytotoxicity at the concentrations from 1 to 1,000 μg/ml. The cell proliferation of PM extract treated HFDPCs significantly increased in a dose-dependent manner, indicating the possibility to promote hair growth at the concentrations from 10 to 100 μg/ml. For formulation development, 5% (w/v) PM extract-loaded SLN exhibited small particle size (93.83 ± 0.32 nm) with narrow size distribution and negatively charged. This formulation had the highest percent entrapment efficiency (42.64 ± 0.47%), followed by SLN containing 1% (w/v) PM extract (8.84 ± 0.24%) and undetectable in liposomes. For the skin permeation result, SLN containing 5% (w/v) of PM extract could penetrate through the skin more than solution form. Therefore, the small particle size and high PM extract entrapped in SLN exhibited higher PM extract penetrated through the skin barrier and hair follicles than PM ethanolic extract solution. PM extract-loaded SLN might be an effective formulation for hair growth disorders treatment.

Hair Growth Promoting Effect of 4HGF Encapsulated with PGA Nanoparticles (PGA-4HGF) by β-Catenin Activation and Its Related Cell Cycle Molecules.

Poly-γ-glutamic acid (γ-PGA)-based nanoparticles draw remarkable attention as drug delivery agents due to their controlled release characteristics, low toxicity, and biocompatibility. 4HGF is an herbal mixture of Phellinus linteus grown on germinated brown rice, Cordyceps militaris grown on germinated soybeans, Polygonum multiflorum, Ficus carica, and Cocos nucifera oil. Here, we encapsulated 4HGF within PGA-based hydrogel nanoparticles, prepared by simple ionic gelation with chitosan, to facilitate its penetration into hair follicles (HFs). In this study, we report the hair promoting activity of 4HGF encapsulated with PGA nanoparticles (PGA-4HGF) and their mechanism, compared to 4HGF alone. The average size of spherical nanoparticles was ~400 nm in diameter. Continuous release of PGA-4HGF was observed in a simulated physiological condition. As expected, PGA-4HGF treatment increased hair length, induced earlier anagen initiation, and elongated the duration of the anagen phase in C57BL/6N mice, compared with free 4HGF treatment. PGA-4HGF significantly increased dermal papilla cell proliferation and induced cell cycle progression. PGA-4HGF also significantly increased the total amount of β-catenin protein expression, a stimulator of the anagen phase, through induction of cyclinD1 and CDK4 protein levels, compared to free 4HGF treatment. Our findings underscore the potential of PGA nanocapsules to efficiently deliver 4HGF into HFs, hence promoting hair-growth. Therefore, PGA-4HGF nanoparticles may be promising therapeutic agents for hair growth disorders.

Biallelic HEPHL1 variants impair ferroxidase activity and cause an abnormal hair phenotype.

Maintenance of the correct redox status of iron is functionally important for critical biological processes. Multicopper ferroxidases play an important role in oxidizing ferrous iron, released from the cells, into ferric iron, which is subsequently distributed by transferrin. Two well-characterized ferroxidases, ceruloplasmin (CP) and hephaestin (HEPH) facilitate this reaction in different tissues. Recently, a novel ferroxidase, Hephaestin like 1 (HEPHL1), also known as zyklopen, was identified. Here we report a child with compound heterozygous mutations in HEPHL1 (NM_001098672) who presented with abnormal hair (pili torti and trichorrhexis nodosa) and cognitive dysfunction. The maternal missense mutation affected mRNA splicing, leading to skipping of exon 5 and causing an in-frame deletion of 85 amino acids (c.809_1063del; p.Leu271_ala355del). The paternal mutation (c.3176T>C; p.Met1059Thr) changed a highly conserved methionine that is part of a typical type I copper binding site in HEPHL1. We demonstrated that HEPHL1 has ferroxidase activity and that the patient’s two mutations exhibited loss of this ferroxidase activity. Consistent with these findings, the patient’s fibroblasts accumulated intracellular iron and exhibited reduced activity of the copper-dependent enzyme, lysyl oxidase. These results suggest that the patient’s biallelic variants are loss-of-function mutations. Hence, we generated a Hephl1 knockout mouse model that was viable and had curly whiskers, consistent with the hair phenotype in our patient. These results enhance our understanding of the function of HEPHL1 and implicate altered ferroxidase activity in hair growth and hair disorders.

Hair growth control by innate immunocytes: Perifollicular macrophages revisited.

The role of innate immunocytes such as mast cells, γδ T cells, NK cells and macrophages (MACs) in hair growth control under physiological and pathological conditions has recently begun to be re-explored. Here, we revisit the role of resident perifollicular macrophages (pfMACs) located in the hair follicle (HF) mesenchyme (CTS). Substantial, stringently timed fluctuations in the number and localization of pfMACs were first observed long ago during murine HF morphogenesis and cycling. This already suggested some involvement of these innate immunocytes, with a recognized role in tissue remodellingand in hair growth control. The relatively recent demonstration of a Wnt signalling-driven crosstalk between these immunocytes and HF epithelial stem cells in telogen HFs, which promotes anagen induction, has reinvigorated interest in the role that pfMAC plays in hair biology. Besides the apoptosis-associated secretion of stem cell-activating Wnts and the differential secretion of HF-targeting growth factors such as FGF-5 and FGF5s from pfMACs, we also explore how MAC polarization, and thus function, may be influenced by the local metabolic and immune environment. Moreover, we examine how pfMACs may contribute to hair cycle-associated angiogenesis, vascular remodelling, HF immune privilege and immunopathology. On this basis, we discuss why targeting pfMACs may be relevant in the management of hair growth disorders. Finally, we argue that studying pfMACs offers an excellent, clinically relevant model system for characterizing and experimentally manipulating MAC interactions with an easily accessible mammalian, continuously remodelled (mini-)organ under both physiological and pathological conditions.

Randomized controlled trial on a PRP-like cosmetic, biomimetic peptides based, for the treatment of alopecia areata

Background: Alopecia areata (AA) is a non-scarring auto-immune hair disorder. Recent researches explained the role of growth factors (GFs) in hair follicle cycling. The main reservoir of GFs are alpha-granules of platelets and novel procedures have been implemented aimed at collecting platelet-rich plasma (PRP). PRP has been safely implemented in many medical applications and has also been successfully used as alternative cell-based therapy for the treatment of hair growth disorders, among which also AA.Objectives: By means of a randomized double-blinded, placebo and active-controlled, parallel group study we have studied the efficacy of a cosmetic product (named TR-M-PRP plus) comprising biomimetic peptides specific for hair growth, mimicking PRP composition for the treatment of AA. Subjects were treated for three months and evaluated, at the end of the study and after one month of follow-up, as regards hair growth using SALT score.Results: TR-M-PRP plus-like topic produced a statistically significant (p < .001) clinical improvement in SALT score after 3 months of therapy, compared to baseline. Hair growth results further improved after 1 month of follow-up.Conclusions: This clinical investigation suggests that the biotechnological designed PRP-like cosmetic could represent a valid and safer alternative to autologous PRP for the treatment of AA.

Identifying novel strategies for treating human hair loss disorders: Cyclosporine A suppresses the Wnt inhibitor, SFRP1, in the dermal papilla of human scalp hair follicles.

Hair growth disorders often carry a major psychological burden. Therefore, more effective human hair growth–modulatory agents urgently need to be developed. Here, we used the hypertrichosis-inducing immunosuppressant, Cyclosporine A (CsA), as a lead compound to identify new hair growth–promoting molecular targets. Through microarray analysis we identified the Wnt inhibitor, secreted frizzled related protein 1 (SFRP1), as being down-regulated in the dermal papilla (DP) of CsA-treated human scalp hair follicles (HFs) ex vivo. Therefore, we further investigated the function of SFRP1 using a pharmacological approach and found that SFRP1 regulates intrafollicular canonical Wnt/β-catenin activity through inhibition of Wnt ligands in the human hair bulb. Conversely, inhibiting SFRP1 activity through the SFRP1 antagonist, WAY-316606, enhanced hair shaft production, hair shaft keratin expression, and inhibited spontaneous HF regression (catagen) ex vivo. Collectively, these data (a) identify Wnt signalling as a novel, non–immune-inhibitory CsA target; (b) introduce SFRP1 as a physiologically important regulator of canonical β-catenin activity in a human (mini-)organ; and (c) demonstrate WAY-316606 to be a promising new promoter of human hair growth. Since inhibiting SFRP1 only facilitates Wnt signalling through ligands that are already present, this ‘ligand-limited’ therapeutic strategy for promoting human hair growth may circumvent potential oncological risks associated with chronic Wnt over-activation.

Msi2 Maintains Quiescent State of Hair Follicle Stem Cells by Directly Repressing the Hh Signaling Pathway

Hair follicles (HFs) undergo precisely regulated cycles of active regeneration (anagen), involution (catagen), and relative quiescence (telogen). Hair follicle stem cells (HFSCs) play important roles in regenerative cycling. Elucidating mechanisms that govern HFSC behavior can help uncover the underlying principles of hair development, hair growth disorders, and skin cancers. RNA-binding proteins of the Musashi (Msi) have been implicated in the biology of different stem cell types, yet they have not been studied in HFSCs. Here we utilized gain- and loss-of-function mouse models to demonstrate that forced MSI2 expression retards anagen entry and consequently delays hair growth, whereas loss of Msi2 enhances hair regrowth. Furthermore, our findings show that Msi2 maintains quiescent state of HFSCs in the process of the telogen-to-anagen transition. At the molecular level, our unbiased transcriptome profiling shows that Msi2 represses Hedgehog signaling activity and that Shh is its direct target in the hair follicle. Taken together, our findings reveal the importance of Msi2 in suppressing hair regeneration and maintaining HFSC quiescence. The previously unreported Msi2-Shh-Gli1 pathway adds to the growing understanding of the complex network governing cyclic hair growth.

Inhibitory Effects of Polyacetylene Compounds from Panax ginseng on Neurotrophin Receptor-Mediated Hair Growth.

Neurotrophins play an important role in the control of the hair growth cycle. Therefore, neurotrophin receptor antagonists have therapeutic potential for the treatment of hair growth disorders. In this study, we investigated the inhibitory effect of Panax ginseng, a medicinal plant commonly used to treat alopecia, on the binding of neurotrophins to their receptors. In addition, we isolated and characterized the bioactive compounds of P. ginseng extracts. P. ginseng hexane extracts strongly inhibited brain-derived neurotrophic factor (BDNF)-TrkB and β-nerve growth factor (β-NGF)-p75 neurotrophin receptor (p75NTR) binding. Furthermore, we identified the following 6 polyacetylene compounds as the bioactive components in P. ginseng hexane extract: panaxynol (1), panaxydol (2), panaxydol chlorohydrin (3), 1,8-heptadecadiene-4,6-diyne-3,10-diol (4), panaxytriol (5), and dihydropanaxacol (6). In particular, compounds 4, 5, and 6 significantly inhibited BDNF-TrkB binding in a dose-dependent manner. To identify the structural component mediating the inhibitory effect, we investigated the effects of the hydroxyl moiety in these compounds. We found that the inhibitory effect of panaxytriol (5) was strong, whereas the inhibitory effect of Ac-panaxytriol (7) was relatively weak. Our findings suggest that P. ginseng-derived polyacetylenes with a hydroxyl moiety might provide therapeutic benefits to patients with hair growth disorders such as alopecia by inhibiting the binding of neurotrophins to their receptors. Although saponins have been proposed to be the primary mediators of the effects of P. ginseng on hair growth, this study revealed that polyacetylene compounds exert similar effects.

217 The adenosine-generating ecto-enzyme CD73 regulates human hair growth

217 The adenosine-generating ecto-enzyme CD73 regulates human hair growth

The role of hyperinsulinemia as a cardiometabolic risk factor independent of obesity in polycystic ovary syndrome

The aim of this study was to utilize various insulin resistance measuring methods to determine whether insulin resistance and other parameters impact the serum lipid levels of polycystic ovary syndrome (PCOS) patients and how the serum lipid levels in these patients are affected by the body mass index (BMI). Our dataset included patients between the ages of 16 and 42 (N = 228) from the outpatient endocrinology clinic of the Department of Obstetrics and Gynecology, who demonstrated increased hair growth and bleeding disorders and came for a routine oral glucose tolerance test (OGTT). Differences in the serum lipid levels were evaluated by t-test and linear regression analysis after adjusting for BMI. A stepwise regression model was constructed to evaluate the influence of each variable on the lipid levels. In PCOS patients, we found that dyslipidemia is more prevalent among hyperinsulinemic women compared with normoinsulinemic women, even after normalizing for BMI. PCOS patients with insulin resistance, determined by the insulin sensitivity index (ISI) method, showed more significant lipid abnormalities such as low high-density lipoprotein (HDL) and apo-A levels and high total cholesterol, low-density lipoprotein (LDL) and apo-B levels than if insulin resistance (IR) determination was based on insulin level or homeostatic model assessment (HOMA).

The Diagnosis and Treatment of Hair and Scalp Diseases.

Hair loss is caused by a variety of hair growth disorders, each with its own pathogenetic mechanism. This review is based on pertinent articles retrieved by a selective search in PubMed, on the current German and European guidelines, and on the authors' clinical and scientific experience. Excessive daily hair loss (effluvium) may be physiological, as in the postpartum state, or pathological, due for example to thyroid disturbances, drug effects, iron deficiency, or syphilis. Androgenetic alopecia generally manifests itself in women as diffuse thinning of the hair over the top of the scalp, and in men as receding temporal hairlines and loss of hair in the region of the whorl on the back of the head. Alopecia areata is patchy hair loss arising over a short time and involving the scalp, eyebrows, beard, or entire body. The hair loss of alopecia areata is reversible in principle but hard to treat. Folliculitis decalvans is a form of alopecia with scarring, characterized by inflamed papules, pustules, and crusts at the edges of the lesions. Lichen planopilaris generally presents with small patches of baldness, peripilar erythema, and round areas of skin scaling. Kossard's frontal fibrosing alopecia is characterized by a receding hairline and loss of eyebrows. Hair loss is a symptom, not a diagnosis. The pathogenesis of the alopecias involves a range of genetic, endocrine, immune, and inflammatory processes, each of which calls for its own form of treatment.

A Guide to Studying Human Hair Follicle Cycling In Vivo

Hair follicles (HFs) undergo life-long cyclical transformations, progressing through stages of rapid growth (anagen), regression (catagen), and relative “quiescence” (telogen). Since HF cycling abnormalities underlie many human hair growth disorders, the accurate classification of individual cycle stages within skin biopsies is clinically important and essential for hair research. For preclinical human hair research purposes, human scalp skin can be xenografted onto immunocompromised mice to study human HF cycling and manipulate long-lasting anagen in vivo. While available for mice, a comprehensive guide on how to recognize different human hair cycle stages in vivo is lacking. Here, we present such a guide, which uses objective, well-defined, and reproducible criteria and integrates simple morphological indicators with advanced, (immuno)-histochemical markers. This guide also characterizes human HF cycling in xenografts and highlights the utility of this model for in vivo hair research. Detailed schematic drawings and representative micrographs provide examples of how best to identify human HF stages, even in sub-optimally sectioned tissue, and practical recommendations are given for designing human-on-mouse hair cycle experiments. Thus, this guide seeks to offer a benchmark for human hair cycle stage classification, for both hair research experts and newcomers to the field.

Dynamic Changes of the Quantitative Distribution,Apoptosis and Proliferation of T and B Cells in the Skin of KM Mutant Mice

To observe the change of quantitative distribution,apoptosis and proliferation of T and B cells in the skin of KM mutant mice. We chose 1-,3-,6-,9-,22-day,3-,6-month-old KM mutant and wild-type mice to detect the changes of T and B lymphocytes using blood routine tests and immunohistochemical staining. Apoptosis was detected by TUNEL staining and proliferation by proliferating cell nuclear antigen (PCNA) staining. T cells on KM mutant mice skin were mainly seen in epidermis and dermis. They increased on the first day to 6(th) day after birth and decreased on the 9(th) and 22(nd) day,but after 3-month-old,their number began to increase;at the time of 6 months,the number of B cells also increased. The apoptosis of the skin hair follicle and sebaceous gland cells were more obvious in KM mutant mice than in wild-type mice,with the maximal apoptosis occurred at the age of 22-day-old in both groups. The proliferation of epidermal basal cells in KM mutant mice between 1 to 9-day-old was not significantly different from that in the wild-type mice,but decreasing on the 22(nd) day and 3(rd) month and increasing in the 6(th) month. The proliferation in hair follicle and sebaceous glands decreased on 9(th) day,increased on 22(nd) day,and deceased on the 3(rd) month again. The quantitative distribution,apoptosis,and proliferation of T and B lymphocytes abnormally change in the skin tissue of KM spontaneous mutant mice. They may lead to immune and hair growth disorders and promote the inflammatory responses.

Pseudofolliculitis cutis: a vexing disorder of hair growth.

Pseudofolliculitis cutis (PFC) is a troublesome and potentially disfiguring cutaneous disorder characterized by a chronic inflammatory response to ingrown hair. Despite a simple precipitating stimulus, ingrown hair, PFC has a relatively complex aetiology that can involve grooming practices, hair type, genetic predisposition and medication history. Curly hair and a single-nucleotide substitution in the gene encoding keratin 75 may act synergistically to increase the risk for developing this condition. PFC is most common in men of sub-Saharan African lineage, but can occur in men and women of many different ethnicities, particularly in body areas where hair is coarse, abundant and subject to traumatic removal. Treatment options for PFC can be divided into three main categories: modifying hair removal practices, managing symptoms with medication, and long-term hair removal with laser therapy. Laser hair removal is safe and effective in most skin types and has become increasingly popular among dermatologists in the treatment of PFC. However, it is imperative that the laser system and parameters are specifically matched to the patient's skin type.

Resting no more: re-defining telogen, the maintenance stage of the hair growth cycle.

The hair follicle (HF) represents a prototypic ectodermal-mesodermal interaction system in which central questions of modern biology can be studied. A unique feature of these stem-cell-rich mini-organs is that they undergo life-long, cyclic transformations between stages of active regeneration (anagen), apoptotic involution (catagen), and relative proliferative quiescence (telogen). Due to the low proliferation rate and small size of the HF during telogen, this stage was conventionally thought of as a stage of dormancy. However, multiple lines of newly emerging evidence show that HFs during telogen are anything but dormant. Here, we emphasize that telogen is a highly energy-efficient default state of the mammalian coat, whose function centres around maintenance of the hair fibre and prompt responses to its loss. While actively retaining hair fibres with minimal energy expenditure, telogen HFs can launch a new regeneration cycle in response to a variety of stimuli originating in their autonomous micro-environment (including its stem cell niche) as well as in their external tissue macro-environment. Regenerative responses of telogen HFs change as a function of time and can be divided into two sub-stages: early 'refractory' and late 'competent' telogen. These changing activities are reflected in hundreds of dynamically regulated genes in telogen skin, possibly aimed at establishing a fast response-signalling environment to trauma and other disturbances of skin homeostasis. Furthermore, telogen is an interpreter of circadian output in the timing of anagen initiation and the key stage during which the subsequent organ regeneration (anagen) is actively prepared by suppressing molecular brakes on hair growth while activating pro-regenerative signals. Thus, telogen may serve as an excellent model system for dissecting signalling and cellular interactions that precede the active 'regenerative mode' of tissue remodeling. This revised understanding of telogen biology also points to intriguing new therapeutic avenues in the management of common human hair growth disorders.

HIF‐2α/ARNT complex regulates hair development via induction of p21 Waf1/Cip1 and p27 Kip1

The hypoxia-inducible factors HIF-1α or HIF-2α form heterodimeric complexes with the aryl hydrocarbon receptor nuclear translocator (ARNT). HIF-1α/ARNT and HIF-2α/ARNT complexes activate hypoxia-inducible genes that play critical roles in angiogenesis, anaerobic metabolism, and other processes in response to O2 deprivation. HIF-2α is known to regulate the function and/or differentiation of stem cells by activating the POU domain transcription factor Oct4; however, the precise underlying mechanism is unknown. This study examined the role of HIF-2α/ARNT in hair development using conditional-knockout mice, in which Arnt was specifically deleted in keratinocytes. In wild-type mice, HIF-2α and ARNT were highly expressed in the precortex above the hair matrix, an area containing differentiating stem cells. An analysis of hair size and type in these mice showed that loss of ARNT decreased the production of zigzag hairs, corresponding to reduced expression of HIF-2α and induction of the mammalian cyclin-dependent kinase inhibitors p21(Waf1/Cip1) and p27 (Kip1). The results suggest that the HIF-2α/ARNT complex regulates hair follicle differentiation via induction of p21(Waf1/Cip1) and possibly p27(Kip1), as p27(Kip1) expression was not altered in ARNT knockout mice. The findings provide insight into a possible mechanism underlying hair growth disorders and can be useful for future studies on hair follicle response to insults, such as chemotherapy and ionizing radiation.

Red face revisited: Disorders of hair growth and the pilosebaceous unit

This paper reviews the recent literature on the diseases of the hair and pilosebaceous unit that may cause a red face. We discuss the epidemiology, clinicals, pathogenesis, and therapy of lichen planopilaris with its variants, discoid lupus erythematosus, folliculitis decalvans, dissecting folliculitis, acne keloidalis nuchae, pseudofolliculitis barbae, tinea capitis, tinea barbae, folliculitis of diverse causative factors and inflammatory follicular keratotic syndromes, ulerythema ophryogenes, atrophoderma vermiculatum, keratosis follicularis spinulosa decalvans, and folliculitis spinulosa decalvans.