Refractory alopecia areata with single hairs imitating frontal fibrosing alopecia: a prospective observational study

BACKGROUND

Lonely hair sign is considered as a clue to the diagnosis of frontal fibrosing alopecia (FFA).

OBJECTIVE

To report an undescribed variant of alopecia areata (AA) with which the patient developed single hairs and other features similar to FFA and to determine the underlying mechanism.

METHODS

We conducted a prospective observational study in patients who presented with receding hairline and single hairs, evaluating the clinical, trichoscopic, and histological features and their correlation. Immunochemistry studies were performed to describe the microenvironment.

RESULTS

Eighteen patients were enrolled in the study. Despite the similarity to FFA clinically, these patients showed different histopathology which revealed a normal number of pilosebaceous units, one anagen hair in one or more pilosebaceous units, and others in telogen stage, consistent with single hairs under the naked eye or under trichoscopy. The severity of the hair loss assessed by SALT was no more than 50, but the response to conventional therapy was poor.

CONCLUSIONS

This study reports a unique variant of AA. The pathological basis is an increase in the telogen hair follicles, with one anagen hair in one or more pilosebaceous units. Minimal inflammation consisting of CD3+ T lymphocytes and mast cells was demonstrated in the microenvironment.

Divergent progression pathways in male androgenetic alopecia and female pattern hair loss: Trichoscopic perspectives

BACKGROUND

Despite similarities in progressive miniaturization of hair follicles and transition of terminal hairs to vellus hairs, insufficient trichoscopic comparisons between male androgenetic alopecia (MAGA) and female pattern hair loss (FPHL) hinder our ability to select effective treatments.

AIM

Our study aimed to explore gender-specific trichoscopic characteristics of MAGA and FPHL, while formulating hypotheses regarding the progression of these conditions across clinical stages.

METHODS

We classified 126 male MAGA subjects using Hamilton-Norwood Classification and 57 FPHL subjects using adopted Sinclair Scale. Subsequently, we analyzed nine trichoscopic factors divided into three categories: hair-diameter related, hair-number per follicular unit related, and hair density related factors.

RESULTS

Of the nine quantitative trichoscopic factors, hair-diameter and hair-number per follicular unit showed strong correlations with clinical stages in both genders. Hair density, a common trichoscopic factor for hair loss evaluation, weakly correlated with clinical stages in FPHL, but not at all in MAGA. In addition, MAGA was characterized by a progressive reduction in hair-diameter, followed by a reduction in hair-number per follicular unit. FPHL, on the contrary, showed the opposite progression.

CONCLUSIONS

Trichoscopic factors vary with disease severity in a gender-specific manner. Our research highlights that MAGA and FPHL involve two distinct streams: hair-diameter decreasing by hair follicle miniaturization (Stream 1), and hair-number per follicular unit decreasing by hair follicle tri-lineage niche dysfunction (Stream 2). MAGA typically starts from Stream 1 to Stream 2, while FPHL starts from Stream 2. These diverse progression pathways underscore the importance of personalized treatment approaches.

Dermoscopic findings and comparison of usefulness of longitudinal versus transversal sections in the histological diagnosis of alopecia X

BACKGROUND

A combination of dermoscopic and histological findings may provide useful information for the diagnosis of hair follicle diseases. However, there are no studies on dermoscopic-histopathological correlations in dogs affected by alopecia X, and comparison of longitudinal versus transversal sectioning of skin biopsy specimens in the assessment of this hair loss disorder has not been thoroughly investigated.

HYPOTHESIS/OBJECTIVES

The aim of this study was to correlate dermoscopic and histological features using both longitudinal and transversal sectioning of skin biopsy samples to gain additional information for the diagnosis of alopecia X.

ANIMALS

Nineteen Pomeranian dogs affected by alopecia X and five healthy Pomeranians as controls.

MATERIALS AND METHODS

Dermoscopic-histological correlation was performed within the diseased group, whereas histological comparisons against controls. The demographic and clinical characteristics also were related to the histological findings.

RESULTS

The dermoscopic findings revealed scattered, thinned, short hairs mixed with amorphous keratoseborrhoeic-like material (follicular plugging), perifollicular and intrafollicular scaling, and hyperpigmentation varying from pinpoint black spots to a diffuse texture. Dermoscopic findings correlated with histological findings for selected qualitative and quantitative findings. The usefulness of transversal sections was demonstrated in accurately determining the hair follicular density and counts, growth arrest phases and in identifying mineralisation of hair follicle basement membrane when compared to the longitudinal. Conversely, no correlations between histological findings and demographic and clinical characteristics were detected.

CONCLUSIONS AND CLINICAL RELEVANCE

These data provide evidence of the usefulness of dermoscopic evaluation as an accessory diagnostic tool and of transversal sections of skin biopsies as complementary to the diagnosis of alopecia X.

Clinical effects of autologous follicular unit extraction transplantation in the treatment of secondary cicatricial alopecia after infections

OBJECTIVE

To explore the clinical effects of autologous follicular unit extraction (FUE) transplantation in the treatment of secondary scarring alopecia caused by infections, and to evaluate its effectiveness.

METHODS

A retrospective observational study has been conducted, which included nine patients with secondary scarring alopecia caused by infections. All patients underwent initial autologous FUE hair transplantation surgery, and the occurrence of postoperative complications was monitored. Patient satisfaction was evaluated after 12 months post-surgery.

RESULTS

At the follow-up, postoperative satisfaction was 88.9% in nine patients, with only one case of postoperative infection and no incidence of skin necrosis, significant bruising and swelling, unnatural appearance or temporary hair loss.

CONCLUSIONS

Autologous FUE hair transplantation is an effective method for treating secondary scarring alopecia caused by infections. This procedure is minimally invasive, resulting in high patient satisfaction and minimal complications postoperatively.

Epidemiology, clinical characteristics, treatment, and outcomes of proliferating pilar tumors: A systematic review

BACKGROUND

Proliferating pilar tumors (PPTs) are rare cutaneous neoplasms arising from hair follicles that have both malignant and metastatic potential.

OBJECTIVE

To present a systematic review of the epidemiology, clinical characteristics, and treatment and outcome data on PPTs.

METHODS

Using the OVID platform, MEDLINE and Embase were searched from inception until May 26, 2022. All studies that provided original data on PPTs in English were included. References of these studies were also cross-checked to identify any additional relevant articles. Oxford's Levels of Evidence-Based Medicine was used for quality assessment.

RESULTS

A total of 114 articles, providing data on 361 cases of PPTs, were included in our synthesis. Every study included was either a case series or case report. The mean age at diagnosis was 61.7. Most patients in the synthesis were female (71%), and the majority of cases occurred on the scalp (73.1%). The presence or absence of cytological atypia was only reported in one-third of the cases; 36.8% of cases were classified as malignant and 7.5% metastasized. Although no lesions treated with Mohs micrographic surgery required adjuvant radiation and only one reported recurrence occurred after Mohs surgery, there is insufficient data to make conclusions on a superior treatment modality.

LIMITATIONS

All studies in this review were either case reports or case series.

CONCLUSIONS AND RELEVANCE

Our study supports the notion that PPTs occur most commonly on the scalp of elderly female patients. Moreover, our findings confirm that PPT is capable of demonstrating aggressive biology and metastasis. Given the lack of uniformity in histologic description, pathologists should be encouraged to comment on the presence and degree of cytological atypia when reporting cases of rare neoplasms such as the PPT. Greater consensus on diagnosis and classification as well as more robust data is needed regarding optimal management.

MiR-199a-3p Regulates the PTPRF/β-Catenin Axis in Hair Follicle Development: Insights into the Pathogenic Mechanism of Alopecia Areata

Alopecia areata is an autoimmune disease characterized by the immune system attacking self hair follicles, mainly in the scalp. There is no complete cure, and the pathogenesis is still not fully understood. Here, sequencing of skin tissues collected from 1-month-old coarse- and fine-wool lambs identified miR-199a-3p as the only small RNA significantly overexpressed in the fine-wool group, suggesting a role in hair follicle development. MiR-199a-3p expression was concentrated in the dermal papillae cells of sheep hair follicles, along with enhanced β-catenin expression and the inhibition of PTPRF protein expression. We also successfully constructed a mouse model of alopecia areata by intracutaneous injection with an miR-199a-3p antagomir. Injection of the miR-199a-3p agomir resulted in hair growth and earlier anagen entry. Conversely, local injection with the miR-199a-3p antagomir resulted in suppressed hair growth at the injection site, upregulation of immune system-related genes, and downregulation of hair follicle development-related genes. In vivo and in vitro analyses demonstrated that miR-199a-3p regulates hair follicle development through the PTPRF/β-catenin axis. In conclusion, a mouse model of alopecia areata was successfully established by downregulation of a small RNA, suggesting the potential value of miR-199a-3p in the study of alopecia diseases. The regulatory role of miR-199a-3p in the PTPRF/β-catenin axis was confirmed, further demonstrating the link between alopecia areata and the Wnt-signaling pathway.

p63 immunoexpression in hair follicles of normal and alopecia X-affected skin of Pomeranian dogs

BACKGROUND

Alopecia X in Pomeranians is caused by a hair cycle deregulation, associated with downregulation of key regulatory genes of the Wnt and Shh pathways, and stem-cell markers. However, the pathogenesis remains unclear. p63 is an important transcription factor correlated with the aforementioned hair cycle modulating genes.

HYPOTHESIS/OBJECTIVES

The aim of this study was to highlight possible changes of p63 immunohistochemical expression within the hair follicles in canine alopecia X compared with normal skin.

ANIMALS

Skin biopsies from 19 alopecia X-affected and six control Pomeranians were analysed.

MATERIALS AND METHODS

Serial histological sections of skin biopsies harbouring anagen, telogen and kenogen hair follicles were immunohistochemically evaluated for differences in p63 expression in the affected and control samples.

RESULTS

Dogs with alopecia X had a significantly decreased immunoexpression of p63 in telogen and kenogen hair follicles.

CONCLUSIONS AND CLINICAL RELEVANCE

The decrease of p63 immunoexpression observed in canine alopecia X suggests an involvement of p63 in hair cycle.

Effect of overexpression of KLF4 on the growth and development of hair follicles in mice

Hair follicle growth is cyclical, and hair cycle dysfunction can lead to hair follicle-related disorders, including alopecia and hirsutism. The objective was to investigate the influence and underlying mechanism of Krüppel-like factor 4 (KLF4) overexpression on hair follicle growth and development in C57BL/6 mice. To provide a theoretical basis for the biological functions of KLF4 gene in hair follicle development and hair follicle cycle, mice were assigned to three groups: experimental, overexpressing KLF4 (Ad-KLF4); control, expressing green fluorescent protein (Ad-NC); and blank, no treatment. Fur was removed from the dorsal surface, and the mice were intradermally injected with 25 μL 1 × 1010 PFU/mL adenovirus vector (Ad-KLF4 or Ad-NC) at three points. Samples were collected for molecular biological and histological analysis. It was found that mRNA and protein levels of Wnt pathway-associated factors β-catenin, LEF1, hair follicle cell proliferation-related factor Ki67, and hair follicle inner caledrin marker AE15 were all significantly greater in the Ad-NC and blank groups than in Ad-KLF4 mice (P < 0.01). These findings were confirmed by immunohistochemical analysis. Hair growth was monitored photographically for 14 days, showing an absence of growth in the injected region of the KLF4-overexpressing mice in contrast to non-overexpressing areas where hair growth was normal. HE staining showed that hair follicles in the blank and Ad-NC mice were normal, while those in the KLF4-overexpressing areas remained in telogen or early anagen with spherical dermal papillae situated at the edge of the dermis and subcutaneous tissue without an inner heel sheath. In conclusion, it was found that KLF4 downregulated key Wnt/β-catenin-associated factors during follicular regeneration in mice, reducing both follicular development and growth.

Folliculotropic Mycosis Fungoides In A Child: A Rare Case

Folliculotropic mycosis fungoides (FMF) is a variant of mycosis fungoides characterized by infiltration of hair follicle epithelium by neoplastic lymphoid cells. Generally, it is usually typified by indurated plaques and tumours mainly on the head and neck. However, a wide range of clinical signs have been noted. The clinical presentation of FMF may include prurigo-like lesions, acneiform lesions, cysts, nodules, areas of scarring alopecia, and hypopigmented plaques or papules with follicular prominences. The average age of diagnosis is 60 years while it is rare in childhood and adolescence. We discuss the case of a 12-year-old male patient who had an asymptomatic, erythematous, infiltrating plaque across his left nasolabial fold for three months prior to presentation. Histological assessment of lesion showed characteristic findings of follicular mucinosis with predominance of CD4+ lymphocytes and immunohistochemical studies were positive for CD3+ stains. An increased CD4:CD8 ratio and negative CD20 was also shown. Both findings were consistent with diagnosis of FMF.

Follicular dysplasia and hair loss in white-tailed deer (Odocoileus virginianus)

There have been unpublished reports of a follicular dysplastic syndrome in adult white-tailed deer (Odocoileus virginianus; WTD), known colloquially as "toothpaste hair disease." The current report aims to describe the gross and histologic lesions in skin samples from 2 adult WTDs that presented to the Wisconsin Department of Natural Resources and the Wisconsin Veterinary Diagnostic Laboratory with reports of hair loss in 2018. Both cases were grossly alopecic with sparing of the distal extremities and variably the head and neck. Histologic features included hair follicles and adnexa present in relatively normal numbers, dilated and misshapen follicles, and dysplastic hair bulbs. Hair follicles were empty, contained fragmented and irregular hair shafts, or contained concretions of keratin. Hair bulbs were rarely infiltrated by small lymphocytes, suggestive of alopecia areata as a cause of the gross appearance. This condition does not appear to be directly responsible for WTD mortality but presumably would predispose affected animals to greater environmental exposure. Evaluation of additional affected individuals is warranted to further evaluate for features of alopecia areata.

Alopecia Areata: Current Treatments and New Directions

Alopecia areata is an autoimmune hair loss disease that is non-scarring and is characterized by chronic inflammation at the hair follicle level. Clinically, patients' presentation varies from patchy, circumscribed scalp involvement to total body and scalp hair loss. Current management is guided by the degree of scalp and body involvement, with topical and intralesional steroid injections as primarily first-line for mild cases and broad immunosuppressants as the mainstay for more severe cases. Until recently, the limited number of blinded, randomized, placebo-controlled clinical trials for this disease had made establishing an evidence-based treatment paradigm challenging. However, growing insights into the pathogenesis of alopecia areata through blood and tissue analysis of human lesions have identified several promising targets for therapy. T-helper (Th) 1/interferon skewing has traditionally been described as the driver of disease; however, recent investigations suggest activation of additional immune mediators, including the Th2 pathway, interleukin (IL)-9, IL-23, and IL-32, as contributors to alopecia areata pathogenesis. The landscape of alopecia areata treatment has the potential to be transformed, as several novel targeted drugs are currently undergoing clinical trials. Given the recent US FDA approval of baricitinib and ritlecitinib, Janus kinase (JAK) inhibitors are a promising drug class for treating severe alopecia areata cases. This article will review the efficacy, safety, and tolerability of current treatments for alopecia areata, and will provide an overview of the emerging therapies that are leading the revolution in the management of this challenging disease.

Canine noninflammatory alopecia: An approach to its classification and a diagnostic aid

Noninflammatory alopecia is common in dogs and is a frequent cause to consult a veterinarian. It is also a common reason to take biopsies. Noninflammatory alopecia can be attributed to a decreased formation or cytodifferentiation of the hair follicle or the hair shaft in utero, resulting in congenital alopecia. Congenital alopecia often has a hereditary cause, and examples of such disorders are ectodermal dysplasias associated with gene variants of the ectodysplasin A gene. Noninflammatory alopecia may also be caused by impaired postnatal regeneration of hair follicles or shafts. Such disorders may have a clear breed predilection, and alopecia starts early in life. A hereditary background is suspected in those cases but has not been proven. They are referred to as follicular dysplasia although some of these disorders present histologically like a hair cycle disturbance. Late-onset alopecia is usually acquired and may be associated with endocrinopathies. Other possible causes are impaired vascular perfusion or stress. As the hair follicle has limited possible responses to altered regulation, and histopathology may change during the course of a disease, a detailed clinical history, thorough clinical examination including blood work, appropriate biopsy site selection, and detailed histological findings need to be combined to achieve a final diagnosis. This review aims to provide an overview about the known noninflammatory alopecic disorders in dogs. As the pathogenesis of most disorders is unknown, some statements are based on comparative aspects or reflect the authors' opinion.

Molecular and spatial landmarks of early mouse skin development

A wealth of specialized cell populations within the skin facilitates its hair-producing, protective, sensory, and thermoregulatory functions. How the vast cell-type diversity and tissue architecture develops is largely unexplored. Here, with single-cell transcriptomics, spatial cell-type assignment, and cell-lineage tracing, we deconstruct early embryonic mouse skin during the key transitions from seemingly uniform developmental precursor states to a multilayered, multilineage epithelium, and complex dermal identity. We identify the spatiotemporal emergence of hair-follicle-inducing, muscle-supportive, and fascia-forming fibroblasts. We also demonstrate the formation of the panniculus carnosus muscle (PCM), sprouting blood vessels without pericyte coverage, and the earliest residence of mast and dendritic immune cells in skin. Finally, we identify an unexpected epithelial heterogeneity within the early single-layered epidermis and a signaling-rich periderm layer. Overall, this cellular and molecular blueprint of early skin development-which can be explored at https://kasperlab.org/tools-establishes histological landmarks and highlights unprecedented dynamic interactions among skin cells.

Serum Zinc Concentration in Patients with Alopecia Areata

Alopecia areata is an autoimmune non-scarring disease in which the exact mechanism that induces loss of immune privilege is unknown. Zinc is important for DNA stability and repair mechanisms that are essential in maintaining normal hair growth. Zinc deficiency has been investigated as an important factor in many autoimmune diseases, and may have a possible role in the aetiopathogenesis of alopecia areata. This study included 32 patients with severe forms of alopecia areata, and 32 age- and sex-matched healthy controls. When comparing serum zinc levels in these 2 groups, statistically significantly lower zinc concentrations were found in the alopecia areata group (p = 0.017). Detected zinc deficiency was statistically more prevalent in patients with alopecia areata (p = 0.011). Evaluating patients with alopecia areata, a statistically significant negative correlation between serum zinc levels and severity of the disease was found (ρ = 0.006). The results indicate that zinc serum assessment is necessary in patients with alopecia areata. Low serum zinc levels were found to correlate with severity of alopecia areata. Given that most severe forms of alopecia areata are frequently most treatment-resistant, additional randomized control trials examining zinc supplementation are necessary to investigate its potential role in the restoration of hair follicles.

The histopathologic diagnosis of traction alopecia: An evidence-based model

BACKGROUND

Traction alopecia (TA) is common, but histopathologic criteria for TA have not been objectively defined.

OBJECTIVE

Determine whether the pauci-follicular unit (PFU) can be used as a diagnostic criterion for TA. Compared to a normal follicular unit (NFU), the PFU is a noninflamed follicular unit with an intact sebaceous gland but fewer than 2 follicles.

METHODS

A retrospective review of 25 cases of TA and 25 cases of "normal scalp" was performed. Data included all follicles (by size and phase), sebaceous glands, and total follicular units.

RESULTS

Comparing data (traction vs normal), we found a significantly higher number of PFUs in cases of TA (median 6 vs 0, P < .001), which can be used as a helpful and easily recognizable diagnostic tool in diagnosing cases of TA.

LIMITATIONS

Comparison to other forms of alopecia was not performed.

CONCLUSIONS

The number of PFUs in an alopecia biopsy can be used to establish the diagnosis of TA.

White hair in alopecia areata: Clinical forms and proposed physiopathologic mechanisms

Alopecia areata (AA) is a common form of nonscarring hair loss. It is believed to be a consequence of an immune-mediated stimulus, probably involving autoreactive T cells against antigens present in the hair follicle. The exact antigen is still unknown; however, some authors have proposed that melanogenesis-associated molecules might trigger autoimmunity. Although transient white hair regrowth is a common and well-known situation in AA, there are other types of white hair phenomena in this context, including permanent white hair regrowth, sparing of white hair in a patchy pattern, or sparing in a diffuse pattern, giving the appearance of the so-called overnight graying phenomena or canitis subita. In this review, we aim to describe the different clinical aspects of white hair in AA, as well as the proposed pathophysiologic mechanisms involved in this phenomena.

Application of Autologous Hair Transplantation Technique in Children with Cicatricial Alopecia

INTRODUCTION

Cicatricial alopecia not only affects the appearance of children's heads and faces but also their mental health in the long term. This study aims to explore the therapeutic characteristics and clinical effects of autologous hair transplantation technology in children with cicatricial alopecia.

METHODS

Children in our department who received autologous hair transplantation technology for cicatricial baldness of the scalp from February 2019 to October 2022 were collected. Their basic information was analyzed, and postoperative follow-up was conducted, including calculation of hair follicle survival rate, hair growth, complications, and an efficacy satisfaction survey given to the children's family members.

RESULTS

Thirteen children were included in this study (10 males and 3 females), aged from 4 years 1 month to 12 years 10 months, with an average age of 7 years 5 months. Two hundred to 2500 hair follicular units were extracted, with an average recipient area of 22.7 cm2, an average hair follicle unit density of 55.3 ± 9.1 per cm2, and an average hair/follicular unit (hair/FU) ratio of 1.75 ± 0.07. Thirteen children in this group were followed up for 6-12 months with the following treatment options: FUE (follicular unit extraction, 9 cases), FUT (follicular unit transplantation, 3 cases), and FUT combined with FUE (1 case). The average hair survival rate was 85.3%. Except for one child with temporary folliculitis, there were no complications. The GAIS score is divided into five levels: complete improvement (2 cases), obvious improvement (10 cases), partial improvement (1 case), no improvement (0 cases), and deterioration (0 cases). The patient satisfaction results included very satisfied (2 cases), mostly satisfied (10 cases), and dissatisfied (1 case).

CONCLUSION

Autologous hair transplantation technology is a safe and effective method for children with cicatricial alopecia.

Oral Teratoma with Hairy Polyp-Like Features: A Brief Report of a Rare Presentation

We present a 21-day-old female child presenting with a large oral epithelialized tumor implanted at the rhinopharynx and ethmoid plate through a cleft palate, associated with feeding and respiratory difficulties. The histopathological exam showed mature central adipose tissue, hair follicles, sebaceous glands, and neurovascular structures, lined by keratinized stratified squamous epithelium. Proliferative cartilaginous, glandular, lymphatic, bony, and immature myxoid tissue was seen at the posterior region and insertion. Despite the characterization of the tumor as a teratoma containing structures derived from the three embryonic leaflets, the anterior portion presented a microscopic bigeminal pattern fully compatible with hairy polyp.

Dynamic evaluation of pathological changes in a mouse acne model by optical imaging technology

Acne vulgaris is a disorder of the pilosebaceous unit that is primarily caused by hyperseborrhoea, colonization with Propionibacterium acnes, hyperkeratosis and an inflammatory response. Existing pharmacodynamic assessment methods primarily focus on a single causative factor at a certain time point, making it difficult to assess multiple factors simultaneously in real time. Therefore, it is crucial to establish a dynamic and nondestructive method for the assessment of acne in vivo. This study utilized four-dimensional optical imaging techniques to assess the pathogenic factors and pathological progression of acne. LSCI was employed to measure blood flow; TPEF was used to observe inflammatory changes (NAD(P)H) in epidermal granular layer cells and structural changes in collagen fibres in the dermal layer. Additionally, the dermatoscope was used to investigate the micro-characterization of the lesions. We observed that the epidermis in the lesion area was thickened, hair follicles were keratinized, and there was obvious inflammation and blood flow aggregation by optical imaging technology. Based on these findings, the pathological progression of this acne model could be divided into the inflammation phase, accompanied by bacterial colonization, and the reparative phase. These results provide a new perspective for the assessment of acne and offer an experimental basis for the selection of precise drugs for clinical use.

Secondary alopecia induced by aesthetic procedures: An unrecognized potential complication

Surgical facelifts and noninvasive techniques such as mesotherapy, hyaluronic fillers and botulinum toxin, among other procedures are widely used nowadays to reverse skin ageing and achieve rejuvenation effects. Secondary alopecia due to cosmetic procedures is a rare side effect and is poorly described in the literature. The mechanisms in which hair loss develops after an aesthetical procedure or surgical technique are not well known. The development of secondary scarring alopecia or non-scarring alopecia depends upon the interaction between different external factors, the individual host response and the extent of damage to the hair follicle anatomy. Current knowledge hints at the type of substance used, pressure to hair structures and vasculature due to the materials used, previously unknown or unaware hair disorder, and poor surgical techniques to be the main factors contributing to the development of secondary alopecia. Physicians and patients must be aware of all the substances used for the procedures and be attentive to any change in hair density or hair loss. Clinicians must have a low threshold to take biopsies if the risk of scarring alopecia may occur. Herein, we review the clinical, trichoscopic, histopathological findings and potential pathophysiological mechanisms of hair loss due to different aesthetic procedures.

Diagnosis and differential diagnosis of tertiary androgenetic alopecia with severe alopecia areata based on high-resolution MRI

BACKGROUND AND AIM

No previous study investigated the anatomical changes of the scalp and hair follicles between tertiary androgenetic alopecia and severe alopecia areata using high-resolution magnetic resonance imaging (HR-MRI). This study aimed to explore the value of HR-MRI in assessing alopecia.

MATERIALS AND METHODS

Forty-eight people were included in this study. The imaging indicators of the vertex and occipital scalp were recorded and compared. The logistic regression model was developed for the indicators that differed between tertiary androgenetic alopecia and severe alopecia areata. The receiver-operating characteristic (ROC) curve was used to assess the diagnostic efficacy of the model for tertiary androgenetic alopecia and severe alopecia areata.

RESULTS

At the vertex, the thickness of the subcutaneous tissue layer, follicle depth, relative follicle depth, total number of follicles within a 2-cm distance, and number of strands reaching the middle and upper third of the subcutaneous fat layer within a 2-cm distance were statistically different between patients with tertiary androgenetic alopecia, those with severe alopecia areata, and healthy volunteers (p < 0.05). The logistic regression model suggested that the subcutaneous tissue layer thickness was important in discriminating tertiary androgenetic alopecia from severe alopecia areata. The ROC curve showed that the area under the curve, sensitivity, specificity, and best cutoff values of the subcutaneous tissue layer were 0.886, 94.4%, 70%, and 4.31 mm, respectively.

CONCLUSIONS

HR-MRI can observe the changes in anatomical structures of the scalp and hair follicles in patients with alopecia. HR-MRI can be applied to the differential diagnosis of tertiary androgenetic alopecia and severe alopecia areata.

A malignant proliferating trichilemmal cyst arising on the elbow of a man: A case report and review of the literature

INTRODUCTION

Trichilemmal cysts (TCs) are common benign cysts that form from the hair follicles in the skin. Proliferating trichilemmal cysts (PTCs) are rare types of TCs characterized by rapid cellular proliferation. Malignant transformation of PTC (MPTC) is a rare adnexal tumor that account for <0.1% of all skin cancers. TCs and PTCs are benign tumors; however, MPTCs grow rapidly and are prone to metastasis.

CASE PRESENTATION

A 77-year-old man was referred to our hospital with a solitary pinkish mass on his left elbow. Trichilemmal carcinoma arising from a PTC was confirmed through excisional biopsy, and wide excision was performed. One month postoperatively, a cystic mass was observed and was suspected to have local recurrence; however, bursitis was confirmed after excisional biopsy. After 1 year of follow-up, the patient maintained an improvement without recurrence or any other surgical complications.

CONCLUSIONS

In addition to being a very rare disease, MTPC occurred in the elbow of a man who does not fit the general etiology; therefore, it is considered an interesting case, and we report this case for academic contribution.

Melanocytic Matricoma With Atypical Histopathological Features: A Case Report of an Extremely Rare Entity and Review of the Literature

ABSTRACT

Melanocytic matricoma with atypical features is a rare, biphasic adnexal neoplasm displaying hair matrix differentiation, with only 3 reported cases worldwide. Generally, the lesion comprised a solid matrical and supramatrical cell proliferation, admixed with intermediate cell aggregates with sparse anucleated "shadow cells" and a prominent pigmented melanocytic hyperplasia. We report the case of a 78-year-old man with a slow-growing crusted lesion on the frontal left scalp, which in a matter of 1-2 months became a 0.6 cm well-defined, black purplish exophytic nodule. Histopathologically, the lesion presented a well-circumscribed border with a nodular dermal growth pattern, presenting different architectural features varying from benign pilomatricoma-like changes to atypical features such as moderate-to-high nuclear pleomorphism in both basaloid (matrical/supramatrical) and epidermal (keratinous) components. Strong nuclear and cytoplasmic positivity for β-catenin was observed in matrical cells, whereas prominent cytoplasmic membrane positivity for Melan-A in dendritic melanocytes. Owing to the evidence of atypical cytological features, we propose the "atypical/borderline" category of melanocytic matricoma as part of a possible spectrum among matrical neoplasms. Pathologists should be aware of any atypical histopathological features while reporting cases due to their potential malignant transformation.

Clinical and dermatoscopic features of temporal triangular alopecia in infants

OBJECTIVE

To summarize the clinical and dermatoscopic features of temporal triangular alopecia in infants and explore the clinical significance of dermatoscopy in the diagnosis of triangular alopecia temporalis in infants.

METHODS

A retrospective analysis was performed on 20 children with temporal triangular alopecia diagnosed in the dermatology clinic of Tianjin Children's Hospital from January 2015 to December 2021. Dermatoscopy was performed on all children, and images were collected.

RESULTS

The clinical features of 20 children were 15 males and five females, all of which were born immediately after birth; There were eight cases (40%) in the left temporal region, 10 cases (50%) in the right temporal region, one case (5%) in the head region, and one case (5%) in the occipital region; 19 cases were single (95%), one case was multiple (5%); There were 21 skin lesions, 15 triangular lesions (71.4%), four quasi-circular lesions (19%), and two lance-shaped lesions (9.5%). Trichoscopic features: The hair follicle opening in all skin lesions is normal, and the hair follicle opening can be seen with fluffy hair (vellus hair). The vellus hair is evenly distributed, and the length is diverse (both short and long vellus hair exist in the same hair loss area). There are 14 cases of white vellus hair (70%), five cases of white spots (25%), one case of honeycomb pigment pattern (5%), and one case of vascular dilation pattern (5%).

CONCLUSION

Temporal triangular alopecia in infants has typical clinical and dermatoscopic characteristics, and the dermatoscopy can provide clinical basis for its diagnosis and differential diagnosis.

Folliculitis Decalvans Has a Heterogeneous Microbiological Signature and Impaired Immunological Response

BACKGROUND

Folliculitis decalvans (FD) is a rare primary neutrophilic scarring alopecia whose etiology has not been completely elucidated yet.

OBJECTIVE

The aim of the study was to determine if the follicular microbiota residing in FD-affected hair follicles had a distinct microbiological signature and if an aberrant immune response was present in the pathogenesis of FD.

METHODS

We conducted a cross-sectional study of 10 patients affected by FD. Trichoscopy-guided follicular biopsies were taken from affected and healthy scalp to identify the follicular microbiome using next-generation sequencing. We searched for microbiological biomarkers of FD-affected follicles using the linear discriminant analysis (LDA) effect size (LEfSe) tool. Additionally, peripheral blood mononuclear cells were obtained, and their cytokine production was quantified after incubation with pathogen-associated molecular patterns isolated from patients' biopsies and compared with healthy controls.

RESULTS

β-diversity analysis showed statistically significant differences regarding bacteria comparing follicular microbiota of healthy and FD-affected hairs. Ruminococcaceae, Agathobacter sp., Tyzzerella sp., and Bacteriodales vadin HA21 family were good predictors of disease status. IL-10, TNF-α, and IL-6 levels were significantly decreased in patients after incubation with various strains of bacteria compared with controls.

CONCLUSION

FD hair follicles have a specific heterogenous follicular bacterial microbiota signature. Additionally, these patients seem to have an impaired immunological response.

[Morphologial changes in the hair follicle and hair shaft in old age.]

The work is based on the results of a microscopic examination of 46 men and 50 women who were examined at the medical center for the treatment of hair and skin in the period 2022-2023. Depending on the age of the subjects, they were divided into two groups. The first group included 52 people (25 men and 27 women) of young age (21-35 years old). The second group consisted of 44 people (21 men and 23 women) of senile age (75-86 years old). Hair sampling was performed in the temporal region of the head by combing out the hair that had already fallen out with a comb (they did not pull it out of the skin!). The sample of this study consisted of conditionally healthy individuals of the Slavic phenotype. The width of the hair follicle and the hair shaft were calculated. The results of this lifetime comparative analysis of the linear dimensions of the hair follicle and the hair shaft in the temporal region in persons of both sexes of young and old age allow us to expand the understanding of the features of their age-related changes, and further continue detailed study, since new knowledge is necessary for the development of modern methods for the prevention of age-associated pathologies of the scalp.

Keratinic amyloid deposition in canine hair follicle tumors

Keratinic primary localized cutaneous amyloidosis is a disease in humans; however, no similar condition has been reported in animals. This study aimed to investigate cutaneous keratinic amyloid deposition in dogs and elucidate its etiology. Canine hair follicle tumor tissues were histopathologically analyzed. Immunohistochemistry and mass spectrometry-based proteomic analyses were performed to identify precursor protein candidates. Structural prediction and in vitro fibrillization analyses were conducted to determine the amyloidogenic region and gene sequencing analysis was performed to assess mutations. Of the 266 samples, 16 had amyloid deposition. Amyloid deposits were found in the stroma of tumors and in the margins of keratin debris and around normal hair follicles. Cytokeratin 5 (CK5) was identified as a precursor protein candidate. C-terminal truncation of CK5 was observed in amyloid deposits, and the truncation sites varied depending on the deposition pattern. There was a significantly higher incidence of amyloid deposition in Shiba dogs, and CK5 amino acid polymorphisms were identified in these dogs. A part of the C-terminal region of both canine and human CK5 exhibited highly amyloidogenic properties in vitro. This study revealed the existence of cutaneous keratinic amyloid deposition in animals and identified CK5 as an amyloid precursor protein, providing novel insights into understanding the etiology of cutaneous amyloidosis.

Segmental basaloid follicular hamartomas derive from a post-zygotic SMO p.L412F pathogenic variant and express hair follicle development-related proteins in a pattern that distinguish them from basal cell carcinomas

Basaloid follicular hamartomas (BFH) are benign small basaloid skin tumors that can present as solitary or multiple lesions. Congenital BFH lesions arranged in a segmental distribution have been described, suggesting they derive from a somatic post-zygotic mutational event. Previously, BFH were described in Happle-Tinschert syndrome, which results from a post-zygotic SMO variant and is characterized by segmental BFH with variable involvement of the teeth, skeleton, and central nervous system. Here, we describe two patients with isolated segmental BFH and no systemic involvement. Paired whole exome sequencing of BFH and normal tissue revealed a pathogenic SMO c.1234 C>T, p.L412F variant restricted to BFH tissue. We characterized the proliferation index and expression of Hedgehog and Wnt/beta-catenin pathway related proteins in segmental BFH compared to sporadic basal cell carcinomas (BCCs) and found that segmental BFH had a lower proliferation index. Although segmental BFH expressed a similar level of Gli-1 compared to BCCs, levels of LEF-1 and SOX-9 expression in BFH were weaker for both and patchier for LEF-1. Our results show that a somatic SMO activating variant causes segmental BFH. Since these patients are prone to developing BCCs, differences in SOX9, LEF1, and Ki-67 expression can help distinguish between these two basaloid lesions.

The efficacy of LED microneedle patch on hair growth in mice

Light penetration depth in the scalp is a key limitation of low-level light therapy for the treatment of androgenetic alopecia (AGA). A novel light emitting diode (LED) microneedle patch was designed to achieve greater efficacy by enhancing the percutaneous light delivery. The study aimed to investigate the efficacy and safety of this device on hair growth in mice. Thirty-five male C57BL/6 mice which their dorsal skin was split into upper and lower parts to receive either LED irradiation alone or LED irradiation with a microneedle patch. Red (629 nm), green (513 nm), and blue light (465 nm) at an energy dose of 0.2 J/cm² were applied once daily for 28 days. Outcomes were evaluated weekly using digital photographs. Histopathological findings were assessed using a 6 mm punch biopsy. A significant increase in hair growth was observed in the green light, moderate in the red light, and the lowest in the blue light group. The addition of the microneedle patch to LED irradiation enhanced greater and faster anagen entry in all the groups. Histopathology showed an apparent increase in the number of hair follicles, collagen bundles in the dermis, angiogenesis, and mononuclear cell infiltration after treatment with the green-light LED microneedle patches. No serious adverse effects were observed during the experiment. Our study provides evidence that the newly developed green-light LED microneedle patch caused the optimal telogen-to-anagen transition and could lead to new approaches for AGA. Microneedle stimulation may aid percutaneous light delivery to the target hair follicle stem cells.

Folliculosebaceous Cystic Hamartoma Arising in Miescher-Type Melanocytic Nevi

ABSTRACT

Folliculosebaceous cystic hamartoma (FSCH) is a rare cutaneous hamartoma consisting of dilated folliculosebaceous units associated with mesenchymal elements. Ansai et al reported that distinctive features of Miescher-type melanocytic nevi (MMCNs) accompanied 4.6% of FSCH; however, there have been no data about how often FSCH features accompany MMCNs. In this study, we used 7829 cases that had been histopathologically diagnosed as MMCNs of the face, neck, and scalp at the Department of Dermatopathology, Nippon Medical School Musashi Kosugi Hospital and observed whether features of FSCH accompanied them. Of the resected MMCNs, 274 of 7829 (3%) were accompanied by features of FSCH. The nose was the most common resection site, followed by the eyebrow area, ear, and cheek. The coexistence rate for the nevi on the nose and features of FSCH was as high as 10%-20%, and its rate increased with age. We found that FSCH appears mostly in seborrheic areas, such as the nose and cheek, which are rich in normal sebaceous glands. This suggests that nevi, especially on and around the nose, may induce FSCH or similar lesions.

Innate type 2 immunity controls hair follicle commensalism by Demodex mites

Demodex mites are commensal parasites of hair follicles (HFs). Normally asymptomatic, inflammatory outgrowth of mites can accompany malnutrition, immune dysfunction, and aging, but mechanisms restricting Demodex outgrowth are not defined. Here, we show that control of mite HF colonization in mice required group 2 innate lymphoid cells (ILC2s), interleukin-13 (IL-13), and its receptor, IL-4Ra-IL-13Ra1. HF-associated ILC2s elaborated IL-13 that attenuated HFs and epithelial proliferation at anagen onset; in their absence, Demodex colonization led to increased epithelial proliferation and replacement of gene programs for repair by aberrant inflammation, leading to the loss of barrier function and HF exhaustion. Humans with rhinophymatous acne rosacea, an inflammatory condition associated with Demodex, had increased HF inflammation with decreased type 2 cytokines, consistent with the inverse relationship seen in mice. Our studies uncover a key role for skin ILC2s and IL-13, which comprise an immune checkpoint that sustains cutaneous integrity and restricts pathologic infestation by colonizing HF mites.

Role of hair follicles in the pathogenesis of arsenical-induced cutaneous damage

Arsenical vesicants cause skin inflammation, blistering, and pain. The lack of appropriate animal models causes difficulty in defining their molecular pathogenesis. Here, Ptch1+/- /C57BL/6 mice were employed to investigate the pathobiology of the arsenicals lewisite and phenylarsine oxide (PAO). Following lewisite or PAO challenge (24 h), the skin of animals becomes grayish-white, thick, leathery, and wrinkled with increased bi-fold thickness, Draize score, and necrotic patches. In histopathology, infiltrating leukocytes (macrophages and neutrophils), epidermal-dermal separation, edema, apoptotic cells, and disruption of tight and adherens junction proteins can be visualized. PCR arrays and nanoString analyses showed significant increases in cytokines/chemokines and other proinflammatory mediators. As hair follicles (HFs), which provide an immune-privileged environment, may affect immune cell trafficking and consequent inflammatory responses, we compared the pathogenesis of these chemicals in this model to that in Ptch1+/- /SKH-1 hairless mice. Ptch1+/- /SKH-1 mice have rudimentary, whereas Ptch1+/- /C57BL/6 mice have well-developed HFs. Although no significant differences were observed in qualitative inflammatory responses between the two strains, levels of cytokines/chemokines differed. Importantly, the mechanism of inflammation was identical; both reactive oxygen species induction and consequent activation of unfolded protein response signaling were similar. These data reveal that the acute molecular pathogenesis of arsenicals in these two murine models is similar.

Microneedling combined with compound betamethasone in treatment of severe alopecia areata: A case report

Alopecia areata (AA) is a common inflammatory, non-cicatricial hair loss. At present, it is considered that its pathogenesis is an autoimmune disease specific to hair follicle organs mediated by T cells under the combined action of genetic and environmental factors. Treatment is challenging for children with severe AA who are resistant or intolerant to conventional treatment.Here, we treated a 3-year-old child with severe AA with microneedling combined with compound betamethasone. After 6 months of treatment, the patient’s condition was significantly improved, and most of the primary hair loss areas had hair regeneration.

Bulboma: A Benign Keratosis With Differentiation Toward the Lower Segment of the Hair Follicle

ABSTRACT

Bulboma is an appellation proposed to designate a distinctive solitary keratosis exhibiting differentiation toward the bulb of the lower segment of the hair follicle. Bulboma is composed of a papillated proliferation of epithelial cells beneath which is a broad front of interconnected follicular papillae. Overlying these coalescing follicular papillae are follicular germinative cells ascending into matrical cells and supramatrical cells. Cells demonstrating differentiation toward Huxley's and Henle's layer of the inner root sheath at the level of the bulb are present including strikingly bright eosinophilic trichohyalin granules and the blue-grey corneocytes of the stem. There is overlying hypergranulosis and orthokeratosis. The clinical and histopathological findings in 4 cases of bulboma, a rare, benign solitary keratosis are presented.

Follicular Melanocytes in Frontal Fibrosing Alopecia: An Immunohistochemical Study With Trichoscopic Correlation

BACKGROUND

Frontal fibrosing alopecia (FFA) is a scarring alopecia that affects the frontotemporal hairline. Clinically, it may develop with cutaneous hypopigmentation of the affected areas, which has been associated with a reduction in the epidermal melanocyte count. In trichoscopy, peripilar white halos can be observed, which have been associated with fibrosis in other scarring alopecias.

OBJECTIVE

To evaluate the trichoscopic, histopathological and immunohistochemical characteristics of the peripilar white halos in FFA patients.

MATERIALS AND METHODS

We conducted a descriptive cross-sectional study that included 12 patients with FFA presenting peripilar white halos. Two 2-mm punch trichoscopy-guided biopsies were performed in all patients, one fragment for vertical section and another for horizontal section. The vertical sections were stained with Fontana-Mason and Melan-A.

RESULTS

On trichoscopic examination, peripilar white halos ≤ 1 mm in size were observed on the affected scalp. In vertical sections, a reduction in basal melanin pigmentation and a decrease in the melanocyte count in the upper segment of the hair follicle were observed with Fontana-Masson staining and Melan-A immunostaining, respectively.

LIMITATIONS

The small sample size and absence of a control group.

CONCLUSION

This study shows follicular melanocyte involvement in FFA, and this finding may be associated with the peripilar white halos observed in trichoscopy.

Molecular pathology of skin adnexal tumours

AIMS

Tumours of the cutaneous adnexa arise from, or differentiate towards, structures in normal skin such as hair follicles, sweat ducts/glands, sebaceous glands or a combination of these elements. This class of neoplasms includes benign tumours and highly aggressive carcinomas. Adnexal tumours often present as solitary sporadic lesions, but can herald the presence of an inherited tumour syndrome such as Muir-Torre syndrome, Cowden syndrome or CYLD cutaneous syndrome. In contrast to squamous cell carcinoma and basal cell carcinoma, molecular changes in adnexal neoplasia have been poorly characterised and there are few published reviews on the current state of knowledge.

METHODS AND RESULTS

We reviewed findings in peer-reviewed literature on molecular investigations of cutaneous adnexal tumours published to June 2021.

CONCLUSIONS

Recent discoveries have revealed diverse oncogenic drivers and tumour suppressor alterations in this class of tumours, implicating pathways including Ras/MAPK, PI3K, YAP/TAZ, beta-catenin and nuclear factor kappa B (NF-κB). These observations have identified novel markers, such as NUT for poroma and porocarcinoma and PLAG1 for mixed tumours. Here, we provide a comprehensive overview and update of the molecular findings associated with adnexal tumours of the skin.

Eruptive Necrotizing Infundibular Crystalline Folliculitis: An Expression of an Abortive Sebaceous Follicular Repair Pathway Linked to Committed Infundibular Stem Cells?

ABSTRACT

Necrotizing infundibular crystalline folliculitis is a rare entity, which is a distinctive clinical and histopathological entity. Eruptive yellow waxy umbilicated folliculocentric plugs clinically correspond to pale crystalline filaments embedded in an amorphous sebum-rich material. Remarkably, only the superficial infundibular ostia remain, and the distended cavity is devoid of a follicular or sebaceous gland remnant. The pathogenesis of this enigmatic event remains to be established. The emergence of necrotizing infundibular crystalline folliculitis (NICF) as a paradoxical side effect of antitumor inhibitors epidermal growth factor receptor vascular endothelial growth factor and more recently programmed death-1 represents the expression of altered molecular pathways that underpin the pathogenesis of NICF. To explore these pathways, it is necessary to explore the hierarchy of follicular stem cells, particularly the potential role of committed infundibular stem cells that play a key role in wound healing. Committed infundibular stem cells are closely linked to the sebaceous gland stem cell axis, and this has relevance in the process of homeostatic repair of sebaceous follicles in the wake of folliculitis. The unscheduled modulation of this infundibular homeostatic sebaceous repair axis by epidermal growth factor receptor vascular endothelial growth factor, and programmed death-1 may lead to an aberrant outcome with metaplasia of infundibular keratinocytes to sebocytes. In the absence of sebaceous gland differentiation, these metaplastic infundibular sebocyte cells would lead to the consumption and loss of the infundibulum as a result of holocrine sebum production. This conceptual pathogenic pathway for NICF is constructed by incorporating recent advances in the fields of follicular stem cells, wound repair, follicular homeostasis, regulatory T cells, and molecular pathways linked to the biologicals inducing NICF.

T-Cell-Driven Fibroinflammation Inducing Follicular Dedifferentiation in Alopecia Areata and IgG4-Modified Disease

ABSTRACT

The definition of IgG4-related diseases incorporates a broad range of systemic diseases particularly a subset dominated by fibroinflammation. CD4+cytotoxic T cells have emerged as the major driving force for the fibroinflammation, and the pathogenetic role of IgG4 still remains to be determined. Cutaneous involvement is uncommon and is not well defined as elevated tissue IgG4 plasma cells are not a specific marker and prominent cutaneous fibroinflammation is often absent in cutaneous disease. We report the case of a patient with longstanding alopecia universalis and severe atopic dermatitis who presented with diffuse induration and mottled dyspigmentation of his scalp. Multiple scalp biopsies revealed diffuse interfollicular fibroinflammation and IgG4 plasma cells with induction of distinctive dedifferentiated follicles not seen in alopecia areata. This complex case may provide insight into the role of specific subsets of T cells not only in respect to the fibroinflammation linked to IgG4-related diseases but also the capacity to modify disease, follicular stem cell activation, immune privilege, cytotoxicity in alopecia areata, and the presence of atopy that may have contributed to the pathogenesis of this case.

Trichoblastoma: A Consecutive Series of 349 Sporadic Cases Analyzed by Ackerman Subtypes

ABSTRACT

Trichoblastoma (TB) is a benign biphasic follicular neoplasm with differentiation toward the germinative cells and a specific follicular mesenchyme. We subtyped 349 sporadic TB according to a classification proposed by Ackerman. Two hundred forty-six (246/349, 70.5%) neoplasms were comprised of mixed subtypes. TB composed exclusively of a single pattern was less common (103/349, 29.5%). The most common pure subtype was cribriform TB followed by small nodular TB. Twelve cases (12/349, 3.4%) had unique features and are reported herein as novel histopathologic subtypes of the neoplasm.

Disruption of the endopeptidase ADAM10-Notch signaling axis leads to skin dysbiosis and innate lymphoid cell-mediated hair follicle destruction

Hair follicles (HFs) function as hubs for stem cells, immune cells, and commensal microbes, which must be tightly regulated during homeostasis and transient inflammation. Here we found that transmembrane endopeptidase ADAM10 expression in upper HFs was crucial for regulating the skin microbiota and protecting HFs and their stem cell niche from inflammatory destruction. Ablation of the ADAM10-Notch signaling axis impaired the innate epithelial barrier and enabled Corynebacterium species to predominate the microbiome. Dysbiosis triggered group 2 innate lymphoid cell-mediated inflammation in an interleukin-7 (IL-7) receptor-, S1P receptor 1-, and CCR6-dependent manner, leading to pyroptotic cell death of HFs and irreversible alopecia. Double-stranded RNA-induced ablation models indicated that the ADAM10-Notch signaling axis bolsters epithelial innate immunity by promoting β-defensin-6 expression downstream of type I interferon responses. Thus, ADAM10-Notch signaling axis-mediated regulation of host-microbial symbiosis crucially protects HFs from inflammatory destruction, which has implications for strategies to sustain tissue integrity during chronic inflammation.

Cutaneous Lymphadenoma Is a Distinct Trichoblastoma-like Lymphoepithelial Tumor With Diffuse Androgen Receptor Immunoreactivity, Notch1 Ligand in Reed-Sternberg-like Cells, and Common EGFR Somatic Mutations

The term "cutaneous lymphadenoma" was coined in this journal for an unusual lymphoepithelial cutaneous adnexal neoplasm, possibly with immature pilosebaceous differentiation. Some authors further proposed that cutaneous lymphadenoma was an adamantinoid trichoblastoma. However, although a hair follicle differentiation is widely accepted, the fact that this is a lymphoepithelial tumor is not appropriately explained by the trichoblastoma hypothesis. Our goal was to further clarify the phenotypic and genotypic features of cutaneous lymphadenoma in a series of 11 cases. Histologically, a lobular architecture surrounded by a dense fibrous stroma was present in all cases. The lobules were composed of epithelial cells admixtured with small lymphocytes and isolated or clustered large Reed-Sternberg-like (RS-L) cells. The epithelial cells were diffusely positive for the hair follicle stem cell markers CK15, PHLDA1, and for androgen receptor. No immunostaining for markers of sebaceous differentiation was found. Intraepithelial lymphocytes were predominantly CD3+, CD4+, FoxP3+ T cells. RS-L cells showed both strong Jagged-1 and Notch1 cytoplasmic immunostaining. Androgen-regulated NKX3.1 nuclear immunostaining was present in a subset of large intralobular cells in all cases. Double immunostaining showed coexpression of NKX3.1 and CD30 in a subset of RS-L cells. No immunostaining for lymphocytic or epithelial markers was present in RS-L cells. EGFR, PIK3CA, and FGFR3 somatic mutations were found by next-generation sequencing in 56% of the cases. We consider that cutaneous lymphadenoma is a distinct benign lymphoepithelial tumor with androgen receptor and hair follicle bulge stem cell marker expression, RS-L cell-derived Notch1 ligand, and common EGFR gene mutations.

Induction of alopecia areata in C3H/HeJ mice using cryopreserved lymphocytes

BACKGROUND

Alopecia areata (AA) is an autoimmune disease resulting in non-scarring hair loss. Animal models are useful means to identify candidates for therapeutic agents. The C3H/HeJ mouse AA model induced via transferring cultured lymphoid cells isolated from AA-affected mice is widely used for AA research. However, this conventional method requires the continuous breeding of AA mice.

OBJECTIVE

We aimed to establish a new method to generate AA model using the transfer of cryopreserved cells, which allows the rapid induction of a large number of AA mice when needed.

METHODS

We cryopreserved lymph node cells soon after isolation from AA-affected mice and injected thawed-cultured cells into recipient mice. H&E staining, immunohistochemical staining, quantitative real-time PCR and ELISA were conducted to identify pathological characteristics. Flow cytometry was performed to reveal the profile of transferred cells.

RESULTS

More than 90 % of recipient mice developed AA-like hair loss and showed inflammatory cell infiltration around anagen hair follicles, markedly increased mRNA expressions of interferon-γ, CXCL11, and granzyme B, and elevated interferon-α protein levels in the skin compared with naïve mice. Higher percentages of effector memory T cells and dendritic cells in transferred cells resulted in a higher incidence of AA.

CONCLUSION

This is the first report to establish a method for generating AA mice using cryopreserved lymphocytes. These AA mice have similar pathological characteristics to AA mice generated with the conventional method and AA patients. This convenient and reproducible method is expected to be valuable for AA study.

Histologic features of hair follicle neoplasms and cysts in dogs and cats: a diagnostic guide

Hair follicle neoplasms occur in many different species, including humans. In domestic animals, they are most common in dogs. Most hair follicle tumors are benign, but malignant neoplasms can also occur. To diagnose hair follicle neoplasms, a thorough knowledge of follicular anatomy is important, given that follicular tumors are classified according to the differentiation pattern seen in the corresponding part of the normal hair follicle. This review focuses on the key diagnostic features of hair follicle tumors and follicular cysts in dogs and cats.

Histopathological Differentiation of Antemortem and Postmortem Electrical Burn Mark Produced by Low Voltage

ABSTRACT

The study was undertaken to differentiate antemortem electrical (AME) and postmortem electrical (PME) burn marks with the help of histopathology. The electrical burn mark was produced on 25 dead bodies. Alongside 25 cases of electrocution deaths were included for comparison. Slides were prepared and stained with hematoxylin-eosin stains. Intraepidermal and subepidermal separation; coagulative necrosis of the epidermis; nuclear elongation and hyperchromasia of epidermal cells; homogenization of the dermis; nuclear elongation and hyperchromasia of hair follicles, sweat glands, sebaceous glands, and blood vessel endothelium were studied for histopathological changes and graded. The findings of the study suggest that the histopathological changes in electrical burn marks are due to the physical effect of heat produced by the electric current. The classical histopathological features of electrical burn mark cannot differentiate between AME and PME burn marks. However, careful evaluation of grading of the dermal changes can be helpful in differentiating AME and PME burn marks. Highest grade of dermal thickness homogenization and highest grade of nuclear elongation of dermal appendages were significantly more in the antemortem electrical burn marks than PME burn marks.

Hair follicle dystrophy in a litter of domestic cats resembling lanceolate hair mutant mice

BACKGROUND

A new congenital hair-shaft abnormality resembling the lanceolate hair phenotype of rodents is described in a litter of four domestic short hair (DSH) cats. Data relating to hair shaft and follicle disorders remain scarce in veterinary medicine.

OBJECTIVES

To describe and compare structural abnormalities in these cats with other hair dystrophies in cats and other mammals.

ANIMALS

A DSH cat litter with progressive noninflammatory alopecia.

METHODS AND MATERIALS

Histopathological evaluation, scanning and transmission electron microscopy, and X-ray based element analysis defined the hair and skin changes in cats born with alopecia. Findings were compared to archival data from normal cats and lanceolate hair (Dsg4lahJ ) and Keratin 75 (Krt75tm1Der ) mutant mice.

RESULTS

Light and scanning electron microscopy of the hairs revealed lance- or spear-head shaped defects of the hair tip. Histological findings were swollen hair shafts, initially above the hair bulb matrix and later found in the distal parts of the telogen hair follicles, similar to those observed in Dsg4lahJ Krt75tm1Der mutant mice. Transmission electron microscopy of the hair shaft and hair follicles showed a loss in the normal structure of the guard hairs in the alopecic cats. There was a statistically significant decrease in sulfur content just below the defects in the hair shafts (trichothiodystrophy).

CONCLUSION AND CLINICAL IMPORTANCE

A rare form of congenital alopecia resulting in follicular dystrophy is described in cats which is similar to hair follicle and hair-shaft changes reported in several mutant mouse strains with single gene mutations in adhesion molecules or keratin genes.

Telogen Effluvium - a review of the science and current obstacles

Telogen effluvium (TE) is a common cause of diffuse non-scarring hair loss that is usually precipitated by physiological stress such as childbirth or sudden weight loss. Despite its high rate of remission, this phenomenon of sudden excessive hair loss can be very worrisome and upsetting for affected individuals and may significantly impact their quality of life. Due to the multifactorial causes and precipitants of TE, it is often challenging to diagnose and manage. Further, the mechanisms through which physiological stress influences the human hair cycle is unknown, and there are no targeted treatments for the management of TE. This review will describe the approach in making a diagnosis of TE, summarize the latest developments made in understanding the mechanisms of TE, outline the treatments tried, and recommend ways for advancing the study of this dermatological condition.

Dysfunction of Hair Follicle Mesenchymal Progenitors Contributes to Age-Associated Hair Loss

Skin aging is accompanied by hair loss due to impairments in hair follicle (HF) epithelial progenitor cells and their mesenchymal niche. This inductive mesenchyme, called dermal papilla (DP), undergoes progressive cell loss and eventual miniaturization that contributes to HF pathogenesis. Using laser ablation and fate mapping, we show that HF dermal stem cells (hfDSCs) reconstitute the damaged DP and maintain hair growth, suggesting that hfDSC dysfunction may trigger degeneration of the inductive niche. Fate mapping over 24 months revealed progressive hfDSC depletion, and in vivo clonal analysis of aged hfDSCs showed impaired self-renewal and biased differentiation. Single-cell RNA-seq confirmed hfDSCs as a central precursor, giving rise to divergent mesenchymal trajectories. In aged skin, hfDSCs exhibited senescent-like characteristics, and senescence-associated secretory phenotypes were identified in the aging HF mesenchyme. These results clarify fibroblast dynamics within the HF and suggest that progressive dysfunction within the mesenchymal progenitor pool contributes to age-related hair loss.

DNA Damage Promotes Epithelial Hyperplasia and Fate Mis-specification via Fibroblast Inflammasome Activation

DNA crosslinking agents are commonly used in cancer chemotherapy; however, responses of normal tissues to these agents have not been widely investigated. We reveal in mouse interfollicular epidermal, mammary and hair follicle epithelia that genotoxicity does not promote apoptosis but paradoxically induces hyperplasia and fate specification defects in quiescent stem cells. DNA damage to skin causes epithelial and dermal hyperplasia, tissue expansion, and proliferation-independent formation of abnormal K14/K10 dual-positive suprabasal cells. Unexpectedly, this behavior is epithelial cell non-autonomous and independent of an intact immune system. Instead, dermal fibroblasts are both necessary and sufficient to induce the epithelial response, which is mediated by activation of a fibroblast-specific NLRP3 inflammasome and subsequent IL-1β production. Thus, genotoxic agents that are used chemotherapeutically to promote cancer cell death can have the opposite effect on wild-type epithelia by inducing, via a non-autonomous IL-1β-driven mechanism, both hyperplasia and stem cell lineage defects.