Skin Lesions Research Articles

Metagenomic Next-Generation Sequencing as an Effective Diagnostic Tool for Talaromycosis in HIV-Negative Patients.

The diagnosis of Talaromyces marneffei infection in HIV-negative patients remains challenging. There is an urgent need for rapid and convenient methods to diagnose this complicated disease. The aim of this study was to evaluate the diagnostic efficiency of metagenomic next-generation sequencing (mNGS) for talaromycosis in non-HIV-infected patients by comparing mNGS with traditional microbial culture. In total, 66 samples from 57 patients were analyzed via both mNGS and microbial culture. The ROC curve showed a sensitivity for mNGS of 97.22%, which was greater than that of microbial culture (61.11%). Samples from the respiratory tract, infectious skin lesions, and lymph nodes are recommended as routine samples for talaromycosis detection via mNGS. Furthermore, mNGS significantly reduced the diagnostic time compared to microbial culture. Overall, our study demonstrated that mNGS is a promising tool for rapid and accurate pathogenic detection in HIV-negative patients with talaromycosis.

Vision transformer and CNN-based skin lesion analysis: classification of monkeypox

AbstractMonkeypox is an important health problem. Rapid diagnosis of monkeypox skin lesions and emergency isolation when necessary is essential. Also, some skin lesions, such as melanoma, can be fatal and must be rapidly distinguished. However, in some cases, it is difficult to distinguish the lesions visually. Methods such as dermoscopy, high-resolution ultrasound imaging, etc. can be used for better observation. But these methods are often based on qualitative analysis, subjective and time-consuming. Therefore, in this study, a quantitative and objective classification tool has been developed to assist dermatologists and scientists. The proposed system classifies seven skin lesions, including monkeypox. A popular approach Vision Transformer and some popular deep learning convolutional networks have been trained with the transfer learning approach and all results have been compared. Then, the models that show the best accuracy score have been combined to make the final prediction using bagging-ensemble learning. The proposed ensemble-based system produced 81.91% Accuracy, 65.94% Jaccard, 87.16% Precision, 74.12% Recall, and 78.16% Fscore values. In terms of different criteria metrics, the system produced competitive or even better results than the literature.

Pixel-level classification of pigmented skin cancer lesions using multispectral autofluorescence lifetime dermoscopy imaging

There is no clinical tool available to primary care physicians or dermatologists that could provide objective identification of suspicious skin cancer lesions. Multispectral autofluorescence lifetime imaging (maFLIM) dermoscopy enables label-free biochemical and metabolic imaging of skin lesions. This study investigated the use of pixel-level maFLIM dermoscopy features for objective discrimination of malignant from visually similar benign pigmented skin lesions. Clinical maFLIM dermoscopy images were acquired from 60 pigmented skin lesions before undergoing a biopsy examination. Random forest and deep neural networks classification models were explored, as they do not require explicit feature selection. Feature pools with either spectral intensity or bi-exponential maFLIM features, and a combined feature pool, were independently evaluated with each classification model. A rigorous cross-validation strategy tailored for small-size datasets was adopted to estimate classification performance. Time-resolved bi-exponential autofluorescence features were found to be critical for accurate detection of malignant pigmented skin lesions. The deep neural network model produced the best lesion-level classification, with sensitivity and specificity of 76.84%±12.49% and 78.29%±5.50%, respectively, while the random forest classifier produced sensitivity and specificity of 74.73%±14.66% and 76.83%±9.58%, respectively. Results from this study indicate that machine-learning driven maFLIM dermoscopy has the potential to assist doctors with identifying patients in real need of biopsy examination, thus facilitating early detection while reducing the rate of unnecessary biopsies.

Optimized Skin Lesion Segmentation: Analysing DeepLabV3+ and ASSP Against Generative AI-Based Deep Learning Approach

Optimized Skin Lesion Segmentation: Analysing DeepLabV3+ and ASSP Against Generative AI-Based Deep Learning Approach

Cutaneous larva migrans: is dermoscopy useful for the treatment?

Cutaneous larva migrans (CLM) is a zoonotic disease endemic in tropical regions. CLM diagnosis mainly relies on the morphology of the skin lesions, however dermoscopy can improve diagnostic accuracy. In this paper, we report two cases of CLM to highlight the importance of dermoscopic follow-up in early identification of treatment failure, as well as the effectiveness of topical ivermectin as a combined medication.

Targeting IL-1 controls refractory pityriasis rubra pilaris.

Pityriasis rubra pilaris (PRP) is a rare inflammatory skin disease with a poorly understood pathogenesis. Through a molecularly driven precision medicine approach and an extensive mechanistic pathway analysis in PRP skin samples, compared to psoriasis, atopic dermatitis, healed PRP, and healthy controls, we identified IL-1β as a key mediator, orchestrating an NF-κB-mediated IL-1β-CCL20 axis, including activation of CARD14 and NOD2. Treatment of three patients with the IL-1 antagonists anakinra and canakinumab resulted in rapid clinical improvement and reversal of the PRP-associated molecular signature with a 50% improvement in skin lesions after 2 to 3 weeks. This transcriptional signature was consistent with in vitro stimulation of keratinocytes with IL-1β. With the central role of IL-1β underscoring its potential as a therapeutic target, our findings propose a redefinition of PRP as an autoinflammatory keratinization disorder. Further clinical trials are needed to validate the efficacy of IL-1β antagonists in PRP.

FGFR2 and NOTCH1 Expression Inversely Correlated in Progressive Cutaneous Carcinogenesis in an Experimental Mouse Model

Cutaneous squamous cell carcinoma (cSCC) is a common and increasingly prevalent form of skin cancer, posing significant health challenges. Understanding the molecular mechanisms involved in cSCC progression is crucial for developing effective treatments. The primary aim of this research was to evaluate the activation of NOTCH1 and FGFR2 oncogenes in inducing skin cancer in FVB/N mice through a stepwise chemical process. Forty female FVB/N mice, aged four weeks, were randomly divided into a control group (n = 8) and two experimental groups (group A: n = 16, group B: n = 16). This study involved subjecting the groups to a two-stage carcinogenesis procedure. This included an initial application of 97.4 nmol DMBA on shaved skin on their backs, followed by applications of 32.4 nmol TPA after thirteen weeks for group A and after twenty weeks for group B. The control group did not receive any treatment. Their skin conditions were monitored weekly to detect tumor development. After the experiment, the animals were euthanized for further tissue sampling. The examination of skin lesions in the experimental groups showed a correlation with tumor progression, ranging from dysplasia to carcinoma. Tumor samples were assessed both histologically and immunohistochemically. Notably, FGFR2 expression was higher in benign, precancerous, and malignant tumors compared to normal tissue. NOTCH1 expression was only elevated in benign tumors compared to normal tissue. This study demonstrates a clear correlation of FGFR2 expression and the progression of cutaneous neoplasms, while NOTCH 1 expression is inversely correlated in FVB/N mice. This suggests an early involvement of these oncogenes in the development of skin tumors.

SSG2: A new modeling paradigm for semantic segmentation

State-of-the-art models in semantic segmentation primarily operate on single, static images, generating corresponding segmentation masks. This one-shot approach leaves little room for error correction, as the models lack the capability to integrate multiple observations for enhanced accuracy. Inspired by work on semantic change detection, we address this limitation by introducing a methodology that leverages a sequence of observables generated for each static input image. By adding this “temporal” dimension, we exploit strong signal correlations between successive observations in the sequence to reduce error rates. Our framework, dubbed SSG2 (Semantic Segmentation Generation 2), employs a dual-encoder, single-decoder base network augmented with a sequence model. The base model learns to predict the set intersection, union, and difference of labels from dual-input images. Given a fixed target input image and a set of support images, the sequence model builds the predicted mask of the target by synthesizing the partial views from each sequence step and filtering out noise. We evaluate SSG2 across four diverse datasets: UrbanMonitor, featuring orthoimage tiles from Darwin, Australia with four spectral bands at 0.2 m spatial resolution and a surface model; ISPRS Potsdam, which includes true orthophoto images with multiple spectral bands and a 5 cm ground sampling distance; ISPRS Vahingen, which also includes true orthophoto images and a 9 cm ground sampling distance; and ISIC2018, a medical dataset focused on skin lesion segmentation, particularly melanoma. The SSG2 model demonstrates rapid convergence within the first few tens of epochs and significantly outperforms UNet-like baseline models with the same number of gradient updates. However, the addition of the temporal dimension results in an increased memory footprint. While this could be a limitation, it is offset by the advent of higher-memory GPUs and coding optimizations. Our code is available at https://github.com/feevos/ssg2.

Hair Shaft Abnormalities as a Dermoscopic Feature of Mycosis Fungoides: Pilot Results.

Diagnosis of persistent erythematous, scaly patches, or plaques can be complex since psoriasis (Ps), eczematous dermatitis (ED), and mycosis fungoides (MF) can be considered. Dermoscopy, which is a noninvasive diagnostic tool, is commonly used to examine blood vessels, scales, and background color; however, research on hair shaft evaluation in inflammatory dermatoses remains scarce. The aim of the study was dermoscopic evaluation of hair shafts in skin lesions localizedon thenon-scalp skin areas in patients diagnosed with MF, Ps, and ED. This was a retrospective evaluation of 55 patients diagnosed with MF, Ps, and ED. Photographic anddermoscopic documentation of these patients and detailed medical history were evaluated. A total of 21 patients with MF, 21 patients with Ps, and 13 patients with ED were evaluated. The examination revealed the presence of various abnormalities of hair shafts (e.g., numerouspili torti, singlepili torti, 8-shaped hairs, pigtail hairs, broken hairs, hair shafts rapidly tapered over long sections, hair shafts irregular in thickness, angulated hairs, branched hairs,the presence of trichorrhexis nodosa,and monilethrix-like hairs), yellow dots, and black dots. The presence ofpili tortiwas found in 80% of patients with MF, compared with 16% of patients with Ps and 8% of patients with ED (p < 0.005), with multiplepili tortifound only in MF patients (67%) (p < 0.005). Statistically significant differences also applied to hair shafts rapidly tapering over long sections and 8-shaped hairs, which occurred only in MF patients (p < 0.005 and p = 0.035, respectively). The presence of hair shaft abnormalities such as numerous pili torti, 8-shaped hairs, and hair shafts rapidly tapering over long sections is an important criterion that should be considered in the dermoscopic differentiation of the patchy/plaque mycosis fungoides and inflammatory dermatoses, such as psoriasis and eczematous dermatitis localizedon thenon-scalp skin areas.

A case report and literature review: Mycobacterium leprae infection diagnosed by metagenomic next-generation sequencing of cerebrospinal fluid

BackgroundLeprosy is a chronic infectious disease caused by Mycobacterium leprae (M. leprae) that is responsible for deformities and irreversible peripheral nerve damage and has a broad spectrum of clinical and serological manifestations. Leprosy primarily affects the peripheral nerves and rarely presents with central nervous system involvement. Diagnosing leprosy can still be difficult in some cases, especially when the infection involves uncommon clinical manifestations and extracutaneous sites. Delayed diagnosis and treatment of leprosy may lead to irreversible damage and death.Case PresentationWe report a case of a 30-year-old female presenting with “repeated high fever with symptoms of headache for 14 days”. On the day of admission, physical signs of lost eyebrows and scattered red induration patches all over her body were observed. The patient’s diagnosis was based on the clinical characteristics using a combination of metagenomic next-generation sequencing (mNGS) of cerebrospinal fluid (CSF) and slit-skin smear. After confirming Listeria meningitis and multibacillary leprosy with erythema nodosum leprosum (ENL), a type 2 reaction, she was treated with ampicillin sodium, dapsone, rifampicin, clofazimine, methylprednisolone, and thalidomide. At the 1-year follow-up, the frequency and severity of headaches have significantly decreased and a good clinical response with improved skin lesions was found.ConclusionThis case highlights the importance of considering leprosy, which is a rare and underrecognized disease, in the differential diagnosis of skin rashes with rheumatic manifestations, even in areas where the disease is not endemic, and physicians should be alerted about the possibility of central nervous system infections. In addition, mNGS can be used as a complementary diagnostic tool to traditional diagnostic methods to enhance the diagnostic accuracy of leprosy.

Exploring the role of vitamin D-VDR pathway in pemphigus foliaceous: a novel perspective on disease pathogenesis.

Several auto-immune diseases have been linked to vitamin D deficiency as a contributing environmental factor. Its pleiotropic effects on the immune system, especially its essential role in maintaining immune tolerance, make the vitamin D pathway of great interest. In this study, we focused on Pemphigus foliaceous (PF) in Tunisian population. we aimed to quantify the Serum 25[OH]D levels using chemiluminescence assay and to analyze the differential expression of the VDR, CYP27B1 and CYP24A1 genes in the circulating blood cells and lesional skin tissue of PF patients using Q-PCR. A genetic explanation was then sought to explore any direct relationship between tag polymorphisms and the inherited features of PF. Results confirmed a vitamin D hypovitaminosis in Tunisian PF patients. Interestingly, a differential gene expression correlated to the disease stratification was noted. Indeed, at the systemic level, an upregulation of VDR and CYP27B1 genes was observed in healthy controls compared to PF patients. Notably, in lesional skin tissue, the clinical and serological remission phase was correlated with high transcriptional levels of the VDR gene and conversely a drop in expression of the CYP24A1 gene. Genetic analysis indicated the involvement of the most appealing polymorphisms, rs2228570 and poly (A) microsatellite, in PF etiopathogenesis. Indeed, CAC13 haplotype was associated with a higher risk of PF development. Our findings suggest that alterations in the vitamin D-VDR pathway may influence PF physiopathology, making this pathway a potential target for pharmacological modulation, especially for cortico-resistant PF patients.

Spectrum of cutaneous lesions in a cohort of patients with neurofibromatosis type 2.

Neurofibromatosis type 2 (NF2) is a rare autosomal dominant syndrome with a predisposition to the development of central nervous system tumors, ophthalmic manifestations, and dermatological lesions. The latter are present in 70-95% of patients and can precede the evolution of other tumors. However, they are not included in the diagnostic criteria and are frequently undervalued during follow-up. An observational cross-sectional study characterizing cutaneous lesions in a cohort of NF2 patients was carried out. Dermatological examinations were performed, and lesions were classified into neural cutaneous tumors (superficial, SNCT, and deep, DNCT), hyperpigmented patches (HyperP), and hypopigmented patches (HypoP). The Dermatology Life Quality Index (DLQI) and EQ-5D questionnaires were applied to evaluate the impact on quality of life. Nineteen patients with a mean age of 36 years were included. Sixteen (84%) patients had cutaneous lesions, mostly developed 10 or more years before the diagnosis. SNCT, DNCT, and HyperP showed similar frequencies (58%). HypoP were observed in only one patient. HyperP developed, on average, earlier than NCT (9.6 vs. 16.5 SNCT, 17.0 DNCT; years). The excised lesions had different histological patterns, including neurofibromas, schwannomas, and a hybrid tumor. Most patients reported a low impact of cutaneous manifestations on the quality of life (DLQI 0 or 1). Cutaneous lesions are frequent in NF2 and may precede the diagnosis by several years. Their identification is important to establish the diagnosis earlier and potentially reduce morbidity and mortality.

Shar-Pei autoinflammatory disease with skin necrosis due to neutrophilic vasculitis: a case report.

A 4-month-old female Shar-pei dog was admitted with apathy, anorexia, and vomiting. The patient had an appropriate vaccination protocol, with the last vaccine administered 2.5 weeks prior to the onset of clinical signs. Physical examination revealed tachycardia, fever and swelling of the tibiotarsal joints. Several diagnostic tests including complete blood cell count, biochemistry profile, urinalysis, thoracic radiographs, hind limbs radiographs, abdominal ultrasound, and infectious diseases tests, were conducted to determine the underlying cause. Shar-Pei Auto-inflammatory Disease (SPAID) was diagnosed. Additionally, the patient developed skin necrosis in the inner aspect of the tibiotarsal joints as a complication. A skin biopsy revealed cutaneous vasculopathy causing degeneration, abrupt ulceration, and ischemic necrosis with intense neutrophilic inflammation of the dermis and subcutis. Moreover, a hospital-acquired infection was identified by skin culture. Debridement of the necrotic skin was performed, and due to its' severity and extent, the wound was closed by secondary intention. A diagnostic protocol and the therapeutic dose of acetylsalicylic acid, which led to clinical improvement, are recommended here. The patient has continued to present episodic manifestations of SPAID mainly fever and swelling of the tibiotarsal joints, but there has been no recurrence of necrosis or other cutaneous lesion in the last two years.

ELA-Net: An Efficient Lightweight Attention Network for Skin Lesion Segmentation

In clinical conditions limited by equipment, attaining lightweight skin lesion segmentation is pivotal as it facilitates the integration of the model into diverse medical devices, thereby enhancing operational efficiency. However, the lightweight design of the model may face accuracy degradation, especially when dealing with complex images such as skin lesion images with irregular regions, blurred boundaries, and oversized boundaries. To address these challenges, we propose an efficient lightweight attention network (ELANet) for the skin lesion segmentation task. In ELANet, two different attention mechanisms of the bilateral residual module (BRM) can achieve complementary information, which enhances the sensitivity to features in spatial and channel dimensions, respectively, and then multiple BRMs are stacked for efficient feature extraction of the input information. In addition, the network acquires global information and improves segmentation accuracy by putting feature maps of different scales through multi-scale attention fusion (MAF) operations. Finally, we evaluate the performance of ELANet on three publicly available datasets, ISIC2016, ISIC2017, and ISIC2018, and the experimental results show that our algorithm can achieve 89.87%, 81.85%, and 82.87% of the mIoU on the three datasets with a parametric of 0.459 M, which is an excellent balance between accuracy and lightness and is superior to many existing segmentation methods.

Reflectance confocal microscopy for plaque psoriasis therapeutic follow-up during an anti-interleukin-17A monoclonal antibody: an observational study

Interleukin-17A therapeutic inhibitors are among the most effective treatment methods for moderate-to-severe plaque psoriasis (PP). Reflectance confocal microscopy is a non-invasive imaging technique already documented to be beneficial in evaluating the follow-up of PP under treatment with topical actives and phototherapy. This study aimed to assess the epidermal and dermal changes associated with psoriasis and its treatment with RCM during systemic secukinumab treatment in patients with moderate-to-severe PP. A pilot study was conducted to evaluate RCM as a non-invasive tool for monitoring secukinumab treatment in patients with PP. For patients receiving secukinumab treatment, lesional skin was selected for RCM imaging, which were recorded at all scheduled times. The RCM evaluation criteria were established based on the histopathological diagnostic criteria for psoriasis. The clinical severity of psoriasis was assessed utilizing the psoriasis area severity index. A total of 23 patients with PP were included in the study. Each patient received 300 mg of subcutaneous secukinumab as induction therapy at baseline and weeks 1–4, followed by maintenance therapy every four weeks. Microscopic confocal changes were observed during the treatment. The results identified early microscopic evidence of the anti-inflammatory activity of secukinumab, which was not detected during the clinical examination. RCM findings correlating with the PASI were used to observe the patient’s response to treatment and were identified as follows: acanthosis and parakeratosis, presence of epidermal and dermal inflammatory cells, presence of non-edge dermal papillae, and vascularization in the papillary dermis. This study is the first to demonstrate the use of RCM as an effective tool for non-invasive monitoring of secukinumab therapeutic response at a cellular level in a clinical or research setting. Early detection of RCM parameters associated with secukinumab activity may facilitate the identification of an early treatment response. RCM appears to be capable of providing practical and helpful information regarding follow-up in patients with PP undergoing secukinumab treatment. RCM may also provide novel perspectives on the subclinical evaluation of PP’s response to biological therapy.

A new nomogram based on ultrasound and clinical features for distinguishing epididymal tuberculosis and nontuberculous epididymitis

Using ultrasound findings and clinical characteristics, we constructed and validated a new nomogram for distinguishing epididymal tuberculosis from nontuberculous epididymitis, both of which share similar symptoms. We retrospectively examined data of patients with epididymal tuberculosis and nontuberculous epididymitis hospitalized between January 1, 2013, and March 31, 2023. Eligible patients were randomly assigned to derivation and validation cohorts (ratio, 7:3). We drew a nomogram to construct a diagnostic model through multivariate logistic regression and visualize the model. We used concordance index, calibration plots, and decision curve analysis to assess the discrimination, calibration, and clinical usefulness of the nomogram, respectively. In this study, 136 participants had epididymal tuberculosis and 79 had nontuberculous epididymitis. Five variables—C-reactive protein level, elevated scrotal skin temperature, nodular lesion, chronic infection, and scrotal skin ulceration—were significant and used to construct the nomogram. Concordance indices of the derivation and validation cohorts were 0.95 and 0.96, respectively (95% confidence intervals, 0.91–0.98 and 0.92–1.00, respectively). Decision curve analysis of this nomogram revealed that it helped differentiate epididymal tuberculosis from nontuberculous epididymitis. This nomogram may help clinicians distinguish between epididymal tuberculosis and nontuberculous epididymitis, thereby increasing diagnosis accuracy.

Enfermedad crónica transmisible y no transmisible, y enfermedad cutánea del paciente migrante

The care of migrant patients includes initial screening and lifelong monitoring, highlighting the importance of preventing and tracking chronic, communicable and non-communicable diseases.The prevalence of hypertension, diabetes mellitus, dyslipidemia, and obesity varies by ethnicity, influenced by genetic factors, lifestyle, and socio-economic status. Preventive measures, health promotion, and risk factor identification are crucial.Chronic communicable diseases may manifest years after transmission, underscoring the necessity of primary care screening, especially for populations from endemic or high-risk areas.Imported skin lesions are a common reason for consultation among migrant and traveller patients. Their ethiology is varied, ranging from common conditions such as scabies, mycoses, and urticaria to tropical dermatoses like filariasis and leprosy.

Dermoscopy Education for Plastic Surgery Residents: How a Brief Theoretical Course and Practical Training Have an Impact.

Currently, the evaluation of pigmented skin lesions relies on dermoscopy, which has become the standard of care. As melanoma is one of the principal areas of expertise in plastic surgery, it is essential that diagnostic skills be acquired during the course of specialization. This study aimed to assess the impact and effectiveness of a brief and intensive dermoscopy training program for plastic surgery residents. This study was carried out on a group of 41 doctors, who were divided into three categories based on their experience in dermoscopy (none, intermediate, and advanced). A preliminary assessment of each participant's baseline knowledge was conducted by using a 15-query test. Subsequently, the participants attended a 90-minute lecture on diagnostic techniques and the process of differentiating between various skin lesions. To determine the effectiveness of the lecture in improving diagnostic skills, the participants were tested immediately after the lecture and again after a 3-month period. At the conclusion of the final examination, all three groups achieved an accuracy rate of at least 80% for dermatoscopic diagnosis. However, none of the groups was completely successful. The variations in diagnostic accuracy among the three groups are presented, and P values were calculated for each group. The short, intensive course of dermoscopy has proven to have a significant positive impact on plastic surgeons in their postdegree training program.

Therapeutic Potential of Mangosteen Pericarp Extract-Loaded Liposomes against Superficial Skin Infection Caused by Staphylococcus pseudintermedius in a Murine Model

α-mangostin (α-MG) demonstrates antibacterial activity against Staphylococcus species. Therefore, this study aimed to explore the antibacterial activity of α-MG-rich mangosteen pericarp extract (MPE)-loaded liposomes against Staphylococcus isolates from companion animal skin diseases in vitro and evaluated their therapeutic potential in a murine model of superficial skin infection caused by S. pseudintermedius. α-MG-rich extract was purified from mangosteen pericarp and then complexed with γ-cyclodextrin (γ-CD), forming the inclusion complexes. Nanoliposomes containing MPE and γ-CD complexes were prepared by adding lecithin and casein. Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of MPE-loaded liposomes were determined using agar dilution and broth microdilution methods. The therapeutic potential of MPE-loaded liposomes was evaluated in vivo on tape-stripped skin lesions infected with S. pseudintermedius. Purified MPE and MPE-loaded liposomes contained 402.43 mg/g and 18.18 mg/g α-MG, respectively. MPE-loaded liposomes showed antibacterial activity against clinical Staphylococcus isolates in vitro but did not show antibacterial activity against Gram-negative bacterial isolates. MPE-loaded liposomes demonstrated consistent MICs and MBCs against Staphylococcus isolates. These liposomes significantly reduced bacterial numbers and lesional sizes in a superficial skin infection model. Moreover, they reconstructed the epidermal barrier in skin lesions. The therapeutic concentrations of MPE-loaded liposomes did not induce cytotoxicity in canine progenitor epidermal keratinocyte cells. In conclusion, MPE-loaded liposomes hold promise for the development of a prospective topical formulation to treat superficial pyoderma in companion animals.

Eosinophils in hidradenitis suppurativa patients exhibit pro-inflammatory traits, implicating a potential pathogenic role in the disease.

Hidradenitis suppurativa (HS) is an inflammatory skin disease characterized by painful nodules, abscesses and purulent secretions in intertriginous regions. Intense pruritus frequently accompanies HS lesions, adding further discomfort for patients. While Th17 pathway activation is implicated in HS pathogenesis, disease mechanisms are still not fully understood, and therapeutics are lacking. Previous reports raise a potential role for eosinophils in HS, showing a strong association of eosinophil levels with disease severity. To investigate eosinophils in HS, we recruited patients and matched healthy controls and then performed flow-cytometry studies, eosinophil stimulation assays, and lesional skin staining for eosinophils. We found that HS patients reported similar levels of pain and itch. Compared to matched controls, HS blood exhibited decreased mature eosinophils and increased numbers of immature eosinophils, coupled with a significant increase in dermal eosinophilic infiltrates. Additionally, IL-17RA+ eosinophils were highly and significantly correlated with multiple HS-related clinical scores. In both stimulated and unstimulated conditions, HS eosinophils showed an inflammatory phenotype versus controls, including an increase in costimulatory T- and B-cell markers (e.g. CD5 and CD40) following all stimulations (TNFα/IL-17A/IL-17F). These findings highlight the significance of pruritus in HS and suggest a higher turnover of eosinophils in HS blood, potentially due to the consumption of eosinophils in skin lesions. Our data delineate the features and functions of eosinophils in HS and suggest that eosinophils participate in disease pathogenesis, advancing Th17-related inflammation. Further studies are needed to investigate eosinophils' response to current HS treatments and their potential as a therapeutic target in the disease.