Behcet's disease (BD) is a chronic, multisystem autoimmune vasculitis that can cause severe genital ulcers. Giant vulvar ulcers (diameter ≥4 cm) secondary to BD pose significant therapeutic challenges due to their refractory nature, risk of functional impairment, and impact on fertility and aesthetic outcomes.

The article describes a clinical case of Behcet's disease, manifested by recurrent aphthae in the oral cavity and genital ulcers. The disease occurred in childhood in the form of chronic recurrent aphthous stomatitis.

Behçet's disease (BD) is a multi-system inflammatory disorder characterised by recurrent oral, genital or ocular inflammation, and may present with variable-vessel vasculitis.[1] It has a distinctive geographic distribution, with the highest prevalence along the historic Silk Road, particularly in Turkey and Iran.[2- 4] In contrast, BD is considered rare in India, with limited epidemiological data and predominantly hospital-based series.[5, 6] Although recurrent oral ulcers are nearly universal, systemic manifestations, including ocular, vascular, neurological and gastrointestinal involvement, vary across regions.[2, 3] Fever is not a classic presenting symptom in mucocutaneous disease, but may occur in vascular or neuro-Behçet's, where it reflects heightened systemic inflammatory activity.[7] Consequently, BD may masquerade as a prolonged febrile illness, particularly before characteristic features emerge. Atypical presentations may delay diagnosis, particularly in low-prevalence regions.

A 20-year-old woman with a history of recurrent oral ulcers and acneiform rashes presented with fever, severe trismus, genital ulcers, a positive pathergy test, and laboratory evidence of systemic inflammation. Fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) demonstrated increased uptake in the masticatory muscles, corroborated by magnetic resonance imaging showing muscle swelling. These findings led to the diagnosis of masticatory myositis associated with Behçet's disease. Following colchicine therapy, a follow-up 18F-FDG PET/CT revealed decreased FDG uptake, correlating with clinical improvement. This case highlights masticatory myositis as a rare cause of trismus in Behçet's disease, as demonstrated by 18F-FDG PET/CT.

Herpes simplex virus 2 (HSV-2) is a widespread sexually transmitted infection in the human population. Infection by HSV-2 is lifelong and causes periodic genital ulcers, which can lead to increased co-infection of human immunodeficiency virus (HIV). No clinical vaccine is available for HSV-2, and current antivirals used to suppress HSV-2 diseases have limited efficacy. Thus, there is a need to identify new antivirals against HSV-2. Given the lack of new treatment options, we established a cell-based high throughput screening (HTS) platform using an HSV-2 reporter virus and small molecule libraries to identify novel inhibitors of HSV-2. Our HTS achieved with a Z'- factor score of 0.86, which represents high robustness and reproducibility for this screen. We screened over 90,000 compounds, and ∼2500 small compounds were identified as potential inhibitors of HSV-2. From this set, 294 compounds were further analyzed in secondary assays, and we identified 2 potential inhibitors of HSV-2. These results indicate that we have developed a robust HTS to select for compounds that inhibit HSV gene expression in cell culture, which can lead to the discovery novel of inhibitors or host pathways involved in HSV-2 lytic infection.

Behçet's syndrome (BS) is a chronic, multisystem variable vessel vasculitis defined by recurrent oral and genital ulcers, diverse mucocutaneous lesions, and potential involvement of the eyes, joints, vasculature, central nervous system, and gastrointestinal tract. Diagnosis remains a clinical challenge given the absence of pathognomonic laboratory or histological findings. We present a case of a 36-year-old Caucasian male patient with hypothyroidism who developed a severe, rapidly progressive first episode of BS characterized by hemorrhagic vesicular and bullous skin lesions, oral ulceration, and necrotic genital ulceration requiring surgical debridement. Extensive infectious evaluation, including plasma cell-free metagenomic next-generation sequencing (cf-mNGS), was entirely negative. Serologic workup was unremarkable; HLA-B51 was negative, and pathergy was equivocal. Skin punch biopsy demonstrated pan-dermal neutrophilic inflammation with acute vasculitis and focal epidermal necrosis - a critical histopathological feature distinguishing BS from Sweet syndrome, in which true vasculitis is characteristically absent. Under the International Criteria for Behçet's Disease (ICBD), the patient scored ≥4 points (oral ulcers: 2 points; genital ulcers: 2 points; skin lesions: 1 point). He responded to high-dose corticosteroids (prednisone 50 mg daily) and colchicine, achieving full remission within nine weeks with no recurrence. This case illustrates the diagnostic complexity of BS in the absence of classic genetic markers, emphasizes histopathology as the critical discriminator from neutrophilic dermatosis mimics, and underscores the importance of systematic multidisciplinary evaluation before initiating immunosuppressive therapy.

Behçet's disease (BD) in childhood is characterised by recurrent inflammatory flares that can result in significant morbidity, most notably with ocular, mucocutaneous, and musculoskeletal manifestations. Timely detection of impending flares is difficult in routine practice, and digital health technologies coupled with patient-reported symptom diaries have been proposed as a candidate route to real-time disease surveillance. As a first methodological step before any prospective evaluation in real patients, we set out to demonstrate that a diary-based machine learning (ML) pipeline can recover a transparent, rule-based flare definition under fully controlled in silico conditions, and to characterise the behaviour of such a pipeline before any clinical deployment is considered. A synthetic, longitudinally structured BD dataset was generated in silico, comprising 100 virtual pediatric patients each followed daily for 90 days (9000 patient-day observations). No real patient data were collected; the dataset was constructed solely as a methodological proof-of-concept and is not presented as a substitute for prospectively collected clinical observations. All simulation parameters were drawn from published pediatric BD distributions and are fully documented in Supplementary Table S1. Recorded features comprised oral and genital ulcers, mucocutaneous lesions, ocular involvement, joint pain or swelling, fever, fatigue, gastrointestinal and vascular involvement, treatment class, and adherence score. Flare was operationalised by a transparent composite rule: ≥2 of {oral ulcer, genital ulcer, joint pain/swelling, ocular involvement, skin lesion} accompanied by either fever >38°C or severe fatigue (≥3 on a 0-3 ordinal scale). Six ML algorithms were compared: Logistic Regression, Random Forest, XGBoost, LightGBM, Support Vector Machine (RBF kernel), and Multilayer Perceptron. The dataset was split at the patient level (80/20) with stratification by patient-level flare prevalence to prevent within-patient leakage. Model performance was evaluated by 5-fold cross-validation using accuracy, sensitivity, specificity, F1-score, AUC, Matthews correlation coefficient (MCC), Brier score, and decision curve analysis. SHAP analysis and unsupervised k-means clustering were used for interpretability. Three pre-specified robustness analyses were performed: label-noise injection (5% and 10% flips on the training partition only), flare-prevalence shifts (5% and 30%), and AR-1 mis-specification (φ ± 0.20); results appear in Supplementary Table S2. Reporting followed the TRIPOD+AI and GAMER guidelines (Supplementary Checklist). Across all six classifiers, tree-based ensembles recovered the labelling function most efficiently. Random Forest achieved the best overall performance (accuracy 0.86, recall 1.00, AUC 0.85, MCC 0.72, Brier 0.11), closely followed by XGBoost (AUC 0.81, MCC 0.66, F1 0.83) and LightGBM (AUC 0.80, MCC 0.63, F1 0.81). Logistic regression, SVM (RBF), and MLP clustered at AUC 0.75-0.77. SHAP analysis ranked oral ulcers, joint pain, and fever as the strongest predictors, with fatigue and ocular involvement contributing to a lesser degree. Because these features are explicit constituents of the labelling rule, their SHAP rankings index pipeline-recovery rather than independent biological discovery. Unsupervised clustering identified three phenotypic groupings consistent with the simulated symptom distributions, serving as an internal consistency check on the data-generating mechanism rather than a novel clinical finding. Decision curve analysis showed a mathematically well-defined positive net benefit across threshold probabilities from 0.10 to 0.70 under the synthetic data-generating distribution, which we do not interpret as evidence of real-world clinical utility. Robustness analyses confirmed that pipeline performance degraded gracefully under modest label noise and prevalence shift but did not establish clinical generalisability. These in silico results provide a methodological proof-of-concept showing that a diary-based ML pipeline can faithfully recover a transparent, rule-based flare definition in pediatric BD with sensible calibration and interpretable feature attribution. They do not, in themselves, establish that such a pipeline would generalise to real patients, in whom flare adjudication requires clinician evaluation and major-organ surveillance that simple diary-based composites cannot replicate. Prospective multicentre validation against independently adjudicated flare labels and post-hoc probability calibration will be required before any clinical role can be considered.

Chemsex involves the use of psychoactive substances to facilitate or enhance sexual activity, particularly among gay, bisexual, and other men who have sex with men (GBMSM). Common substances used include methamphetamine, gamma-hydroxybutyric acid/gamma-butyrolactone (GHB/GBL), mephedrone, ketamine, inhaled nitrites ('poppers'), and cocaine, all of which are linked to various dermatological complications. Dermatologists are often the first to recognize skin and mucosal manifestations in chemsex users, providing an opportunity for timely intervention and risk reduction. A targeted literature search until January 2026 was conducted using PubMed/MEDLINE to identify relevant publications on chemsex-associated dermatological manifestations. The studies included were observational, case series, case reports and clinical guidelines, focusing on the clinical presentation, substances involved and routes of administration. Cutaneous and mucosal lesions vary depending on the substance and route of administration. Poppers dermatitis, commonly seen in GBMSM, is a well-defined manifestation and often misdiagnosed as impetigo. 3,4-Methylenedioxymethamphetamine (MDMA), often used in chemsex, leads to oral mucositis and painful aphthous-like ulcers due to its acute effects, such as bruxism and xerostomia. Injection-related lesions from substances like mephedrone and ketamine are particularly concerning, often resembling infectious or vasculitic processes and frequently leading to delayed diagnoses. Cocaine use, especially when combined with levamisole, can cause cutaneous necrosis, vasculitis and soft tissue infections. GHB/GBL use may cause traumatic genital and perianal injuries due to reduced pain sensitivity, while alprostadil injections can result in localized oedema, haematomas or fibrosis. Lastly, constricting devices used in chemsex settings can lead to mechanical trauma, ischaemic injury and chronic complications like fibrosis and penile deformities. Chemsex is a significant public health concern with dermatological implications. Improved awareness of characteristic cutaneous and mucosal lesions can support earlier recognition, targeted investigation and non-stigmatizing risk-reduction advice and referral. More prospective studies and standardized diagnostic criteria are needed to enhance the management of chemsex-related dermatological and systemic complications.