Acrodermatitis continua of Hallopeau is a rare, chronic, relapsing form of localized pustular psoriasis characterized by painful sterile pustules and progressive destruction of the nail apparatus. Its clinical and dermoscopic features may be atypical, leading to diagnostic delays and inappropriate treatment. We present the case of a 78-year-old man with a one-year history of painful hyperkeratotic lesions affecting several fingers, with recent worsening, extension, and purulent discharge. Examination revealed bilateral chronic paronychia with peripheral erosions involving both thumbs and the left index finger, covered by thick yellow-green hyperkeratosis and purulent discharge. Proximal erythematous, crusted plaques extended to the digit bases. Chronic fungal paronychia with secondary bacterial infection was initially suspected. Bacterial and fungal cultures from purulent discharge and erosive areas were negative, although Pseudomonas aeruginosa was isolated from the extracted hyperkeratotic material. Following local care and antimicrobial therapy, the hyperkeratosis cleared, revealing anonychia and a markedly inflamed, erosive periungual surface. Dermoscopy showed large structureless whitish areas corresponding to giant pustules, coalescent milky pustules, yellowish crusts, whitish scales, and regularly distributed dotted, globular, and glomerular vessels. Shiny reticular white structures and small polymorphous white-yellow structures were also observed, mimicking nail erosive lichen planus and candidiasis. Histopathology demonstrated psoriasiform acanthosis, laminated parakeratosis, Munro microabscesses, dilated papillary dermal capillaries, and a neutrophilic and lymphohistiocytic infiltrate without interface changes, confirming acrodermatitis continua of Hallopeau with secondary bacterial superinfection. Acrodermatitis continua of Hallopeau should be considered in the differential diagnosis of chronic, destructive paronychia, particularly when accompanied by nail dystrophy or anonychia. Massive hyperkeratosis and atypical dermoscopic findings may obscure the diagnosis and mimic other inflammatory or infectious disorders. Accurate diagnosis requires integration of clinical, dermoscopic, microbiologic, and histopathologic findings to enable timely and appropriate management.

Background Nail abnormalities are common but often overlooked manifestations of type 2 diabetes mellitus (DM). Their relationship with glycemic control and disease duration remains incompletely understood. This study aimed to evaluate the spectrum of nail abnormalities in patients with type 2 DM and to determine their association with glycemic parameters and duration of DM. Methods A retrospective observational study was conducted among patients with type 2 DM attending a tertiary care hospital between January 2023 and December 2024. Patients were divided into two groups: those with nail abnormalities (Group A) and those without nail abnormalities (Group B). Demographic and clinical data, fasting blood sugar (FBS), postprandial blood sugar (PPBS), random blood sugar (RBS), glycated hemoglobin (HbA1c), and duration of DM were analyzed. Nail abnormalities were evaluated clinically and by onychoscopy. Statistical analysis included the Chi-square test, Student's t-test, correlation analysis, and receiver operating characteristic (ROC) curve analysis. Results The study consisted of 100 patients in each group, with Group A (M: 68, F: 32) and Group B (M;52, F: 48). Longitudinal ridging (64%) was the most frequent nail abnormality, followed by onychomycosis (36%), chronic paronychia (26%), Beau's lines (25%), and nail dystrophy (18%). Patients with nail abnormalities had significantly higher FBS, PPBS, RBS, and HbA1c levels than those without nail abnormalities (all p < 0.001). ROC curve analysis demonstrated that glycemic parameters exhibited superior predictive performance for nail abnormalities compared with the duration of diabetes, with RBS showing the highest sensitivity and HbA1c the highest specificity. Although Beau's lines were associated with longer disease duration, most nail abnormalities did not demonstrate a significant relationship with the duration of diabetes. Total nail change scores showed a positive correlation with worsening glycemic parameters. Conclusions Nail abnormalities in type 2 DM are closely associated with poor glycemic control and may reflect cumulative metabolic injury more closely than the chronological duration of disease. Routine nail examination, supplemented by onychoscopy when indicated, may serve as a simple, non-invasive adjunct for identifying patients who require closer metabolic evaluation. Prospective longitudinal studies are warranted to validate these findings.

Prophylactic administration of systemic antibiotics is widely used to mitigate skin-related adverse events (AEs) during anti-EGFR monoclonal antibody (mAb) therapy for metastatic colorectal cancer (mCRC). However, the optimal duration of prophylaxis remains unclear, and prolonged use may increase risks such as hepatotoxicity and reduced efficacy. In this single-center retrospective study, mCRC patients receiving anti-EGFR mAbs and prophylactic minocycline as part of a standardized outpatient skin care program were analyzed. Patients were classified into 2 groups based on minocycline duration: 8 weeks or >8 weeks. The primary endpoint was the incidence of Grade ≥2 skin-related AEs at weeks 8 and 12. Secondary endpoints included specific AE types, liver dysfunction, and risk factor analysis using multivariate logistic and Cox regression models. Seventy-three patients were included (8-week group: n = 24; >8-week group: n = 49). At week 12, the incidence of Grade ≥2 skin-related AEs was significantly lower in the 8-week group (54.2% vs 81.6%, p = 0.013), particularly for paronychia (16.7% vs 42.9%, p = 0.027). The incidence of liver dysfunction was also lower (16.7% vs 40.8%, p = 0.039). Logistic regression identified younger age and prolonged minocycline use as independent risk factors at week 12, while Cox regression showed age ≥65 years increased risk over the treatment period. Limiting prophylactic minocycline administration to 8 weeks may reduce skin-related AEs and hepatotoxicity. Patient age and treatment duration should be considered when optimizing supportive care protocols for anti-EGFR mAbs therapy.

Acute paronychia in children is typically associated with trauma or habitual behaviors, whereas cosmetic-related cases are rarely reported. We describe a 4-year-old girl who developed acute paronychia with persistent green nail-bed pigmentation following the application of nail polish to a nail with pre-existing cuticular disruption. Staphylococcus epidermidis was isolated from purulent discharge, while Pseudomonas aeruginosa was not detected. The clinical course supports a dual pathogenic mechanism involving bacterial invasion through a compromised cuticle and chemical irritation from cosmetic components. The observed green discoloration, confined to the nail bed and occurring in the absence of P. aeruginosa, represents an atypical presentation distinct from classical chloronychia. This case highlights that cosmetic products may represent an underrecognized trigger of nail infections in children, particularly when applied to compromised nail units, and underscores the need for clinician awareness as the use of children's cosmetic products continues to expand.

Paronychia represents an underexplored clinical condition with limited alternatives to conventional antimicrobial therapies, which are increasingly compromised by antibiotic resistance and toxicity. Here, we report for the first time the extracellular biosynthesis of silver nanoparticles (BAgNPs) using Bacillus stercoris 2AT10, a marine-derived bacterium not previously exploited for nanoparticle production. By integrating green nanotechnology with genome mining approaches, we investigated the molecular basis underlying nanoparticle formation and evaluated the potential of BAgNPs against pathogens associated with paronychia. Physicochemical characterization by ultraviolet-visible (UV-Vis) spectroscopy confirmed the presence of particles, with mean sizes ranging from 47 to 87 nm measured by dynamic light scattering (DLS). Their spherical shape was confirmed by transmission electron microscopy (TEM), whereas Fourier-transform infrared (FTIR) spectroscopy suggested the presence of hydroxyl, amide, and nitrogen-containing groups possibly associated with reducing or capping action. Genes encoding nitrate reductases, laccases, and bioactive secondary metabolites, such as bacillibactin, subtilosin A, bacillaene, bacilysin and fengycin, that may be involved in silver ion reduction and nanoparticle stabilization were identified by genome annotation using eggNOG-mapper and antiSMASH. The biosynthesized AgNPs exhibited potent broad-spectrum antimicrobial activity against paronychia-associated pathogens, notably with inhibition zones of 25.8 mm for Staphylococcus aureus and of 23.2 mm for Pseudomonas aeruginosa. The Hen's Egg Test on the Chorioallantoic Membrane (HET-CAM) assay showed the nonirritating profile of the biosynthesized particles (irritation index ≤ 1), supporting further investigation of their suitability for topical applications, pending additional biocompatibility studies. Collectively, these findings establish B. stercoris-derived BAgNPs as a promising green nanotechnology platform to address the unmet need for safe and effective prophylactic agents against bacteria associated with paronychia, with additional potential as antimicrobial preservatives for dermocosmetic formulations.

Skin toxicities like paronychia and acneiform rash are common side effects of epidermal growth factor receptor tyrosine kinase inhibitors (EGFR TKI) and significantly impact patients' quality of life. Tetracycline antibiotics are the recommended first-line treatment but can cause side effects, leading to intolerance and untreated toxicities, highlighting needs for alternative therapies. We present a case of stage IV EGFR-mutated non-small cell lung cancer (NSCLC) treated with the second-generation EGFR TKI, dacomitinib. The patient developed grade 3 skin toxicities and was subsequently treated with azithromycin after demonstrating intolerance to tetracycline antibiotics. Azithromycin was administered using various dosing strategies, and we found 500 mg every other day might be the most effective regimen for treating EGFR-TKI-induced acneiform rash. However, this approach appeared to be less effective in managing paronychia.

Paronychia is a frequent cutaneous adverse event associated with MEK inhibitor therapy and may significantly impair quality of life and compromise treatment adherence. Treatment is usually medical, with poor and unsustained results. We retrospectively evaluated the safety and efficacy of CO2 laser matrixectomy in children at a tertiary center between 2016 and 2026. Five patients with prolonged symptoms despite multiple conservative treatments were identified. Complete resolution was achieved in all patients, with no procedure-related complications. MEK inhibitor therapy was continued without recurrence of paronychia. Outcomes remained favorable during a mean follow-up of 4 years.