Introduction: This second part of the S2k guidelines is an update of the 2015 S1 European guidelines.Objective: These guidelines aim to provide an accepted decision aid for the selection, implementation and assessment of appropriate and sufficient therapy for patients with hidradenitis suppurativa/acne inversa (HS).Methods: The chapters have been selected after a Delphi procedure among the experts/authors. Certain passages have been adopted without changes from the previous version. Potential treatment complications are not included, being beyond the scope of these guidelines.Results: Since the S1 guidelines publication, validation of new therapeutic approaches has almost completely overhauled the knowledge in the field of HS treatment. Inflammatory nodules/abscesses/draining tunnels are the primary lesions, which enable the classification of the disease severity by new validated tools. In relation to the degree of detectable inflammation, HS is classified into the inflammatory and the predominantly non‐inflammatory forms. While the intensity of the inflammatory form can be subdivided by the IHS4 classification in mild, moderate and severe HS and is treated by medication accordingly, the decision on surgical treatment of the predominantly non‐inflammatory form is based on the Hurley stage of the affected localization. The effectiveness of oral tetracyclines as an alternative to the oral combination of clindamycin/rifampicin should be noted. The duration of systemic antibiotic therapy can be shortened by a 5‐day intravenous clindamycin treatment. Adalimumab, secukinumab and bimekizumab subcutaneous administration has been approved by the EMA for the treatment of moderate‐to‐severe HS. Various surgical procedures are available for the predominantly non‐inflammatory form of the disease. The combination of a medical therapy to reduce inflammation with a surgical procedure to remove irreversible tissue damage is currently considered a holistic therapeutic approach.Conclusions: Suitable therapeutic options while considering HS severity in the therapeutic algorithm according to standardized criteria are aimed at ensuring a proper therapy.

Background: Continual analyses of patch test results with the European baseline series (EBS) serve both contact allergy surveillance and auditing the value of included allergens.Objectives: To present results of current EBS patch testing, obtained in 53 departments in 13 European countries during 2019 and 2020.Methods: Anonymised or pseudonymised individual data and partly aggregated data on demographic/clinical characteristics and patch test rest results with the EBS were prospectively collected and centrally pooled and analysed.Results: In 2019 and 2020, 22 581 patients were patch tested with the EBS. Sensitization to nickel remained most common (19.8 [19.2–20.4]% positivity [95% confidence interval]). Fragrance mix I and Myroxylon pereirae yielded very similar results with 6.80 (6.43–7.19)% and 6.62 (6.25–7.00)% positivity, respectively. Formaldehyde at 2% aq. yielded almost one percentage point more positive reactions than 1% concentration (2.49 [2.16–2.85]% vs. 1.59 [1.33–1.88]); methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) and MI alone up to around 5% positives. Among the new additions, propolis was most commonly positive (3.48 [3.16–3.82]%), followed by 2‐hydroxyethyl methacrylate (2.32 [2.0–2.68]%).Conclusion: Ongoing surveillance on the prevalence of contact sensitization contributes to an up‐to‐date baseline series containing the most frequent and/or relevant contact sensitizers for routine patch testing in Europe.

Background: Occupational skin diseases have led the occupational disease statistics in Europe for many years. Especially occupational allergic contact dermatitis is associated with a poor prognosis and low healing rates leading to an enormous burden for the affected individual and for society.Objectives: To present the sensitization frequencies to the most relevant allergens of the European baseline series in patients with occupational contact dermatitis (OCD) and to compare sensitization profiles of different occupations.Methods: The data of 16 022 patients considered having OCD after patch testing within the European Surveillance System on Contact Allergies (ESSCA) network between January 2011 and December 2020 were evaluated. Patients (n = 46 652) in whom an occupational causation was refuted served as comparison group.Results: The highest percentages of OCD were found among patients working in agriculture, fishery and related workers, metal industry, chemical industry, followed by building and construction industry, health care, food and service industry. Sensitizations to rubber chemicals (thiurams, carbamates, benzothiazoles) and epoxy resins were associated with at least a doubled risk of OCD. After a decline from 2014 onwards, the risks to acquire an occupation‐related sensitization to methyl(chloro)isothiazolinone (MCI/MI) and especially to methylisothiazolinone (MI) seem to increase again. Sensitization rates to formaldehyde were stable, and to methyldibromo glutaronitrile (MDBGN) slightly decreasing over time.Conclusions: Among allergens in the European Baseline Series, occupational relevance is most frequently attributed to rubber accelerators, epoxy resins and preservatives.

Aging leads to a decline in skin function due to intrinsic factors (genetics, hormones) and extrinsic factors (sun exposure, pollutants). Type I collagen plays a vital role in maintaining skin integrity and elasticity. As aging progresses, collagen synthesis diminishes, resulting in weakened skin structure and wrinkle formation. This systematic review explores the role of type I collagen in skin aging by summarizing key clinical findings. A systematic search was conducted using PubMed and ScienceDirect as the primary databases, including studies published between 2014 and 2025 that addressed type I collagen and skin aging. Eleven clinical studies were selected following PRISMA guidelines. The results consistently show the decline of type I collagen as a central contributor to dermal thinning, loss of elasticity, and the appearance of wrinkles and sagging. Clinical trials demonstrate that collagen supplementation, particularly from hydrolyzed fish cartilage and low-molecular-weight peptides, enhances collagen production, improves skin hydration and texture, and reduces signs of photoaging. Overall, the evidence emphasizes the critical role of type I collagen in skin aging and suggests that targeted collagen supplementation may serve as an effective strategy to maintain skin structure and combat visible signs of aging.

Chronic wounds can severely limit patient's social life. This cross‐sectional study investigated quantitatively social support of patients with chronic wounds, its association with health‐related quality of life as well as qualitatively changes in social participation of these patients. Overall, 263 patients from seven countries participated. The most frequent wound class was leg ulcer (49.2%). Results revealed generally high levels of social support (mean global score: 5.5) as measured with the Multidimensional Scale of Perceived Social Support. However, individuals differed considerably (range 1.0–7.0). All dimensions of social support differed by patients' family and living situations (p < 0.001 to p = 0.040) and were positively correlated with generic health‐related quality of life (r = 0.136–0.172). Having children, living with others and being in a relationship were significant predictors of having higher global social support. Patients reported great support from family members. Many participants reported no changes in relationships with friends. Wound care managers took an important role and provided additional emotional support. Patients reported a range of discontinued activities. Despite the high overall level of social support, inter‐individual differences should be acknowledged. The importance of family carers should be acknowledged to be able to reduce caregiver burden and to ensure high‐qualitative wound care.

Atopic diseases, including atopic dermatitis (AD) and allergic asthma (AA), are characterized by complex immune responses involving various T cells subsets and their cytokine profiles. It is assumed that single nucleotide polymorphisms (SNPs) in the Vitamin D receptor (VDR) gene and the Vitamin D-binding protein (GC) gene are related to the action of Vitamin D and, consequently, play a role in regulating the immune response. However, there is not enough data to unequivocally support the hypothesis about the relationship between T cells profile and VDR or GC SNPs. Two hundred sixty-six subjects (aged > 18 years) were involved in the study: 100 patients with mild or moderate AD, 85 patients with mild or moderate AA, and 81 healthy individuals. Blood cell counts were determined by standard methods. Flow cytometric analysis was used to evaluate CD4⁺ T-helper (Th) cell subtypes: Th2, Th1, Th17, and T regulatory (Treg) cells in peripheral blood. Measurements of cytokines, total immunoglobulin E (IgE), and Vitamin D levels in serum were evaluated by ELISA. Significantly higher levels of Th1, Th2, and Th17 cells, along with lower levels of Tregs, were found in patients with atopic diseases compared to healthy individuals. Additionally, higher serum levels of interleukin (IL) 5, IL-17A, and transforming growth factor-β1 (TGF-β1), as well as lower levels of IL-10, were observed in patients with atopic diseases than in control. The study established associations between VDR SNPs and immune profiles: the AA genotype of rs731236 was associated with increased Th2 and Th17 cells and a higher Th1/Th2 ratio; the GG genotype of rs731236 was linked to decreased serum IL-10 and TGF-β1 levels; and the TT genotype of rs11168293 was associated with increased IL-10 levels. Additionally, the GG genotype of GC gene SNP rs4588 was associated with reduced Th2 and Th17 lymphocytes, while the TT genotype of rs4588 was linked to decreased IL-10 levels. Furthermore, the CC genotype of rs7041 was associated with higher levels of Th2, Th17, IL-10, and IL-35, as well as reduced levels of TGF-β1, while the GG genotype of rs3733359 was associated with reduced IL-10 levels. In conclusion, our study demonstrates that the Vitamin D receptor gene single nucleotide polymorphisms rs731236 and rs11168293, along with polymorphisms in the Vitamin D-binding protein gene (rs4588, rs7041, rs3733359), are significantly associated with variations in T cell profiles in atopy. These variations may play a crucial role in promoting inflammation and provide insight into the genetic factors contributing to the pathogenesis of atopy.