Anoscrotal fistula is a rare variant of anal fistula, often mimicking primary scrotal disease and causing diagnostic delay. Unlike typical cryptoglandular fistulas, anoscrotal extensions are frequently linked to Crohn's disease, tuberculosis, hidradenitis suppurativa, or actinomycosis. Published data remain scarce, especially in Europe. This study aimed to describe the clinical features, etiologies, imaging findings, management, and outcomes of anoscrotal fistulas treated in a French tertiary center. We retrospectively reviewed all men managed for anoscrotal fistula at the Institute of Proctology, Paris Saint-Joseph Hospital, between 2014 and 2024. Demographic, clinical, radiological, surgical, and outcome data were analyzed. Healing was defined as closure of all fistula openings without recurrence at last follow-up. Twenty-nine patients were included (mean age 48.2 years). Initial presentation was abscess in 55% and purulent discharge in 45%. External scrotal openings were present in 90%. Magnetic resonance imaging (MRI) identified complex tracts in 59% of cases. Etiologies were cryptoglandular (63%), Crohn's disease (15%), hidradenitis (11%), tuberculosis (7%), and actinomycosis (4%). Nineteen patients (66%) had prior anorectal surgery. Most (72%) underwent initial seton drainage, followed by fistulotomy (31%), advancement flap (12%), or other sphincter-preserving techniques. A urologist was involved in 31% of cases. After a median follow-up of 22 months, 59% healed, 28% had persistent disease, and none recurred once healed. Continence was preserved, and 73% of patients were highly satisfied. No predictors of healing were identified. This series represents one of the largest European experiences with anoscrotal fistula. Findings emphasize frequent non-cryptoglandular causes, the key role of MRI, and the need for multidisciplinary, individualized management.

This second part of the S2k guidelines is an update of the 2015 S1 European guidelines. 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). 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. 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. Suitable therapeutic options while considering HS severity in the therapeutic algorithm according to standardized criteria are aimed at ensuring a proper therapy.

Hidradenitis suppurativa (HS) is a recurrent inflammatory skin disease that, apart from rare causative loss-of-function mutations, has a widely unknown genetic aetiology. To estimate the relative importance of genetic and environmental factors underlying susceptibility to HS. Via the Danish Twin Registry and the Danish National Patient Registry we pulled together information on zygosity with that of HS status. Cases of HS were identified by the International Classification of Diseases (ICD)-8 (705·91) and ICD-10 (L73·2). Heritability was assessed by the classic biometric model and the possibility of gene-gene interaction via the multilocus modelling approach. Among 100 044 registered twins, we found 170 twins (from 163 pairs) diagnosed with HS. The seven concordant pairs were all monozygotic. Monozygotic twins had a case-wise concordance rate of 28% [95% confidence interval (CI) 7-49], corresponding to a familial risk of 73 (95% CI 13-133) times that of the background population. The biometrical modelling suggested a heritability of 0·80 (95% CI 0·67-0·93), and the multilocus index estimate was 230 (95% CI 60-400). This is highly indicative of gene-gene interactions, with the possibility of up to six interacting loci. This twin study was substantially larger and employed a more valid phenotype than previous studies. Genetics account for the majority of HS susceptibility, and HS is most likely caused by gene-gene interactions rather than monogenetic mutations or solely additive genetic factors. New approaches aimed at assessing potential interactions at a single-nucleotide polymorphism (SNP)-SNP level should be implemented in future HS genome-wide association studies.

Hidradenitis suppurativa is a chronic, inflammatory skin disease in which genetic factors are considered to play a role, with up to 38% of patients reporting a family history. Variations in the γ-secretase genes are found mainly in familial cases with an autosomal dominant pattern of inheritance. These variations are rare in the general population with hidradenitis suppurativa, even in patients who report a family history of the disease. To assess the heritability of hidradenitis suppurativa in a nationwide Dutch twin cohort. In this cross-sectional study on self-reported hidradenitis suppurativa conducted from 2011 to 2016, data were collected from twins participating in the surveys of the nationwide Netherlands Twin Register. All complete twin pairs answering the question on hidradenitis suppurativa in the survey were included: 978 female monozygotic twin pairs and 344 male monozygotic twin pairs and 426 female dizygotic twin pairs, 167 male dizygotic twin pairs, and 428 dizygotic twin pairs of the opposite sex. Statistical analysis was performed from July to November 2019. The main outcome is the proportion of susceptibility to hidradenitis suppurativa due to additive genetic factors (narrow-sense heritability), dominant genetic factors, common or shared environmental factors, or unshared or unique environmental factors. The main outcome was evaluated prior to data collection. The prevalence of hidradenitis suppurativa among twin pairs was 1.2% (58 of 4686); the mean (SD) age was 32.7 (15.4) years. The narrow-sense heritability of hidradenitis suppurativa was 77% (95% CI, 54%-90%), with the remainder of the variance due to unshared or unique environmental factors based on an age-adjusted model combining additive genetic factors and unshared or unique environmental factors. The high heritability found in this study suggests a stronger than previously assumed genetic basis of hidradenitis suppurativa. Environmental factors were also shown to contribute to the susceptibility to hidradenitis suppurativa, supporting a multifactorial cause of the disease. Moreover, the results of this study strongly support the need for a global genome-wide association study in the general population of patients with hidradenitis suppurativa.

Clinical data on hidradenitis suppurativa (HS) derived mainly from studies in Western Europe and the USA, raising the risk of potential selection bias. According to the official data, during 2006-2015 the incidence of HS in Lithuania was 23.5 cases per 100,000 population with a female-to-male ratio of 2:1. A more fine-grained data set would however be of great relevance to further understanding this disease. Collection of standardized data enables the comparison of populations of patients across samples. To present a cohort of HS patients with uniformly collected data according to European Hidradenitis Suppurativa Foundation/European Reference Network-Skin recommendations. The demographic and clinical data of a total of 37 HS patients, included over a 3-year period (from 2016 to January 2019) in a local database of the reference centre of Rare Skin Diseases in the Hospital of the Lithuanian University of Health Sciences Kauno Klinikos, were analysed. Non-parametric tests such as χ2 and Mann-Whitney were used for assessing interdependence between qualitative data. Logistic regression analysis was performed to find out the factors statistically related with significant diagnostic delay. The mean duration of diagnosis delay was 5.5 (±5.9) years in females and 6.6 (±8.2) years in males. A significant delay (>2 years) was reported in 29/37 (78.4%) cases and was not related with sex, age at HS diagnosis or disease severity. The groin area was more affected in females than in males. There was no statistically significant difference between sex and Hurley stage, HS Physician Global Assessment, International Hidradenitis Suppurativa Severity Score System, visual analogue scale and Dermatology Life Quality Index scores. Combined (medical and surgery) HS treatment was applied to 46.0% and monotherapy (medical or surgery) to 54.0% of patients. Standardized collection of epidemiological and clinical data is required to improve the quality of HS patient data and allow for international comparisons and pooling of data for research purposes.