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.

Hidradenitis suppurativa (HS), a chronic recurrent inflammatory skin disease of the hair follicle, manifests with deep-seated, painful nodules, abscesses, sinus tract formation, and subsequent scarring, most commonly localized in the axillary, inguinal, and anogenital regions.^1-3 The tissue destruction and scarring has historically led to the belief that HS is also a surgical disease.⁴ Patients are generally treated with surgery owing to extensive sinus tract/fistula/tunnel formation, destruction of anatomic feature and/or function, and eventually contracted painful scars.^3,5 However, postsurgical recurrence may occur in up to 70% of patients, depending on the type of procedure performed and the anatomic surgical site.¹ Wide-excision surgery, the most radical and invasive procedure used for HS, is reported with low recurrence rate for primary and secondary intention healing.^5,6 Although surgical management may be performed for the most severe lesions, patients may have lesions in other anatomical areas and therefore require anti-inflammatory treatment simultaneously with surgical management.^6,7 The European S1 HS guidelines suggest that treatment is based on individual subjective effect and objective severity of disease.¹

Hidradenitis suppurativa (HS) is a chronic inflammatory disease manifesting in inverse body regions. In a systematic review, the role of hormones in HS will be presented to better understand the pathomechanisms of HS. The review is based on the PRISMA criteria. Systematic research was carried out using keywords. Subsequently, the data were analyzed based on the clinical response and other relevant information. The main focus of our systematic review was on HS manifestation, exacerbation, sex hormones, antiandrogen therapy, thyroid function, polycystic ovary syndrome, insulin resistance, and adipokines. In HS, there appears to be a dysregulated adipokine release that is shifted towards pro-inflammatory adipokines. Insulin resistance is significantly more common in HS than in healthy patients regardless of BMI, age, and gender. Insulin resistance in HS patients leads to further cardiovascular disease. The mechanism of insulin resistance and role of adipokines should be investigated in future studies to better provide the pathomechanisms of HS. The role of androgens seems to be important in a certain subgroup of female patients. Anti-androgenic therapy can be useful and helpful in some patients. However, further studies are needed to better understand the hormonal relationship in HS.

Hidradenitis suppurativa (HS) is a chronic skin disease that predominantly affects the skin of the intertriginous area through an inflammatory process and results in recurrent nodules, abscesses, sinuses, fistulas, and scarring.^1,2 Because the precise description of HS may provide a challenge, considerable efforts have been made to formulate diagnostic criteria and validate clinical descriptive terms for the lesions occurring in patients with HS.^3,4 In addition, an international initiative (HS core outcomes set international collaboration) has started to develop a list of mandatory outcomes that should be measured in clinical trials on the treatment of HS.⁵ However, the variation in clinical appearance and the variability in response to a wide range of proposed treatments underline the importance of an accurate disease severity assessment tool.^1,6