Immunology of psoriasis.

The skin is the front line of defense against insult and injury and contains many epidermal and immune elements that comprise the skin-associated lymphoid tissue (SALT). The reaction of these components to injury allows an effective cutaneous response to restore homeostasis. Psoriasis vulgaris is the best-understood and most accessible human disease that is mediated by T cells and dendritic cells. Inflammatory myeloid dendritic cells release IL-23 and IL-12 to activate IL-17-producing T cells, Th1 cells, and Th22 cells to produce abundant psoriatic cytokines IL-17, IFN-γ, TNF, and IL-22. These cytokines mediate effects on keratinocytes to amplify psoriatic inflammation. Therapeutic studies with anticytokine antibodies have shown the importance of the key cytokines IL-23, TNF, and IL-17 in this process. We discuss the genetic background of psoriasis and its relationship to immune function, specifically genetic mutations, key PSORS loci, single nucleotide polymorphisms, and the skin transcriptome. The association between comorbidities and psoriasis is reviewed by correlating the skin transcriptome and serum proteins. Psoriasis-related cytokine-response pathways are considered in the context of the transcriptome of different mouse models. This approach offers a model for other inflammatory skin and autoimmune diseases.

IFNγ-Dependent Tissue-Immune Homeostasis Is Co-opted in the Tumor Microenvironment.

Homeostatic programs balance immune protection and self-tolerance. Such mechanisms likely impact autoimmunity and tumor formation, respectively. How homeostasis is maintained and impacts tumor surveillance is unknown. Here, we find that different immune mononuclear phagocytes share a conserved steady-state program during differentiation and entry into healthy tissue. IFNγ is necessary and sufficient to induce this program, revealing a key instructive role. Remarkably, homeostatic and IFNγ-dependent programs enrich across primary human tumors, including melanoma, and stratify survival. Single-cell RNA sequencing (RNA-seq) reveals enrichment of homeostatic modules in monocytes and DCs from human metastatic melanoma. Suppressor-of-cytokine-2 (SOCS2) protein, a conserved program transcript, is expressed by mononuclear phagocytes infiltrating primary melanoma and is induced by IFNγ. SOCS2 limits adaptive anti-tumoral immunity and DC-based priming of T cells in vivo, indicating a critical regulatory role. These findings link immune homeostasis to key determinants of anti-tumoral immunity and escape, revealing co-opting of tissue-specific immune development in the tumor microenvironment.

Global consensus process to establish a core dataset for hidradenitis suppurativa registries.

BACKGROUND: Several registries for hidradenitis suppurativa (HS) already exist in Europe and the USA. There is currently no global consensus on a core dataset (CDS) for these registries. Creating a global HS registry is challenging, owing to logistical and regulatory constraints, which could limit opportunities for global collaboration as a result of differences in the dataset collected. The solution is to encourage all HS registries to collect the same CDS of information, allowing registries to collaborate. OBJECTIVES: To establish a core set of items to be collected by all HS registries globally. The core set will cover demographic details, comorbidities, clinical examination findings, patient-reported outcome measures and treatments. METHODS: Beginning in September 2022, 20 participants - including both clinicians with expertise in HS and patient advocates - from eight countries across three continents participated in a Delphi process consisting of four rounds of voting, with all participants completing each round. A list of potential items for inclusion in the core set was generated from the relevant published literature, including systematic reviews of comorbidities in HS, clinical and examination findings, and epidemiology. For disease severity and progression items, the Hidradenitis SuppuraTiva Core outcome set International Collaboration (HiSTORIC) core set and other relevant instruments were considered for inclusion. This resulted in 47 initial items. Participants were invited to suggest additional items to include during the first round. Anonymous feedback was provided to inform each subsequent round of voting to encourage consensus. RESULTS: The eDelphi process established a CDS of 48 items recommended for inclusion in all HS registries globally. CONCLUSIONS: The routine adoption of this CDS in current and future HS registries should allow registries in different parts of the world to collaborate, enabling research requiring large numbers of participants.

Discrepancies in hidradenitis suppurativa lesion characterization by providers and patients.

BACKGROUND: The hidradenitis suppurativa (HS) clinical response (HiSCR) has come under scrutiny as several HS clinical trials failed to meet primary endpoints with high placebo responses. This may be due to limitations of the tool and raters' ability to accurately characterize and count lesions, rather than lack of efficacy of the studied drug. Due to HS lesion complexity and potential differences in rater training, it was hypothesized that there would be discrepancies in how providers characterize and count lesions for HS clinical trials. OBJECTIVE: To evaluate how HS providers and patients name and count HS lesions and to identify discrepancies among providers to initiate the development of consensus-driven guidance for HS rater training. METHODS: An online survey was distributed to the members of HIdradenitis SuppuraTiva cORe outcomes set International Collaboration (HISTORIC). Respondents were asked to classify lesion images composed of multiple and different morphology types and answer questions regarding inclusion of associated dermatological conditions. RESULTS: Forty-seven HISTORIC members responded (29 providers; 18 patients). There was variability in how respondents classified HS lesions. Of 12 questions containing images, four had ≥50% of respondents choosing the same answer. With an image of a lesion composed of different morphologies, 45% of providers counted it as a single lesion and 45% counted it as multiple distinct lesions. With an image of multiple interconnected draining tunnels, 7% of providers classified it as a single draining tunnel while 79% categorized it as multiple draining tunnels with the number estimated by visual inspection. There was also variability in deciding whether lesions occurring in associated conditions should be considered separately or included in HS lesion counts. Patient responses were also variable. CONCLUSIONS: The result of the current study reaffirms the gap in how providers characterize and count HS lesions for clinical trials and the need to develop consensus-driven rater training related to HS outcome measures.

Single-cell transcriptomics suggest distinct upstream drivers of IL-17A/F in hidradenitis versus psoriasis.

BACKGROUND: On the basis of the mounting evidence that type 17 T (T17) cells and increased IL-17 play a key role in driving hidradenitis suppurativa (HS) lesion development, biologic agents used previously in psoriasis that block signaling of IL-17A and/or IL-17F isoforms have been repurposed to treat HS. OBJECTIVE: Our research aimed to characterize the transcriptome of HS T17 cells compared to the transcriptome of psoriasis T17 cells, along with their ligand-receptor interactions with neighborhood immune cell subsets. METHODS: Single-cell data of 12,300 cutaneous immune cells from 8 deroofing surgical HS skin samples including dermal tunnels were compared to single-cell data of psoriasis skin (19,525 cells from 11 samples) and control skin (11,920 cells from 10 samples). All single-cell data were generated by the same protocol. RESULTS: HS T17 cells expressed lower levels of IL23R and higher levels of IL1R1 and IL17F compared to psoriasis T17 cells (P < .05). HS Treg cells expressed higher levels of IL1R1 and IL17F compared to psoriasis Treg cells (P < .05). Semimature dendritic cells were the major immune cell subsets expressing IL1B in HS, and IL-1ß ligand-receptor interactions between semimature dendritic cells and T17 cells were increased in HS compared to psoriasis (P < .05). HS dermal tunnel keratinocytes expressed inflammatory cytokines (IL17C, IL1A, IL1B, and IL6) that differed from the HS epidermis keratinocytes (IL36G) (P < .05). IL6, which synergizes with IL1B to maintain cytokine expression in T17 cells, was mainly expressed by fibroblasts in HS, which also expressed IL11+ inflammatory fibroblast genes (IL11, IL24, IL6, and POSTN) involved in the paracrine IL-1/IL-6 loop. CONCLUSION: The IL-1ß-T17 cell cytokine axis is likely a dominant pathway in HS with HS T17 cells activated by IL-1ß signaling, unlike psoriasis T17 cells, which are activated by IL-23 signaling.

External Validation of the IHS4-55 in a European Antibiotic-Treated Hidradenitis Suppurativa Cohort.

BACKGROUND: Previously, a new dichotomous outcome was developed, calculated as 55% reduction in the International Hidradenitis Suppurativa 4 (IHS4-55) score. It was validated in datasets of adalimumab and placebo-treated HS patients. External validation is an important aspect of clinical outcomes. OBJECTIVES: We aimed to externally validate the novel dichotomous IHS4-55 in a non-biologic treated dataset of HS patients. METHODS: Data from a previously published European-wide prospective clinical study of antibiotic treatment of HS patients were used to assess the association of IHS4-55 achievement with individual reduction in inflammatory nodules, abscesses, and draining tunnels. Moreover, the associations between IHS4-55 positivity and achievement of the minimal clinically important differences (MCIDs) for Dermatology Life Quality Index (DLQI), Numerical Rating Scale (NRS) Pain, and NRS Pruritus were analyzed. RESULTS: Data were obtained from 283 individual patients, of which 36.4% (103/283) were treated with clindamycin and rifampicin and 63.6% (180/283) with tetracyclines for 12 weeks. Achievers of the IHS4-55 demonstrated a significant reduction the counts of inflammatory nodules, abscesses, and draining tunnels (all p < 0.001). Additionally, IHS4-55 achievers had an odds ratio for achieving the MCID of DLQI, NRS Pain, and NRS Pruritus of 2.16 (95% CI 1.28-3.65, p < 0.01), 1.79 (95% CI 1.10-2.91, p < 0.05), and 1.95 (95% CI 1.18-3.22, p < 0.01), respectively. CONCLUSIONS: This study shows the external validity of the novel IHS4-55 by demonstrating a significant association between IHS4-55 achievement and a reduction in inflammatory lesion counts as well as achievement of MCIDs for DLQI, NRS Pain, and NRS Pruritus in an antibiotic-treated cohort. These findings support the use of the IHS4-55 as a novel primary outcome measure in clinical trials.

Development and validation of IHS4-55, an IHS4 dichotomous outcome to assess treatment effect for hidradenitis suppurativa.

BACKGROUND: Validated, inclusive and easy-to-use outcomes for hidradenitis suppurativa are essential both in the clinical trial setting and clinical practice. The continuous IHS4 is a validated tool that dynamically assesses nodules/abscesses/draining tunnels and classifies disease severity as mild/moderate/severe. However, dichotomous outcomes are often required for clinical trials reporting. OBJECTIVE: To develop and validate a dichotomous outcome based on IHS4 that can be used in clinical trial settings and day-to-day clinical practice. METHODS: De-identified data from the PIONEER-I and -II studies were accessed through Vivli. Potential IHS4 thresholds were analysed using baseline to Week 12 data from adalimumab- and placebo-treated hidradenitis suppurativa patients in the PIONEER-I trial. The final threshold was chosen based on its ability to discriminate between patients treated with adalimumab or placebo and its association with reduction in inflammatory lesions. The final threshold was validated using data from baseline to Week 12 from adalimumab- and placebo-treated hidradenitis suppurativa patients in both the PIONEER-II and the combined PIONEER-I and -II studies. RESULTS: The best performing cut-off for the IHS4 was a 55% reduction of the IHS4 score (IHS4-55). Patients who achieved the IHS4-55 had an odd's ratio of 2.00 [95%-CI 1.26-3.18, p = 0.003], 2.79 (95%-CI 1.76-4.43, p < 0.001) and 2.16 (95%-CI 1.43-3.29, p < 0.001) for being treated with adalimumab rather than placebo in PIONEER-I, PIONEER-II and the combined dataset, respectively. Additionally, the achievement of the IHS4-55 was associated with a significant reduction in inflammatory nodules, abscesses and draining tunnels in all analysed datasets. CONCLUSIONS: IHS4-55, a novel dichotomous IHS4 version, based on a 55% reduction of the total score was developed. The IHS4-55 performs similarly to the HiSCR in discriminating between adalimumab- and placebo-treated hidradenitis suppurativa patients and shows significant associations with reductions in lesion counts. Moreover, the IHS4-55 addresses some of the HiSCR drawbacks by dynamically including draining tunnels in a validated manner. By allowing the analysis of hidradenitis suppurativa patients with an abscess and nodule count below 3 but many draining tunnels, this outcome measure will improve inclusivity in clinical trials.

Factors associated with treatment satisfaction in patients with hidradenitis suppurativa: results from the Global VOICE project.

BACKGROUND: Nearly half of patients with hidradenitis suppurativa (HS) report dissatisfaction with their treatment. However, factors related to treatment satisfaction have not been explored. OBJECTIVES: To measure associations between treatment satisfaction and clinical and treatment-related characteristics among patients with HS. METHODS: Treatment satisfaction was evaluated utilizing data from a cross-sectional global survey of patients with HS recruited from 27 institutions, mainly HS referral centres, in 14 different countries from October 2017 to July 2018. The primary outcome was patients' self-reported overall satisfaction with their current treatments for HS, rated on a five-point scale from 'very dissatisfied' to 'very satisfied'. RESULTS: The final analysis cohort comprised 1418 patients with HS, most of whom were European (55%, 780 of 1418) or North American (38%, 542 of 1418), and female (85%, 1210 of 1418). Overall, 45% (640 of 1418) of participants were either dissatisfied or very dissatisfied with their current medical treatment. In adjusted analysis, patients primarily treated by a dermatologist for HS had 1·99 [95% confidence interval (CI) 1·62-2·44, P < 0·001] times the odds of being satisfied with current treatment than participants not primarily treated by a dermatologist. Treatment with biologics was associated with higher satisfaction [odds ratio (OR) 2·36, 95% CI 1·74-3·19, P < 0·001] relative to treatment with nonbiologic systemic medications. Factors associated with lower treatment satisfaction included smoking (OR 0·78, 95% CI 0·62-0·99; active vs. never), depression (OR 0·69, 95% CI 0·54-0·87), increasing number of comorbidities (OR 0·88 per comorbidity, 95% CI 0·81-0·96) and increasing flare frequency. CONCLUSIONS: There are several factors that appear to positively influence satisfaction with treatment among patients with HS, including treatment by a dermatologist and treatment with a biologic medication. Factors that appear to lower treatment satisfaction include active smoking, depression, accumulation of comorbid conditions and increasing flare frequency. Awareness of these factors may support partnered decision making with the goal of improving treatment outcomes. What is already known about this topic? Nearly half of patients with hidradenitis suppurativa report dissatisfaction with their treatments. What does this study add? Satisfaction with treatment is increased by receiving care from a dermatologist and treatment with biologics. Satisfaction with treatment is decreased by tobacco smoking, accumulation of comorbid conditions including depression, and higher flare frequency. What are the clinical implications of this work? Awareness of the identified factors associated with poor treatment satisfaction may support partnered decision making and improve treatment outcomes.

Comorbidity screening in hidradenitis suppurativa: Evidence-based recommendations from the US and Canadian Hidradenitis Suppurativa Foundations.

BACKGROUND: Hidradenitis suppurativa (HS) is associated with comorbidities that contribute to poor health, impaired life quality, and mortality risk. OBJECTIVE: To provide evidence-based screening recommendations for comorbidities linked to HS. METHODS: Systematic reviews were performed to summarize evidence on the prevalence and incidence of 30 comorbidities in patients with HS relative to the general population. The screening recommendation for each comorbidity was informed by the consistency and quality of existing studies, disease prevalence, and magnitude of association, as well as benefits, harms, and feasibility of screening. The level of evidence and strength of corresponding screening recommendation were graded by using the Strength of Recommendation Taxonomy (SORT) criteria. RESULTS: Screening is recommended for the following comorbidities: acne, dissecting cellulitis of the scalp, pilonidal disease, pyoderma gangrenosum, depression, generalized anxiety disorder, suicide, smoking, substance use disorder, polycystic ovary syndrome, obesity, dyslipidemia, diabetes mellitus, metabolic syndrome, hypertension, cardiovascular disease, inflammatory bowel disease, spondyloarthritis, and sexual dysfunction. It is also recommended to screen patients with Down syndrome for HS. The decision to screen for specific comorbidities may vary with patient risk factors. The role of the dermatologist in screening varies according to comorbidity. LIMITATIONS: Screening recommendations represent one component of a comprehensive care strategy. CONCLUSIONS: Dermatologists should support screening efforts to identify comorbid conditions in HS.

Diagnosis and management of hidradenitis suppurativa in women.

Hidradenitis suppurativa is a chronic inflammatory disease that disproportionately affects women of childbearing age. Hidradenitis suppurativa is characterized by painful nodules, abscesses, draining dermal tunnels, and scarring with a predilection for intertriginous sites, such as the axilla, groin, and breast regions. Delay in diagnosis and treatment of hidradenitis suppurativa often results in long-term sequelae leading to significant morbidity, and rarely mortality, in these patients. This clinical opinion suggests that obstetrician-gynecologists are uniquely poised to recognize early signs of hidradenitis suppurativa during routine well-woman examinations and initiate treatment or referral to dermatology. Herein, we provide clinical pearls for obstetrician-gynecologists caring for female patients with hidradenitis suppurativa, including strategies for comprehensive management and recommendations to improve the comfort of patients with hidradenitis suppurativa during examinations.

Proceeding report of the Fourth Symposium on Hidradenitis Suppurativa Advances 2019.

The Fourth Annual Symposium on Hidradenitis Suppurativa (SHSA) took place on November 1-3, 2019, at the Westin Book Cadillac Hotel in Detroit, Michigan. This symposium was a joint meeting of the US Hidradenitis Suppurativa Foundation and the Canadian Hidradenitis Suppurativa Foundation. This cross-disciplinary meeting with experts from around the world was an opportunity to discuss the most recent advances in the study of hidradenitis suppurativa (HS) pathogenesis, clinical trials, classification, scoring systems, complementary/alternative medical treatments, diet, pain management, surgical and laser treatment, and ultrasonographic assessment. A special preconference workshop was held on the use of neodymium-doped yttrium-aluminum-garnet laser hair reduction, sinus tract deroofing, and carbon dioxide laser excision with ultrasonographic mapping and tumescent anesthesia for the treatment of HS. The focused workshops on establishing an HS clinic, setting up an HS support group, the Hidradenitis Suppurativa Prospective Observational Registry and Biospecimen Repository, and wound care were held during the meeting. A special program called HS Ambassadors was established for patients who may have questions about the conference presentations, and in addition, a meet and greet for patients and HS Ambassadors was arranged. To facilitate networking between those early in their careers and clinical and research experts, a mentoring reception was held.

Pain management in hidradenitis suppurativa and a proposed treatment algorithm.

Pain contributes substantially to reduced quality of life in individuals living with hidradenitis suppurativa (HS). Although improved understanding of HS pathogenesis and treatment has resulted in improved evidence-based HS management guidelines, comprehensive pain management guidelines have yet to be developed. Few HS-specific data exist to guide pharmacologic analgesia; however, recognizing HS pain as either acute or chronic and predominantly nociceptive (aching and gnawing pain due to tissue damage) versus neuropathic (burning-type pain due to somatosensory nervous system dysfunction) provides a conceptual framework for applying outside pain management practices to HS management. This article incorporates the best available evidence from the HS and pain literature to propose an HS pain algorithm that integrates psychological, pharmacologic, and complementary and alternative treatment modalities.

Physician perspectives on complementary and alternative medicine in hidradenitis suppurativa.

Hidradenitis suppurativa (HS) is a chronic and often debilitating inflammatory condition characterized by frequent nodules, abscesses, sinus tracts, and scars impacting the intertriginous areas. Many patients with HS often report limited treatment success and symptom coverage with conventional therapies. Recent studies have reported the widespread use of complementary and alternative medicine (CAM) among patients with HS. In this study, our aim was to examine current physician practice patterns, opinions, and comfort with recommending CAM. Our results indicate that provider comfort and opinions on CAM varied based on the provider's experiences, demographics, and the CAM modality itself. Overall, nearly two-thirds (n = 30, 61.2%) of respondents agreed that CAM and conventional medicine were more effective together than either alone. Meanwhile, 44.9% (n = 22) of respondents routinely recommend CAM while 64.6% (n = 31) of respondents reported that they are routinely asked about CAM. The majority (n = 41, 83.7%) of respondents indicated a lack of scientific evidence in the medical literature as a barrier to recommending CAM along with efficacy concerns (n = 34, 69.4%) and ability to recommend reputable CAM products (n = 32, 65.3%) and practitioners (n = 32, 65.3%). Future investigations are warranted to establish a better understanding of the efficacy and benefit of CAM methods in conjunction with conventional methods.

A Comparison of International Management Guidelines for Hidradenitis Suppurativa.

Hidradenitis suppurativa (HS) is a chronic inflammatory dermatosis that imparts a significant burden on patients and presents a management challenge for healthcare providers. As attention to this debilitating condition has grown over recent years, our understanding of HS pathogenesis and optimal treatment approaches continues to evolve. Nine HS treatment guidelines developed by various expert organizations have been published, encompassing therapeutic modalities ranging from topical agents to systemic therapies to procedural interventions. These guidelines demonstrate significant overlap in treatment recommendations and have all been published within the last 5 years. Therefore, we aim to compare and synthesize the recommendations of international HS treatment guidelines and to encourage inter-organizational communication for the development of consensus or staggered publication of recommendations for HS management.

What causes hidradenitis suppurativa ?-15 years after.

The 14 authors of the first review article on hidradenitis suppurativa (HS) pathogenesis published 2008 in EXPERIMENTAL DERMATOLOGY cumulating from the 1st International Hidradenitis Suppurativa Research Symposium held March 30-April 2, 2006 in Dessau, Germany with 33 participants were prophetic when they wrote "Hopefully, this heralds a welcome new tradition: to get to the molecular heart of HS pathogenesis, which can only be achieved by a renaissance of solid basic HS research, as the key to developing more effective HS therapy." (Kurzen et al. What causes hidradenitis suppurativa? Exp Dermatol 2008;17:455). Fifteen years later, there is no doubt that the desired renaissance of solid basic HS research is progressing with rapid steps and that HS has developed deep roots among inflammatory diseases in Dermatology and beyond, recognized as "the only inflammatory skin disease than can be healed". This anniversary article of 43 research-performing authors from all around the globe in the official journal of the European Hidradenitis Suppurativa Foundation e.V. (EHSF e.V.) and the Hidradenitis Suppurativa Foundation, Inc (HSF USA) summarizes the evidence of the intense HS clinical and experimental research during the last 15 years in all aspects of the disease and provides information of the developments to come in the near future.

Exploring changes in placebo treatment arms in hidradenitis suppurativa randomized clinical trials: A systematic review.

BACKGROUND: Hidradenitis suppurativa (HS) is characterized by recurrent, painful nodules in flexural areas. OBJECTIVE: The objective of this study was to explore the placebo response in HS randomized clinical trials and to compare it briefly with the placebo response in psoriasis and atopic dermatitis. METHODS: A Cochrane Review on interventions in HS was used as a starting point, and a systematic review was then undertaken by using the PubMed database, yielding 7 HS randomized clinical trials for inclusion in this study. RESULTS: This review demonstrates that there is a robust placebo response in HS that is most marked in physical signs but also marked in pain responses. LIMITATIONS: Multiple outcome measures utilized in these studies and reporting bias limited this review. CONCLUSION: This large placebo response has implications for clinical trial design. This knowledge can also help deliver improved clinical care by forming the basis of nonpharmacologic treatments and help optimize current medication use to maximize the placebo effect.

Evaluating patients' unmet needs in hidradenitis suppurativa: Results from the Global Survey Of Impact and Healthcare Needs (VOICE) Project.

BACKGROUND: A needs assessment for patients with hidradenitis suppurativa (HS) will support advancements in multidisciplinary care, treatment, research, advocacy, and philanthropy. OBJECTIVE: To evaluate unmet needs from the perspective of HS patients. METHODS: Prospective multinational survey of patients between October 2017 and July 2018. RESULTS: Before receiving a formal HS diagnosis, 63.7% (n = 827) of patients visited a physician ≥5 times. Mean delay in diagnosis was 10.2 ± 8.9 years. Patients experienced flare daily, weekly, or monthly in 23.0%, 29.8%, and 31.1%, respectively. Most (61.4% [n = 798]) rated recent HS-related pain as moderate or higher, and 4.5% described recent pain to be the worst possible. Access to dermatology was rated as difficult by 37.0% (n = 481). Patients reported visiting the emergency department and hospital ≥5 times for symptoms in 18.3% and 12.5%, respectively. An extreme impact on life was reported by 43.3% (n = 563), and 14.5% were disabled due to disease. Patients reported a high frequency of comorbidities, most commonly mood disorders. Patients were dissatisfied with medical or procedural treatments in 45.9% and 34.6%, respectively. LIMITATIONS: Data were self-reported. Patients with more severe disease may have been selected. CONCLUSION: HS patients have identified several critical unmet needs that will require stakeholder collaboration to meaningfully address.

Proceeding report of the third symposium on Hidradenitis Suppurativa advances (SHSA) 2018.

The 3rd Annual Symposium on Hidradenitis Suppurativa Advances (SHSA) took place on 12-14 October 2018 at the Women's College Hospital in Toronto, Ontario, Canada. This symposium was a joint meeting of the Hidradenitis Suppurativa Foundation (HSF) founded in the USA and the Canadian Hidradenitis Suppurativa Foundation (CHSF). This cross-disciplinary meeting with experts from around the world was an opportunity to discuss the most recent advances in the study of hidradenitis suppurativa pathogenesis, epidemiology, classification, scoring systems, radiologic diagnosis, treatment approaches and psychologic assessment. Two special sessions this year were HS as a systemic disease and HS management guidelines. There were focused workshops on wound healing and ultrasound. There were two sessions primarily for patients and their families in the HS School programme: One workshop focused on mindfulness, and the second involved discussion among clinicians and patients about various disease aspects and the latest management. To facilitate networking between clinical and research experts and those early in their career, a mentoring breakfast was held.

Proceeding report of the Second Symposium on Hidradenitis Suppurativa Advances (SHSA) 2017.

The 2nd Annual Symposium on Hidradenitis Suppurativa Advances (SHSA) took place on 03-05 November 2017 in Detroit, Michigan, USA. This symposium was a joint meeting of the Hidradenitis Suppurativa Foundation (HSF Inc.) founded in the USA, and the Canadian Hidradenitis Suppurativa Foundation (CHSF). This was the second annual meeting of the SHSA with experts from different disciplines arriving from North America, Europe and Australia, in a joint aim to discuss most recent innovations, practical challenges and potential solutions to issues related in the management and care of Hidradenitis Suppurativa patients. The last session involved clinicians, patients and their families in an effort to educate them more about the disease.

North American clinical management guidelines for hidradenitis suppurativa: A publication from the United States and Canadian Hidradenitis Suppurativa Foundations: Part II: Topical, intralesional, and systemic medical management.

Hidradenitis suppurativa is a severe and debilitating dermatologic disease. Clinical management is challenging and consists of both medical and surgical approaches, which must often be combined for best outcomes. Therapeutic approaches have evolved rapidly in the last decade and include the use of topical therapies, systemic antibiotics, hormonal therapies, and a wide range of immunomodulating medications. An evidence-based guideline is presented to support health care practitioners as they select optimal medical management strategies and is reviewed in this second part of the management guidelines. A therapeutic algorithm informed by the evidence available at the time of the review is provided.