PASH syndrome (pyoderma gangrenosum, acne and hidradenitis suppurativa): a disease with genetic heterogeneity

Insights into the Pathogenesis of Pyoderma Gangrenosum

Pyoderma gangrenosum (PG) is a neutrophilic dermatosis of unclear etiology. Numerous theories of its underlying pathogenesis have been proposed, including external triggers, neutrophilic dysfunction, complement activation, and autoimmunity, as well as a possible component of underlying genetic susceptibility. This review seeks to synthesize current understanding of the pathogenesis of PG and integrate interactions between the multitude of implicated host immune pathways to guide and inform future directions into the treatment of PG.

Pyoderma gangrenosum, acne, and suppurative hidradenitis (PASH) syndrome: a single-institution case series with a focus on management

BACKGROUND

Pyoderma gangrenosum, acne, and suppurative hidradenitis (PASH) syndrome is a rare condition characterized by clinical features of all three dermatologic conditions. The management of PASH syndrome is difficult, with no consensus on treatment guidelines. Since PASH syndrome can increase morbidity and adversely impact quality of life, better characterization of effective therapies is needed.

METHODS

A retrospective cohort study was conducted to identify all patients with pyoderma gangrenosum (PG) treated at The Ohio State University Wexner Medical Center between 2015 and 2021. PG diagnosis was confirmed via PARACELSUS score. Subsequent chart review identified eight patients with concomitant hidradenitis suppurativa (HS) and acne who were clinically diagnosed with PASH syndrome.

RESULTS

Eight patients were clinically diagnosed with PASH syndrome based on their clinical presentation at our institution. Seven patients had failed some type of medical therapy prior to presentation, including topical corticosteroids, oral corticosteroids, oral antibiotics, and biologics. One patient had also tried surgical drainage at an outside institution. Six patients were effectively treated with biologics, usually in combination with other therapies. One patient experienced improvement of her skin lesions after diagnosis and treatment of her underlying hematologic malignancy.

CONCLUSIONS

Medical management with biologics in combination with corticosteroids and/or antibiotics was effective in the management of most patients. Diagnosis and treatment of an underlying condition should be prioritized in refractory cases. If workup is negative, surgical management may be considered. Further investigation with a greater number of patients is required to develop management guidelines for PASH syndrome.

Hidradenitis suppurativa: Detangling phenotypes and identifying common denominators

Hidradenitis suppurativa (HS) is a chronic inflammatory skin disease with a severe impact on patients' quality of life through its recurrent and painful nature, as well as its comorbidity burden. The shift in the pathogenic paradigm from a condition of the apocrine glands to an autoinflammatory disease associated with follicular destruction has rendered its understanding difficult, as there are still large gaps in pinpointing the underlying mechanisms, which cannot currently explain the existing clinical variation and as a result, translate into suboptimal therapy. Multifactorial involvement is hypothesized, with an implication of genetic mutations, microbiome dysbiosis, cytokine upregulation and environmental factors. Clinical observation is fundamental for diagnosis, however, the marked heterogeneity in presentation leads to delays in detection and challenges in treatment selection, showcasing clear limits in defining the link between genetic aspects of HS, the role of epigenetic factors and its pathogenic pathways. There have been attempts to formulate phenotypes that could aid in prognostication and management, however, current classification schemata show significant overlap and no validation through longitudinal studies. In this context, nomenclature poses a great challenge due to the lack of global agreement in the definition of lesions, which should be addressed by future research to enable simplified recognition and allow for more precise severity scoring. This could be complemented by the addition of extra dermatologic findings or paraclinical assessment in constructing phenotypes. The development of valid, predictive and reliable classifications of HS may lead to an improvement in comprehending its pathophysiology, favouring a more personalized approach in management. This could be achieved through consensus in the characterization of clinical features and data gathering, as well as validation attempts for described phenotypes. Ultimately, the genotype-endotype-phenotype correlation in HS requires targeted, systematic inquiries and should be addressed more largely to broaden the perspective on this debilitating entity.

Molecular analysis of inflammatory diseases

If we try to describe the search for molecular actors involved in inflammatory diseases, the picture best representing this task is a mission to unexplored worlds. However, researchers nowadays have powerful tools to support this journey to the complexity of the unknown: Next generation Sequencing technologies have provided a plethora of data describing the different OMICs possibly involved in the different inflammatory diseases. Here we focused on autoinflammatory skin diseases showing the progress of OMICs-related findings in the understanding of Syndromic HS pathogenesis. We described the studies reporting possible genotype/phenotype correlation in PASH and PAPASH patients (both unrelated or familial cases), highlighting those just genetic variations associated with the diseases have been observed, but the information on common pathways shared by PASH and PAPASH patients were lacking, thus rendering difficult to decipher the common molecular basis of these autoinflammatory conditions. Aimed at filling this gap of knowledge, we proposed an integrated OMICs approach able to identify common pathways shared by subjects suffering from PASH and PAPASH: pathway-based whole sequencing analysis allowed the identification of 4 pathways, keratinization, formation of the cornified envelope steroid metabolism and ​​Vitamin D metabolism, disrupted in PASH and PAPASH patients. Finally, we mentioned the novel bioinformatic platform, named PlatOMICs, capable of integrating OMICs experimental findings also with the ones already reported in public repositories supporting the efforts of the researchers and clinicians to discover molecular pathways shared by individuals suffering of a disease, confronting, and integrating the bench findings with the in-silico ones.

Pyoderma Gangrenosum, Acne, and Hidradenitis Suppurativa Syndrome: A Case Report and Literature Review

Pyoderma gangrenosum, acne, and hidradenitis suppurativa syndrome is a rare inflammatory disease characterized by pyoderma gangrenosum (PG), mild to severe facial acne, and hidradenitis suppurativa (HS). It only affects the skin and represents cutaneous characteristics of a spectrum of autoinflammation. Lack of pyogenic sterile arthritis (PA) distinguishes the pyoderma gangrenosum, acne, and hidradenitis suppurativa (PASH) syndrome from pyogenic arthritis, pyoderma gangrenosum, acne, and hidradenitis suppurativa (PA-PASH), pyoderma gangrenosum, acne, hidradenitis suppurtiva, and ankylosing spondylitis (PASS), and pyogenic arthritis, pyoderma gangrenosum, and acne (PAPA) syndromes. The exact etiology and pathogenesis of PASH syndrome remain unknown. Both PG and HS are contained in the spectrum of neutrophilic dermatitis, which is considered as an autoinflammatory syndrome. From a pathophysiological point of view, they show similar mechanisms, including neutrophil-rich cutaneous infiltration and overexpression of the interleukin-1 (IL-1) family. These findings provide guidance for these intractable diseases. In this review, we described a case of PASH syndrome in a patient who initially failed to respond to immunosuppressive treatment but responded to a combination of colchicine and thalidomide. We reviewed the relevant literature that focuses on PASH syndrome management.

Variant Enrichment Analysis to Explore Pathways Functionality in Complex Autoinflammatory Skin Disorders through Whole Exome Sequencing Analysis

The challenge of unravelling the molecular basis of multifactorial disorders nowadays cannot rely just on association studies searching for potential causative variants shared by groups of patients and not present in healthy individuals; indeed, association studies have as a main limitation the lack of information on the interactions between the disease-causing variants. Thus, new genomic analysis tools focusing on disrupted pathways rather than associated gene variants are required to better understand the complexity of a disease. Therefore, we developed the Variant Enrichment Analysis (VEA) workflow, a tool applicable for whole exome sequencing data, able to find differences between the numbers of genetic variants in a given pathway in comparison with a reference dataset. In this study, we applied VEA to discover novel pathways altered in patients with complex autoinflammatory skin disorders, namely PASH (n = 9), 3 of whom are overlapping with SAPHO) and PAPASH (n = 3). With this approach we have been able to identify pathways related to neutrophil and endothelial cells homeostasis/activations, as disrupted in our patients. We hypothesized that unregulated neutrophil transendothelial migration could elicit increased neutrophil infiltration and tissue damage. Based on our findings, VEA, in our experimental dataset, allowed us to predict novel pathways impaired in subjects with autoinflammatory skin disorders.

Pyoderma Gangrenosum and Interleukin Inhibitors: A Semi-Systematic Review

BACKGROUND

Pyoderma gangrenosum (PG) is a rare ulcerating skin disease associated with multiple comorbidities and increased mortality. In recent decades, newer biologics such as interleukin inhibitors have been used to treat PG; however, the literature is scarce, consisting predominantly of case reports and caseseries. The aim of our review was to evaluate the effectiveness and safety of interleukin inhibitors for the treatment of PG in adults.

SUMMARY

A literature search was conducted using search terms related to PG and interleukin inhibitors in databases such as PubMed, Embase, Scopus, Web of Science, and Cochrane Library. The study eligibility criteria included patients diagnosed with PG, over the age of 18, and treated with an interleukin inhibitor. Our study included 60 papers describing 81 patients fulfilling the eligibility criteria. The treatment with interleukin inhibitors resulted in 70% (95% CI 59-80%) response and 57% (95% CI 45-68%) complete response rates, and few (4%) mild adverse events, hence supporting the off-label use for the treatment of recalcitrant PG in adults. The response and complete response rates were 59% (17/29) and 38% (11/29) for anakinra, 64% (7/11) and 55% (6/11) for canakinumab, and 79% (27/34) and 71% (24/34) for ustekinumab, respectively. Limitations include publication bias that might have overestimated the efficacy as successful cases responding to treatment are more likely to be reported than nonresponding cases. Additionally, the heterogeneity of the treatment groups does not allow conclusions of superiority or inferiority of the different interleukin inhibitors to be drawn. Further studies are needed to investigate the efficacy of the different interleukin inhibitors and to investigate the importance of underlying disease for treatment response.

Prevalence and Cutaneous Comorbidity of Acne Vulgaris in the Working Population

Purpose

Although acne vulgaris (AV) is a common disease and can persist into adulthood, there are few large-scale epidemiological studies on the prevalence of acne vulgaris in adults. The aim of our study was to characterise the epidemiology and comorbidity of acne vulgaris in working adults in Germany.

Patients and Methods

Within the framework of a cross-sectional study, a total of 161,269 employees underwent dermatological whole-body examinations in more than 500 German companies between 2001 and 2016. Point prevalence rates for acne vulgaris and further skin diseases and their 95% confidence intervals were calculated and differences between participants with and without acne vulgaris were tested with chi-squared tests.

Results

Mean age was 43.2 years ± 10.9, 55.5% were male. In total, n = 5311 people (3.3%) with acne vulgaris were identified. Prevalence decreased by age. Controlling for age and gender, acne was significantly associated with folliculitis (OR = 1.91; CI: 1.76–2.07), contact dermatitis (OR = 1.74; CI: 1.08–2.81), rosacea (OR = 1.74; CI: 1.40–2.15), pyoderma (OR = 1.58; 1.22–2.06), seborrheic dermatitis (OR = 1.47; CI: 1.27–1.71), hand eczema (OR = 1.34; CI: 1.00–1.76), verruca vulgaris plantaris (OR = 1.29; CI: 1.09–1.51), tinea pedis (OR = 1.27; CI: 1.10–1.47), spider veins (OR = 1.26; CI: 1.16–1.38) and telangiectasia (OR = 1.15; CI: 1.02–1.30).

Conclusion

These data underline the importance of acne vulgaris in the adult population. Further studies to better understand the pathophysiology of AV and its comorbidity in different phases of adulthood would be desirable to develop appropriate guidelines and therapy concepts.

Case Report: PsAPSASH syndrome: an alternative phenotype of syndromic hidradenitis suppurativa treated with the IL-17A inhibitor secukinumab

Syndromic hidradenitis suppurativa (HS) is a form of symptom constellations, which differs from the familial and genetic form and comprises predominantly osteoarticular manifestations. Many forms include pyoderma gangrenosum and acne (PASH), pyogenic arthritis (PAPASH), spondyloarthritis (PASS) and psoriatic arthritis (PsAPASH) and are categorized in the autoinflammatory syndromes. Anti-TNF-α and anti-IL-1a blockade are between the therapeutic approaches that improve skin symptoms and prevent permanent osteoarticular damage. This case report refers to the successful treatment of a mixed phenotype of the aforementioned symptoms using the IL-17A inhibitor secukinumab after initial treatment with adalimumab. The therapy improved both cutaneous and reported osteoarticular symptoms. Different approaches for these recalcitrant HS syndromes are essential in order to achieve long-term remission for those patients.

PASH, PAPASH, PsAPASH, and PASS: The autoinflammatory syndromes of hidradenitis suppurativa

Hidradenitis suppurativa (HS) is a chronic inflammatory disease usually involving the major skin folds characterized by a multifactorial pathogenesis and a wide spectrum of clinical manifestations. It can also rarely present in association with other diseases as complex clinical syndromes, causing additional diagnostic and therapeutic challenges. Different etiopathologic factors contribute to follicular inflammation and suppurative lesions of syndromic HS, including follicular hyperkeratinization and plugging, as well as activation of autoinflammatory pathways. Patients with syndromic HS frequently have a severe disease course, presenting with atypical skin involvement, signs of systemic inflammation, and resistance to conventional treatments. Systematic classification of syndromic HS is based on clinical, pathogenetic, and genetic factors, but it is constantly evolving due to increased disease awareness. Treatment of syndromic HS is difficult and should be personalized on a case-by-case basis. Investigating syndromic HS can lead to useful insights on genetics and pathogenesis, translating into new clinical approaches for sporadic hidradenitis. We review the classification, clinical presentation, disease associations, and therapeutic management of syndromic HS, focusing mainly on its autoinflammatory syndromes PASH, PAPASH, PsAPASH, and PASS.

A Unified Concept of Acne in the PAPA Spectrum Disorders

BACKGROUND

Acne is a common condition. Sometimes acne or acne-like features are a part of autoinflammatory diseases such as PAPA spectrum disorders. Our objective wasto determine whether acne in PAPA spectrum disorders has specific phenotypic traits.

SUMMARY

This is aliterature review on reported cases of patients with PAPA, PAMI, PASH, PAPASH, PsAPASH, PAC or PASS syndrome. Acne was classified into four categories: moderate, severe, nodulocystic, acne fulminans.One hundred patients were included. Age of onset of acne and topography were the same as in acne vulgaris. Acne's phenotype was at least severe (including acne fulminans, nodulocystic and severe) in 83% of cases. Genetic mutations or variants with potential pathological significance were reported in 49 patients. The addition of isotretinoin to biotherapies was required to control acne in several patients.

Phenotypes and Pathophysiology of Syndromic Hidradenitis Suppurativa: Different Faces of the Same Disease? A Systematic Review

BACKGROUND

There is growing evidence that (certain) hidradenitis suppurativa (HS) comorbidities comprise syndromes including HS as a key cutaneous manifestation. These apparently autoinflammatory syndromes and their diagnostic delay might have detrimental effects on affected patients.

METHODS

A systematic review was performed on the databases MEDLINE, EMBASE, and CENTRAL utilizing a standardized extraction form according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

RESULTS

Sixty-four eligible articles on syndromic HS were retrieved. The identified syndromes included already described ones (pyoderma gangrenosum-acne-suppurative hidradenitis, pyogenic arthritis-pyoderma gangrenosum-acne-suppurative hidradenitis, psoriatic arthritis-pyoderma gangrenosum-acne-suppurative hidradenitis, pyoderma gangrenosum-acne vulgaris-hidradenitis suppurativa-ankylosing spondylitis, synovitis-acne-pustulosis-hyperostosis-osteitis) and further novel symptom constellations. Cutaneous signs, including HS lesions, usually precede signs from other organs. The cutaneous signs of a considerable proportion of patients appear refractory to conventional treatment, and monotherapy with biologics does not suffice to sustain remission.

CONCLUSION

The results are subsequently discussed with focus on the pathophysiology and treatment of the detected syndromes. The dermatologist's role in the precise diagnosis and early treatment administration of HS is pivotal. The purpose of the treatment should be the effective prevention or delay of the autoinflammatory march and its irreversible consequences.

PAPA spectrum disorders

Pyogenic arthritis, pyoderma gangrenosum (PG) and acne (PAPA) syndrome is an autosomal dominant autoinflammatory syndrome due to mutations in proline-serine-threonine phosphatase interacting protein 1 (PSTPIP1) gene and presenting with cutaneous and articular manifestations. Other autoinflammatory syndromes caused by mutations in PSTPIP1 gene or characterized by clinical findings overlapping with those found in PAPA syndrome have been recently included in the group of PAPA spectrum disorders. These disorders are PASH (PG, acne and hidradenitis suppurativa [HS]), PAPASH (PASH associated with pyogenic sterile arthritis), PsAPASH (PASH combined with psoriatic arthritis [PsA], PASS (PG, acne, ankylosing spondylitis, with or without HS), PAC (PG, acne and ulcerative colitis [UC]) and PAMI syndrome (PSTPIP1-associated myeloid-related-proteinemia inflammatory syndrome). Except for PAPA and PAMI, no specific pathogenetic mutations have been identified in these syndromes. Dermatologists should be aware that PG, acne and HS may represent cutaneous signs hiding the presence of these rare entities. Systemic corticosteroids, a number of immunosuppressants and biologics, such as interleukin (IL)-1 antagonists and tumour necrosis factor (TNF) α inhibitors, are nowadays therapy for these diseases. A pathogenesis-driven treatment is the near future in the management of these conditions.

Prevalence and cutaneous comorbidities of hidradenitis suppurativa in the German working population

The association of hidradenitis suppurativa with other skin diseases has not yet been investigated in larger studies based on dermatological exams. The objectives of this study are to determine the prevalence and cutaneous comorbidities of hidradenitis suppurativa in the German working population. Between 2014 and 2017, 20,112 people in 343 German companies were examined for the presence of clinical features of hidradenitis suppurativa within the framework of a cross-sectional epidemiological study based on whole-body examinations. In addition, all cutaneous comorbidities were recorded. Point prevalence was calculated and the differences between individuals with and without hidradenitis suppurativa were determined by bivariate analysis. All statistical procedures were performed using SPSS 23.0 for Windows. Of 20,112 people examined, mean age was 43.6 ± 10.5 years; 52.3% were male. In total, n = 57 people (0.3%) with hidradenitis suppurativa were identified; 61.4% (n = 35) being male. In addition, non-inflammatory hidradenitis suppurativa-related lesions were found in 674 other individuals. In a bivariate comparison, patients with hidradenitis suppurativa showed significantly more frequently the following cutaneous comorbidities: acne vulgaris, psoriasis, seborrhoeic dermatitis, excoriations, and folliculitis. We determined a point prevalence of hidradenitis suppurativa of 0.3%. Since we have examined the working population, the healthy worker effect, which could have led to underestimation of prevalence, cannot be ruled out. The point prevalence of 0.3% for employed people in Germany and a prevalence of 3.0% for inflammatory and non-inflammatory hidradenitis suppurativa-related lesions show that hidradenitis suppurativa is an important disease for the whole health system.

Inter-rater reliability of phenotypes and exploratory genotype-phenotype analysis in inherited hidradenitis suppurativa

BACKGROUND

Genotype-phenotype correlation measures the correlation between the presence of a physical trait with a group of similar mutations but is dependent on reliable phenotyping. It can provide information on disease pathogenesis, future disease progression, severity or activity. Such indicators would be valuable in hidradenitis suppurativa (HS).

OBJECTIVES

To assess inter-rater reliability (IRR) of HS clinical phenotypes and perform exploratory genotype-phenotype correlation in cases of HS with identified sequence variants.

METHODS

Linkage disequilibrium between variants was assessed. Genotype-phenotype correlations were explored using Spearman correlation coefficients. IRR was calculated using Cohen's κ. Correlation between phenotype classifications was assessed using the χ² statistic.

RESULTS

Forty-three sequence variants with clinical information were identified. Clinical phenotypes were classified as LC2 (n = 29; 67%), scarring folliculitis (n = 18; 42%), atypical (n = 38; 88%) and nodular (n = 26; 60%). LC1 phenotype was associated with regular (χ² = 41·289, P < 0·001) and typical (χ² = 29·013, P < 0·001) phenotypes. Cohen's κ was highest for van der Zee and Jemec (0·815), followed by Martorell-Calatayud et al. (0·813), Naasan and Affleck (0·774) and Canoui-Poitrine et al. (0·435) classifications. High linkage disequilibrium was seen between variants of Han Chinese pedigrees. No significant genotype-phenotype correlations were identified.

CONCLUSIONS

These findings may be influenced by selection, publication bias and the assumption that HS is a monogenic disorder. The poor IRR of existing phenotype measures suggests limited utility of existing measures. Further investigations into the correlation of clinical phenotypes with inflammatory biomarkers may aid in prognostic efforts for this disease. What's already known about this topic? Genotype-phenotype correlation can provide information regarding disease pathogenesis and predictions for future disease progression, severity or activity. The identification of such indicators in hidradenitis suppurativa (HS) would be valuable for patients and clinicians alike, given the lack of biomarkers or clinical predictors of disease. What does this study add? Sixty-five sequence variants across 20 separate genes were identified. There was no significant correlation between phenotype classification in four separate classification schema and gene, mutation type or impact on Notch signalling. Utility of current phenotype measurements are limited. The lack of genotype-phenotype correlation in HS is suggestive that the underlying assumption of inherited HS as a monogenic disorder may need revision.

Pyoderma gangrenosum and tumour necrosis factor alpha inhibitors: A semi-systematic review

Pyoderma gangrenosum (PG) is a rare ulcerative skin disease that presents a therapeutic challenge. Tumour necrosis factor alpha (TNFα) inhibitors have been reported to successfully control PG. Our aim was to systematically evaluate and compare the clinical effectiveness of TNFα inhibitors in adults with PG. A literature search including databases such as PubMed, Embase, Scopus, and Web of Science was conducted, using search terms related to PG and TNFα inhibitors. Studies and case reports were included if patients were diagnosed with PG, over the age of 18 and administered TNFα inhibitor. A total of 3212 unique citations were identified resulting in 222 articles describing 356 patients being included in our study. The study we report found an 87% (95% CI: 83%-90%) response rate and a 67% (95% CI: 62%-72%) complete response rate to TNFα inhibitors. No statistically significant differences in the response rates (P = 0.6159) or complete response rates (P = 0.0773) to infliximab, adalimumab, and etanercept were found. In our study TNFα inhibitors demonstrated significant effectiveness with response and complete response rates supporting the use of TNFα inhibitors to treat PG in adults. Our study suggests that there is no significant difference in effectiveness among infliximab, adalimumab, and etanercept.