Role of inflammatory cells, cytokines and matrix metalloproteinases in neutrophil-mediated skin diseases

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.

Molecular Characteristics of Sweet Syndrome: A Systematic Review

Sweet syndrome (SS), originally described as acute febrile neutrophilic dermatosis, is a rare inflammatory skin condition, considered the prototype of neutrophilic dermatoses. It is characterised by the sudden onset of well-defined tender papules, plaques and nodules often accompanied by fever, neutrophilia and elevated markers of inflammation. Several variants have been described both clinically and histopathologically. Classifications include idiopathic, malignancy-associated, and drug-induced SS. The exact pathogenesis of SS is still unclear; however, recent findings have shed light on the role of dermal infiltrating neutrophils-in the context of innate immunity, and signalling pathways related to adaptive immunity. To critically analyse the current molecular landscape of SS and discuss the recent evidence supporting novel potential immune mediators and biological signalling pathways involved in SS pathogenesis. The methodology followed PRISMA guidelines and included two bibliographical databases, searching articles published until 17 December 2023. Titles, abstracts and full text were reviewed independently by two assessors, while other two investigators resolved any opinion differences. Of 3303 records identified through database search, 22 articles met the eligibility criteria for inclusion. We considered experimental studies that performed molecular analysis, in terms of cytokines quantification, gene expression and/or immunofluorescence/immunohistochemistry. As for the latter, only studies aimed at characterising the nature of the inflammatory infiltrate and potential mechanisms leading to distinct forms of cutaneous inflammatory cell influx were included. Overall, we described research on 202 SS patients (177 skin biopsies and 25 blood specimens) revealing the predominant role of neutrophil activation and abnormal proliferation as unifying mechanisms in different SS subtypes. Interestingly, we found that hyperactivation of the IL-1 pathway might occur only in a subset of SS patients and adaptive immunity could also play a role in the pathogenic scenario of SS, with a potential significant role of IL-17 axis. This systematic review provides a wealth of evidence on the molecular landscape of SS, although further research is needed to a deeper understanding of the patho-mechanisms of this rare disease and hopefully lead to targeted therapeutic approaches.

Pyoderma Gangrenosum With Severe Ankle Ankylosis Complicated by Rheumatoid Arthritis Successfully Treated Using Anti-tumor Necrosis Factor: A Case Report

Pyoderma gangrenosum (PG) is a rare dermatosis characterised by necrotic ulcers with a predilection mainly for the lower legs. We report a case of a 67-year-old man with PG and severe ankle ankylosis complicated by rheumatoid arthritis (RA) treated with anti-tumor necrosis factor, adalimumab (ADA). He was referred to our hospital because his right ankle showed severe ulcers and blackening. X-rays of the right ankle and foot showed bone and joint destruction with ankylosis. Initially diagnosed with stasis dermatitis, he was treated, but his condition became increasingly worse. A skin biopsy revealed neutrophilic invasion of the skin tissue, and final diagnosis was PG complicated with RA and ankylosing joint. ADA therapy improved the patient's skin condition and reduced the right ankle pain, although severe right ankle ankylosis progressed during the last follow-up. PG should be considered as a differential in patients with RA and refractory skin ulcers.

Increased Inflammatory Responses in Patients With Active Disseminated Non-Tuberculous Mycobacterial Infection and High Anti-Interferon-Gamma Autoantibodies

Adult-onset immunodeficiency (AOID) is associated with the presence of anti-IFN-γ autoantibodies (auAbs). In disseminated nontuberculous mycobacterial (dNTM) infection with AOID, neutralization of IFN-γ by auAb may play a role in disease susceptibility, but other molecular mechanisms are likely to contribute. In this study, dNTM patients, including inactive, active but non-progressive and active, progressive cases were enrolled to measure plasma anti-IFN-γ auAb by ELISA and underwent whole-blood RNA sequencing. Healthy control individuals were also enrolled. Plasma IL-8 was then quantified to confirm transcriptomic analysis. Results revealed that anti-IFN-γ auAb titers were significantly increased in patients with active stage of disease. Gene expression could separate patients with active infection from individuals with no signs of infection (inactive patients and healthy controls). In active cases, there was over-expression of inflammatory pathways and under-expression of type-2 immunity pathways. Interestingly, increased levels of plasma IL-8 (p=0.0167) not only confirmed gene expression results but also correlated with the presence of neutrophilic dermatitis (p=0.0244). In conclusion, our findings highlight the value of anti-IFN-γ auAb titers for predicting disease reactivity and first propose IL-8 as a promising mediator to be further explored, given its correlation with skin reactive disease, a hallmark of active dNTM infection.

Overview of Neutrophilic Biology, Pathophysiology, and Classification of Neutrophilic Dermatoses

Neutrophilic dermatoses are a group of inflammatory skin conditions characterized by a neutrophilic infiltrate on histopathology with no evidence of infection. These conditions present with a wide range of clinical manifestations, including pustules, bullae, abscesses, papules, nodules, plaques, and ulcers. The classification of neutrophilic dermatoses is based on the localization of neutrophils in the skin. The pathogenic mechanisms of neutrophilic dermatoses involve autoinflammation, neutrophilic dysfunction, clonal somatic mutation and differentiation of the myeloid precursors as encountered in myeloid neoplasm.

Comparative immunohistochemical analysis of inflammatory cytokines in distinct subtypes of Sweet syndrome

Background

A dysregulated immune response has been implicated in Sweet syndrome (SS) pathogenesis; however, cytokine profiles across different conditions associated with SS - including adult-onset immunodeficiency (AOID) due to anti-interferon (IFN)-γ autoantibodies - remain unknown.

Objective

To investigate alterations in inflammatory cytokines in skin lesions of distinct subtypes of SS.

Methods

Skin biopsies were collected from 42 AOID- and 52 non-AOID-associated SS patients and 18 healthy controls. The comparative immunohistochemical study was conducted using monoclonal antibodies against interleukin (IL)-1β, IL-6, IL-17, IFN-γ, and tumor necrosis factor-α on paraffin-embedded sections. The quantitative percentage positivity and intensity were calculated using computer-based image analysis.

Results

The results showed stronger and more diffuse dermal immunoreactivity for IFN-γ and IL-17 in the AOID-associated (p < 0.001 and p < 0.001, respectively) and non-AOID-associated SS (p < 0.001 and p < 0.001, respectively) groups. However, no significant differences in the levels of these two cytokines were observed between the AOID- and non-AOID-associated SS groups. Increased expression of IFN-γ together with IL-17 was also noted in almost all subtypes among non-AOID-associated SS.

Conclusions

These results demonstrate that IFN-γ and IL-17 are implicated in immunopathology of all SS subtypes, including AOID-associated SS, despite the presence of anti-IFN-γ autoantibodies.

Relapse of Ulcerative Colitis with Immune Thrombocytopenia and Pyoderma Gangrenosum Subsequent to Receiving COVID-19 Vaccination

This case illustrates the complex interactions of the immune responses after vaccination and highlights their potential connections to various autoimmune conditions. A 22-year-old man with quiescent ulcerative colitis (UC) presented with abdominal pain, rectal bleeding, and thrombocytopenia 7 days after receiving the third coronavirus disease 2019 mRNA vaccination. Laboratory data confirmed the diagnosis of immune thrombocytopenia. High-dose intravenous immunoglobulin administration boosted the patient's platelet count. Simultaneously, colonoscopy revealed that his UC had relapsed. Although salazosulfapyridine briefly improved his symptoms, his stool frequency worsened one week later. The patient also developed pyoderma gangrenosum. Subsequent treatment with infliximab notably improved both pyoderma gangrenosum and UC.

Genetic mutations in pyoderma gangrenosum, hidradenitis suppurativa, and associated autoinflammatory syndromes: Insights into pathogenic mechanisms and shared pathways

Pyoderma gangrenosum (PG), hidradenitis suppurativa (HS), and the associated autoinflammatory syndromes, including pyogenic arthritis, pyoderma gangrenosum, and acne (PAPA) syndrome, PSTPIP1-associated myeloid-related proteinemia inflammatory (PAMI) syndrome, pyoderma gangrenosum, acne, and hidradenitis suppurativa (PASH) syndrome, and pyogenic arthritis, pyoderma gangrenosum, acne, and suppurative hidradenitis (PAPASH) syndrome are dermatological conditions characterized by chronic inflammation and tissue damage. Recent advances in genetic research have identified specific mutations associated with these disorders, shedding light on their underlying pathogenic mechanisms. This review aims to summarize the current knowledge of identified mutations and presumed pathophysiology in PG, HS, and the associated autoinflammatory syndromes.

New treatment of pyoderma gangrenosum and hidradenitis suppurativa: A review

Pyoderma gangrenosum (PG) and hidradenitis suppurativa (HS) are stubborn inflammatory skin diseases categorized as neutrophilic hypodermal dermatoses. These conditions exhibit connections with other autoinflammatory disorders driven by immune responses. Their pathogenesis is complex, rooted in significant imbalances in both innate and adaptive immune systems, particularly featuring elevated levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-1, IL-8, IL-17, and IL-23. Studies involving skin tissue pathology and serology have indicated that targeting specific cytokines can bring therapeutic benefits. Indeed, many patients in clinical settings have responded positively to such interventions. Yet, given the diverse cytokines in play, focusing on a single one with antibody therapy might not always be effective. When resistance to biologics emerges, a combined approach targeting multiple overactive cytokines with immunosuppressants, for example cyclosporine and Janus kinase inhibitors, could be an option. In the current review, we explore recent therapeutic developments for PG and HS.

Upadacitinib Plus Intensive Granulocyte and Monocyte Adsorptive Apheresis for Ulcerative Colitis Achieved Ulcer Healing for Pyoderma Gangrenosum

A 44-year-old woman who had been diagnosed with ulcerative colitis (UC) at 22 years old was diagnosed with severe flare-up of UC based on endoscopic findings associated with new-onset active pyoderma gangrenosum (PG) on both lower legs after she decided to discontinue UC treatment. Systemic treatment with intravenous prednisolone at 30 mg/day had achieved insufficient response to UC and PG, resulting in a diagnosis of corticosteroid-refractory UC and PG. Combination therapy with upadacitinib at 45 mg/day plus intensive granulocyte and monocyte adsorptive apheresis (GMA) was started to achieve clinical remission of UC. Ten weeks after starting this combination therapy, clinical improvement of UC was achieved with PG ulcer healing on both lower legs. A combination of upadacitinib plus intensive GMA may offer an effective therapeutic option for patients with active PG in addition to UC but has yet to be approved for induction or maintenance treatment of PG worldwide. PG is a dermatological involvement in UC patients that requires attention.

Neutrophil extracellular traps formation in the lesional skin of various types of pyoderma gangrenosum

Pyoderma gangrenosum (PG) is a chronic neutrophilic disorder characterized by recurrent painful ulcers. Aseptic inflammation by neutrophils plays an essential role, and neutrophil extracellular traps (NETs) formation can contribute to the pathogenesis of PG. Seventy-five patients were diagnosed as having PG in our department, among which 58 ulcerative, 4 bullous, 3 pustular and 10 vegetative type. We examined the 20 skin biopsy specimens (11 ulcerative, 3 bullous, 2 pustular and 4 vegetative type), and local NETs formation in various types of PG was compared among each type. The biopsied specimens were double labelled for myeloperoxidase, citrullinated histone H3. Immunofluorescent images indicated that the histopathologic location and depth of NETs formation in PG varied by the clinical subtypes. In ulcerative PG, NETs formation was observed in the upper to deep dermis. In bullous PG, NETs formation was mainly observed in the epidermis. Pustular type showed NETs formation in the epidermis near the pustules, and in vegetative type, showed NETs formation mainly in the upper dermis. These results indicate that NETting neutrophils play an important role in the pathogenesis of various forms of PG, although the location and depth of NETs formation in the skin lesion of PG differ depending on each type. Further studies are necessary to examine what factors identify different clinical features of PG.

Cutaneous manifestations of inflammatory bowel disease: basic characteristics, therapy, and potential pathophysiological associations

Inflammatory bowel disease (IBD) is a chronic inflammatory disease typically involving the gastrointestinal tract but not limited to it. IBD can be subdivided into Crohn's disease (CD) and ulcerative colitis (UC). Extraintestinal manifestations (EIMs) are observed in up to 47% of patients with IBD, with the most frequent reports of cutaneous manifestations. Among these, pyoderma gangrenosum (PG) and erythema nodosum (EN) are the two most common skin manifestations in IBD, and both are immune-related inflammatory skin diseases. The presence of cutaneous EIMs may either be concordant with intestinal disease activity or have an independent course. Despite some progress in research on EIMs, for instance, ectopic expression of gut-specific mucosal address cell adhesion molecule-1 (MAdCAM-1) and chemokine CCL25 on the vascular endothelium of the portal tract have been demonstrated in IBD-related primary sclerosing cholangitis (PSC), little is understood about the potential pathophysiological associations between IBD and cutaneous EIMs. Whether cutaneous EIMs are inflammatory events with a commonly shared genetic background or environmental risk factors with IBD but independent of IBD or are the result of an extraintestinal extension of intestinal inflammation, remains unclear. The review aims to provide an overview of the two most representative cutaneous manifestations of IBD, describe IBD's epidemiology, clinical characteristics, and histology, and discuss the immunopathophysiology and existing treatment strategies with biologic agents, with a focus on the potential pathophysiological associations between IBD and cutaneous EIMs.

Treatment Strategies in Neutrophilic Dermatoses: A Comprehensive Review

Neutrophilic dermatoses (NDs) are a group of noninfectious disorders characterized by the presence of a sterile neutrophilic infiltrate without vasculitis histopathology. Their physiopathology is not fully understood. The association between neutrophilic dermatoses and autoinflammatory diseases has led some authors to propose that both are part of the same spectrum of diseases. The classification of NDs depends on clinical and histopathological features. This review focuses on the recent developments of treatments in these pathologies.

Clinical guidance of pyoderma gangrenosum 2022

Pyoderma gangrenosum (PG) is a rare, neutrophilic skin disease. For the purpose of accurate diagnosis and proper treatment of PG, the Japanese clinical practice guidance for PG developed by the Japanese Dermatological Association was published in 2022. In this guidance, clinical aspects, pathogenesis, current therapies, and clinical questions on PG are described from the viewpoints of current knowledge and evidence-based medicine. Here, the English version of the Japanese clinical practice guidelines for PG is presented and is intended to be widely referred to in the clinical examination and treatment of PG.

Different molecular pathways are disrupted in Pyoderma gangrenosum patients and are associated with the severity of the disease

Pyoderma gangrenosum (PG) is a rare inflammatory skin disease classified within the spectrum of neutrophilic dermatoses. The pathophysiology of PG is yet incompletely understood but a prominent role of genetics facilitating immune dysregulation has been proposed. This study investigated the potential contribution of disrupted molecular pathways in determining the susceptibility and clinical severity of PG. Variant Enrichment Analysis, a bioinformatic pipeline applicable for Whole Exome Sequencing data was performed in unrelated PG patients. Eleven patients were enrolled, including 5 with unilesional and 6 with multilesional PG. Fourteen pathways were exclusively enriched in the "multilesional" group, mainly related to immune system (i.e., type I interferon signaling pathway), cell metabolism and structural functions. In the "unilesional" group, nine pathways were found to be exclusively enriched, mostly related to cell signaling and cell metabolism. Genetically altered pathways involved in immune system biology and wound repair appear to be nodal pathogenic drivers in PG pathogenesis.

Practical aspects of the diagnosis and management of pyoderma gangrenosum

Pyoderma gangrenosum (PG) is a rare autoinflammatory ulcerative neutrophilic skin disease. Its clinical presentation is a rapidly progressing painful skin ulcer with ill-defined borders and surrounding erythema. The pathogenesis of PG is complex and not fully understood. Clinically, patients with PG often have various systemic diseases, the most common being inflammatory bowel disease (IBD) and arthritis. Due to the lack of specific biological markers, diagnosing PG remains difficult, which easily resulting in misdiagnosis. Some validated diagnostic criteria have been applied in clinical practice that facilitate its diagnosis. The treatment of PG currently consists mainly of immunosuppressive and immunomodulatory agents, especially biological agents, which have bright prospects for PG therapy. After the systemic inflammatory response is controlled, the problem of wounds becomes the main contradiction in PG treatment. Surgery is not controversial for PG, increasing evidence shows that with adequate systemic treatment, the benefits of reconstructive surgery for patients are increasing.

SAPHO Syndrome Complicated by Lesions of the Central Nervous System Successfully Treated with Brodalumab

Synovitis-acne-pustulosis-hyperostosis-osteitis (SAPHO) syndrome is a rare disease with an unknown entity that affects the skin and the peripheral and/or axial joints. Here, we report on a patient with SAPHO syndrome complicated by lesions of the central nervous system who was successfully treated with brodalumab, an IL-17 receptor blocker. He had been suffering from arthralgia in the wrists and knees as well as axial symptoms such as back pain and assimilation of cervical vertebrae. He had been treated with corticosteroid, salazosulfapyridine, methotrexate, and bisphosphonate; however, his peripheral and axial articular manifestation were intractable. Recently, biologics predominantly targeting TNF-α is employed for difficult-to-treat SAPHO cases; however, he had been complicated with the lesions of the central nervous system resembling multiple sclerosis (MS), an inflammatory demyelinating disorder in the central nervous system, for which application of TNF-α inhibitor is contraindicated. Alternatively, brodalumab was administered , which promptly ameliorated the articular manifestations without aggravating the lesions of the central nervous system. We propose that this type of IL-17 blockade could be an alternative therapy for DMARDs-resistant SAPHO syndrome.

Successful switching treatment of adalimumab for refractory pyoderma gangrenosum in a patient with rheumatoid arthritis with prior use of tumour necrosis factor inhibitors: A case report and review of the literature

Pyoderma gangrenosum (PG) is a rare chronic skin disease characterised by painful skin ulcers. There are no treatment guidelines for PG, but systemic treatments including biologics are often used. Recently, adalimumab (ADA), a fully human monoclonal antibody against tumour necrosis factor, was approved for refractory PG treatment in Japan. Herein, we report a case of rheumatoid arthritis with refractory PG 2 months after orthopaedic surgery of the foot during treatment with low-dose etanercept and methotrexate. Although adding a moderate dose of glucocorticoid did not improve her PG, the patient showed a remarkable response after switching from etanercept to ADA in a higher dose than that used to treat rheumatoid arthritis. This higher dose of ADA may be effective for the treatment of refractory PG after the failure of other tumour necrosis factor inhibitors.

Clinicopathological features and prognosis of pyoderma gangrenosum in Korea: A single centre, retrospective, observational study over 20 years

BACKGROUND

Pyoderma gangrenosum is a rare autoinflammatory neutrophilic dermatosis that rapidly evolves. However, little is known about the clinicopathological features and prognosis of pyoderma gangrenosum.

AIMS

We aimed to document clinicopathologic and prognostic data of the patients with pyoderma gangrenosum.

METHODS

In this retrospective observational study, we reviewed case records of patients diagnosed with pyoderma gangrenosum between 1999-2019.

RESULTS

Fifty-three patients were identified by reviewing medical records for skin biopsy; of these, 37 were men and 16 were women. Mean age at onset was 43.3 ± 18.5 years. The most frequently affected area was the lower extremities (60.4%), followed by the head and neck (17.0%). The most common subtype was ulcerative (47.2%), followed by bullous (22.6%). 30 cases had underlying diseases and the most common were malignancy (24.5%), followed by inflammatory bowel diseases (18.9%). The proportion of cases with history of trauma were significantly higher in post-operative type (100%) as compared to the bullous type (8.3%). Histologic features of granulation tissue were frequently found in post-operative type (66.7%) and bullous type (58.3%). Granulomas were predominantly found in bullous type (58.3%). Age <60 years appeared to be significantly associated with multiple lesions. Partial-to-complete remission was observed in 40 cases (75.5%). Nine (17.0%) cases experienced recurrence with a median progression-free period of six months (interquartile range of 3.0-9.0 months). Cases with underlying hematologic disorders and the bullous subtype were significantly associated with early recurrence.

LIMITATIONS

This study was a single-centre study with a retrospective design.

CONCLUSION

Pyoderma gangrenosum appears to have ethnic differences. Underlying haematologic disorders and bullous subtype have a worse prognosis. However, the type of histopathology did not correlate with the clinical outcome of pyoderma gangrenosum.

Neutrophilic Dermatosis and Management Strategies for the Inpatient Dermatologist

Purpose of Review

Neutrophilic dermatoses are a heterogeneous group of disorders with significant overlap in associated conditions, clinical presentation, and histopathologic features. This review provides a structural overview of neutrophilic dermatoses that may present in the inpatient setting along with diagnostic work-up and management strategies.

Recent Findings

Sweet's syndrome has been found in patients with coronavirus disease 2019 (COVID-19). Pyoderma gangrenosum (PG) has been shown to be equally associated with ulcerative colitis and Crohn's disease. A clinical trial shows that cyclosporine is equally effective as prednisone in treating PG. Neutrophilic eccrine hidradenitis has been found in the setting of newer antineoplastic medications, such as BRAF inhibitors, as well as in the setting of malignancy without chemotherapy exposure.

Summary

Neutrophilic dermatoses are a rare and complex group of dermatoses with varying and overlapping clinical presentations. Physicians should be aware of the growing list of associated diseases in order to build a better differential diagnosis or to potentially investigate for co-existing disease.

Pyoderma gangraenosum als diagnostische und therapeutische interdisziplinäre Herausforderung

Das Pyoderma gangraenosum (PG) ist eine neutrophile Dermatose unklarer Genese, die sowohl in Assoziation zu hämatologischen und neoplastischen Systemerkrankungen, chronisch-entzündlichen Darmerkrankungen und autoinflammatorischen Syndromen als auch idiopathisch auftreten kann. Sowohl die Diagnosestellung wie auch die Therapie des PG stellen aufgrund seiner Seltenheit, des Fehlens großer randomisierter kontrollierter Studien und der unzureichend verstandenen Pathogenese eine Herausforderung in der klinischen Praxis dar. Diese Übersichtsarbeit beschreibt und diskutiert aktuelle Erkenntnisse, die das PG als autoinflammatorische Erkrankung beschreiben. Durch eine Dysregulation von T-Lymphozyten und myeloiden Zellen wie den neutrophilen Granulozyten kommt es zur Entstehung von Pusteln und großflächigen Ulzera. Klassische Therapieansätze umfassen eine anti-inflammatorische topische Therapie, eine Analgesie sowie die systemische Gabe von Immunmodulantien oder -suppressiva. Neuere, bisher nicht zugelassene Therapieoptionen sind der Einsatz von Biologika und JAK-Inhibitoren.

Epidermotropie von Immunzellen unterscheidet Pyoderma gangraenosum vom Ulcus cruris venosum

HINTERGRUND UND ZIELE

Pyoderma gangraenosum ist eine ulzerierende, autoinflammatorische Erkrankung. Es gibt keine eindeutigen histopathologischen Merkmale zur Differenzierung von anderen Ursachen chronischer Wunden wie dem Ulcus cruris venosum. Ziel dieser Studie war es, histopathologische Merkmale von Pyoderma gangraenosum und Unterschiede zu venösen Ulzerationen zu detektieren.

PATIENTEN UND METHODIK

Acht Gewebeproben von Pyoderma gangraenosum, zwölf Proben von Ulcus cruris venosum und sechs Proben von gesunder Haut wurden einer immunhistologischen Multi-Antigen-Analyse unterzogen. Das Immuninfiltrat und seine räumliche Verteilung wurden anhand von Fluoreszenzbildern mit einer Gewebezytometriesoftware analysiert.

ERGEBNISSE

Die dichte epidermale Präsenz von CD45RO⁺ -T-Gedächtnis-Zellen und die Rarefizierung von CD1a⁺ -Langerhans-Zellen in der Epidermis waren Marker für Pyoderma gangraenosum, welche auch auf eine epidermale Immunreaktion schließen lassen. Darüber hinaus konnte dermal eine hohe Anzahl CD11c⁺ CD68⁺ pro-inflammatorischer M1-Makrophagen nachgewiesen werden. Diese überstieg die Anzahl der in venösen Ulzerationen beobachteten Makrophagen deutlich.

SCHLUSSFOLGERUNGEN

Die histopathologischen Unterschiede zwischen Pyoderma gangraenosum und Ulcus cruris venosum können zur Unterscheidung der beiden Erkrankungen herangezogen werden und somit eine wichtige Hilfe zur schnellen Einleitung einer adäquaten Therapie sein. Darüber hinaus deuten unsere Daten auf einen antigengesteuerten Prozess in der Epidermis hin, möglicherweise unter Beteiligung von CD1a⁺ Langerhans-Zellen.

Epidermotropism of inflammatory cells differentiates pyoderma gangrenosum from venous leg ulcers

BACKGROUND AND OBJECTIVES

Pyoderma gangrenosum is an ulcerative autoinflammatory disease, lacking distinct histopathological characteristics to differentiate from other ulcerating conditions, like venous leg ulcers. The objective of this study was therefore to find histopathological characteristics of pyoderma gangrenosum in a head-to-head comparison to venous leg ulcers.

PATIENTS AND METHODS

Eight tissue samples of pyoderma gangrenosum, twelve samples of venous leg ulcers and six samples of healthy skin were stained using an immunohistological multi antigen staining technology. The immune infiltrate and its spatial distribution were analyzed with contextual tissue cytometry software using fluorescence images.

RESULTS

The dense epidermal presence of CD45RO⁺ memory T cells and the rarefication of CD1a⁺ Langerhans cells in the epidermis were defining markers for pyoderma gangrenosum, implicating an epidermal immune reaction. In addition, high numbers of CD11c⁺ CD68⁺ pro-inflammatory M1 macrophages were detected in the dermis, significantly extending the numbers seen in venous leg ulcers.

CONCLUSIONS

The histopathological differences found between pyoderma gangrenosum and venous leg ulcer can be used to distinguish between the two diseases and thus provide an important aid for the rapid initiation of adequate therapy. In addition, our data hint at an antigen-driven process in the epidermis, possibly involving CD1a⁺ Langerhans cells.

Neutrophilic Dermatoses: a Clinical Update

Purpose of Review

Neutrophilic dermatoses are defined by the presence of a sterile neutrophilic infiltrate on histopathology. This review focuses on the pathogenesis, epidemiology, clinicopathological features, diagnosis, and management of four disorders: Sweet syndrome, pyoderma gangrenosum, Behçet syndrome, and neutrophilic eccrine hidradenitis.

Recent Findings

Recent studies have provided insight into the complex pathogenesis of neutrophilic dermatoses. Evidence supports an intricate interplay of abnormal neutrophil function and inflammasome activation, malignant transformation into dermal infiltrating neutrophils, and genetic predisposition.

Summary

Neutrophilic dermatoses have diverse cutaneous and extracutaneous manifestations and may be associated with significant morbidity and mortality. Common underlying associations include infectious, inflammatory, and neoplastic disorders, as well as drug reactions. Emerging diagnostic and therapeutic frameworks identify an expanding role for biologic and targeted anti-inflammatory therapies.

Efficacy of cytapheresis for induction therapy and extra-intestinal skin manifestations of ulcerative colitis

INTRODUCTION

In recent years, the prevalence of inflammatory bowel diseases has been increasing in Japan due to the westernization of lifestyles. Many patients have been reported to have extra-intestinal manifestations (EIMs) at least once. Skin lesions occur with a high degree of frequency among EIMs, with erythema nodosum (EN) and pyoderma gangrenosum (PG) the main complications. Cytapheresis is again attracting attention as a treatment with few side effects.

METHODS

We investigated the therapeutic effect of cytapheresis on ulcerative colitis (UC) and cutaneous EIMs. Between 2008 and 2021, 240 patients with active UC had induction therapy by cytapheresis at our hospital.

RESULTS

Remission and response rates were 50.0% and 67.5%, respectively. Apheresis was performed on 7 patients with PG and 5 patients with EN with a good response. Serious adverse events were not observed.

CONCLUSION

This retrospective assessment of efficacy showed that EN and PG responded favorably to cytapheresis. This article is protected by copyright. All rights reserved.

Pyoderma Gangrenosum: A Systematic Review of the Molecular Characteristics of Disease

Pyoderma Gangrenosum is a painful recurrent ulcerative neutrophilic dermatosis in which the pathogenesis is incompletely defined. Current evidence suggests that PG is associated with dysregulation of components of both the innate and adaptive immune system with dysregulation of neutrophil function and contribution of the Th17 immune axis. PG can present in numerous heterogeneous clinical presentations and be associated with multiple inflammatory conditions including Rheumatoid Arthritis, inflammatory bowel disease and hidradenitis suppurativa. However, no critical evaluation of the observed molecular characteristics in PG studies in association with their clinical findings has been assessed. Additionally, emerging evidence suggests a potential role for other cell types and immune pathways including B cells, macrophages, autoantibodies, and the complement system in PG although these have not yet been integrated into the pathogenesis of disease. This systematic review aims to critically evaluate the current molecular observations regarding the pathogenesis of PG and discuss associations with clinical characteristics as well as the evidence supporting novel cell types and immune pathways in PG.

Dealing with Corticosteroid and High-Dose Cyclosporine Therapy in a Pyoderma Gangrenosum Patient Contracting a COVID-19 Infection

Pyoderma gangrenosum (PG) is a rare and chronic neutrophil inflammation belonging to the spectrum of autoinflammatory disorders. Immunosuppressive therapy is the cornerstone of successful treatment. However, due to the global COVID-19 pandemic, physicians struggle with therapeutic strategies during infection. This paper describes the case of a 58-year-old patient with a very painful, rapidly increasing wound on his right foot, which was diagnosed as pyoderma gangrenosum. Five weeks after the initial treatment with high-dose immunosuppressives (combination therapy with cyclosporine A and systemic methylprednisolone), he became infected with COVID-19. Reduction in the immunosuppressive dosage proved effective, as the patient recovered from COVID-19 without any complication and showed rapid wound healing.

Acne Syndromes and Mosaicism

Abnormal mosaicism is the coexistence of cells with at least two genotypes, by the time of birth, in an individual derived from a single zygote, which leads to a disease phenotype. Somatic mosaicism can be further categorized into segmental mosaicism and nonsegmental somatic mosaicism. Acne is a chronic illness characterized by inflammatory changes around and in the pilosebaceous units, commonly due to hormone- and inflammatory signaling-mediated factors. Several systemic disorders, such as congenital adrenal hyperplasia, polycystic ovarian syndrome, and seborrhoea-acne-hirsutism-androgenetic alopecia syndrome have classically been associated with acne. Autoinflammatory syndromes, including PAPA, PASH, PAPASH, PsAPASH, PsaPSASH, PASS, and SAPHO syndromes include acneiform lesions as a key manifestation. Mosaic germline mutations in the FGFR2 gene have been associated with Apert syndrome and nevus comedonicus, two illnesses that are accompanied by acneiform lesions. In this review, we summarize the concept of cutaneous mosaicism and elaborate on acne syndromes, as well as acneiform mosaicism.

Adult-onset immunodeficiency due to anti-interferon-gamma autoantibody-associated Sweet syndrome: A distinctive entity

Sweet syndrome (SS) has been increasingly reported in patients with adult-onset immunodeficiency (AOID) due to anti-interferon-γ autoantibody who also have concomitant opportunistic infections, especially disseminated non-tuberculous mycobacterial infection (dNTMI). A retrospective study retrieving data from 2011 through 2020 was conducted. We compared clinical characteristics of SS with and without AOID and generated the prediction model and examined the interaction between AOID and dNTMI in the occurrence of SS. Lymphadenopathy, pustular lesions, and leukocytosis are the significant predictors for AOID-associated SS. Adjusted risk differences were 0.58 (95% confidence interval [CI], 0.33-0.83), 0.21 (95% CI, 0.02-0.39), and 0.24 (95% CI, 0.01-0.47), respectively. Based on the analysis of aggregated cross-sectional data, both the overall and the direct effect of AOID increased the prevalence of SS. The indirect effect of AOID on the occurrence of SS might also be mediated through dNTMI or other common opportunistic infections. In addition, there was a trend of positive additive interaction between AOID and dNTMI. Although the test of additive interaction did not reveal statistically significant results, a deviation from additivity of isolated effects might suggest potential causal interaction between AOID and dNTMI. The distinctive clinical syndrome comprising lymphadenopathy, pustular lesions, and leukocytosis in patients with SS should raise the awareness of clinicians to the potential of underlying AOID.

Pyoderma Gangrenosum: A Rare Disease With Dire Consequences in Facial Aesthetic Surgery Patients

Pyoderma gangrenosum (PG) is a rare, inflammatory dermatologic condition characterized by painful cutaneous ulcerations. Herein, we describe the third documented case of PG arising in an elective plastic surgery patient who had undergone an otherwise uncomplicated facelift. We describe the course of her diagnosis and management of PG, which involved her face and neck and then progressed to her lower extremities. Although the etiology remains unknown, PG often arises in a host with another autoimmune disease. In the case described, the patient was diagnosed with an immunoglobulin A gammopathy shortly after she developed PG. Following the case report, the pathogenesis, diagnosis, and treatment strategy of PG is briefly reviewed. Level of Evidence: 5.

Inflammatory arthritis-associated pyoderma gangrenosum: a systematic review

INTRODUCTION/OBJECTIVES

Pyoderma gangrenosum (PG) is a rare, rapidly progressive neutrophilic dermatosis commonly associated with systemic inflammatory diseases. We aimed to characterize the association of PG and inflammatory arthritis, as little is known outside of case reports and small cohort studies.

METHOD

We performed a systematic review in PubMed, EMBASE, and Scopus from inception to present using the terms arthritis and pyoderma gangrenosum. Patient demographics, clinical presentation, and treatment outcomes were recorded. Descriptive statistics and stratified analysis were used to compare factors of interest by type of arthritis.

RESULTS

A total of 1399 articles were screened, and 129 patients with inflammatory arthritis and PG were included in the review. The most common types of arthritis were rheumatoid arthritis (RA) (50.4%), inflammatory bowel disease (IBD)-associated arthritis (10.9%), and psoriatic arthritis (8.5%). In the vast majority of cases, joint symptoms preceded PG, by a median of 10 years (inter-quartile range [IQR] 5-16). Corticosteroid monotherapy and biologic therapies, used alone or in combination, resulted in improvement or complete resolution of ulcers 71.4% and 67.3% of the time, respectively. Within the latter, infliximab, adalimumab, and anakinra were most successful in inducing remission overall. RA and non-RA did not differ significantly in treatment success or healing time.

CONCLUSIONS

This study shows that PG is frequently preceded by inflammatory arthritis, most commonly RA. Clinicians used a wide variety of treatment regimens with variable outcomes. While larger studies are needed to standardize the treatment of inflammatory arthritis-associated PG, this study suggests that in addition to systemic corticosteroids, biologic medications can be effective treatment options for these patients.

KEY POINTS

• Inflammatory arthritis, most commonly rheumatoid arthritis, often precedes rather than follows pyoderma gangrenosum. • Other forms of arthritis associated with PG included IBD-associated arthritis and psoriatic arthritis. • Biologic therapies, such as infliximab, adalimumab, and anakinra, were largely successful in treating arthritis-associated pyoderma gangrenosum and may play an important role in corticosteroid-sparing therapy or in a maintenance regimen for this subset of patients. • The type of inflammatory arthritis associated with pyoderma gangrenosum may not be a helpful treatment guide as it was not significantly associated with treatment outcomes or healing time.

Estimating the Odds of Ulcerative Colitis-Associated Pyoderma Gangrenosum: A Population-Based Case-Control Study

BACKGROUND

Ulcerative colitis (UC) is a well-known underlying comorbidity of pyoderma gangrenosum (PG). However, the risk conferred by UC for the subsequent development of PG is yet to be elucidated. We aimed to estimate the magnitude of the association between UC and the subsequent occurrence of PG, which would enable us to assess the odds of PG developing in individuals with a history of UC.

METHODS

A population-based case-control study was conducted to compare PG patients (n = 302) and age-, sex- and ethnicity-matched control subjects (n = 1,497) regarding the presence of UC. Logistic regression models were utilized for univariate and multivariate analyses.

RESULTS

The prevalence of preexisting UC was greater in patients with PG than in controls (7.3 vs. 0.5%; p < 0.001). A 15-fold increase in the odds of PG in individuals with preexisting UC was observed (OR 14.62, 95% CI 6.45-33.18). The greatest risk of developing PG occurred in the first years following the diagnosis of UC (OR 35.50, 95% CI 4.35-289.60), and decreased thereafter to 10.03 (95% CI 1.83-55.03), 6.69 (95% CI 1.49-30.02), and 10.03 (95% CI 1.83-55.03) at 1-5, 5-10, and 10-15 years after the diagnosis of UC, respectively. This association retained its statistical significance following the adjustment for confounding factors (adjusted OR 10.78, 95% CI 4.55-25.52). Patients with both PG and UC were younger and had a lower prevalence of smoking than the remaining patients with PG.

CONCLUSIONS

UC increases the odds of developing PG by 15-fold, with the highest probability of developing PG occurring within the first year after the diagnosis of UC. Patients with UC may be advised to avoid additional precipitating factors for the development of PG.

Simultaneous occurrence of Pyoderma Gangrenosum and Palmoplantar Pustular Psoriasis: Is it an association or coincidental findings?

Pyoderma Gangrenosum and Palmoplantar Pustular Psoriasis share the common pathogenesis, histological features, age group, and female preponderance that suggests a common etiological link.

Immune-Mediated Dermatoses in Patients with Haematological Malignancies: A Comprehensive Review

Haematological malignancies induce important alterations of the immune system, which account for the high frequency of autoimmune complications observed in patients. Cutaneous immune-mediated diseases associated with haematological malignancies encompass a heterogeneous group of dermatoses, including, among others, neutrophilic and eosinophilic dermatoses, autoantibody-mediated skin diseases, vasculitis and granulomatous dermatoses. Some of these diseases, such as paraneoplastic pemphigus, are associated with an increased risk of death; others, such as eosinophilic dermatoses of haematological malignancies, run a benign clinical course but portend a significant negative impairment on a patient’s quality of life. In rare cases, the skin eruption reflects immunological alterations associated with an unfavourable prognosis of the associated haematological disorder. Therapeutic management of immune-mediated skin diseases in patients with haematological malignancies is often challenging. Systemic corticosteroids and immunosuppressive drugs are considered frontline therapies but may considerably augment the risk of serious infections. Indeed, developing a specific targeted therapeutic approach is of crucial importance for this particularly fragile patient population. This review provides an up-to-date overview on the immune-mediated skin diseases most frequently encountered by patients with onco-haematological disorders, discussing new pathogenic advances and therapeutic options on the horizon.

[Targeted therapies in Pyoderma gangrenosum: deciphering pathophysiology and improving disease management]

The immune response is a central process during wound healing. Malfunctions often lead to chronic inflammation, barrier disorders, and ulcerations of the skin. The underlying pathomechanisms are complex and the subject of current dermatological research. The care of wound healing disorders is still inadequate and urgently needs improved therapy concepts. For several years now, the development of modern immunomodulators has enabled the targeted regulation of specific signaling cascades, and their effectiveness in the treatment of wound healing disorders has been proven in numerous case studies. Thus, their use not only leads to more efficient therapeutic approaches, but also provides deeper insight into the pathomechanistic importance of specific signaling pathways in inflammatory and degenerative diseases of the skin, which are poorly understood so far. Pyoderma gangrenosum, an autoinflammatory disease, provides a good example to illustrate the progress in therapy and pathomechanistic understanding through the use of new immunomodulators and is explained in more detail in the following article.

Pyoderma gangrenosum

Pyoderma gangrenosum (PG) is a rare neutrophilic dermatosis that presents with rapidly developing, painful skin ulcers hallmarked by undermined borders and peripheral erythema. Epidemiological studies indicate that the average age of PG onset is in the mid-40s, with an incidence of a few cases per million person-years. PG is often associated with a variety of other immune-mediated diseases, most commonly inflammatory bowel disease and rheumatoid arthritis. The cause of PG is not well understood, but PG is generally considered an autoinflammatory disorder. Studies have focused on the role of T cells, especially at the wound margin; these cells may support the destructive autoinflammatory response by the innate immune system. PG is difficult to diagnose as several differential diagnoses are possible; in addition to clinical examination, laboratory tests of biopsied wound tissue are required for an accurate diagnosis, and new validated diagnostic criteria will facilitate the process. Treatment of PG typically starts with fast-acting immunosuppressive drugs (corticosteroids and/or cyclosporine) to reduce inflammation followed by the addition of more slowly acting immunosuppressive drugs with superior adverse event profiles, including biologics (in particular, anti-tumour necrosis factor (TNF) agents). Appropriate wound care is also essential. Future research should focus on PG-specific outcome measures and PG quality-of-life studies.

Postsurgical pyoderma gangrenosum and flap necrosis in a head and neck cancer patient following neck dissection

Postsurgical pyoderma gangrenosum (PSPG) develops in the skin after surgery without known cause. Immunosuppression constitutes first-line therapy and increases the likelihood of successful surgery when needed. PSPG should be considered when a flap necrosis occurs.

Pyoderma gangrenosum: From historical perspectives to emerging investigations

Pyoderma gangrenosum (PG) is a rare disease of unknown aetiology, first described over a century ago. Initially thought to have an infectious cause, and now primarily considered an autoinflammatory condition, PG continues to be poorly understood, commonly misdiagnosed, and difficult to treat. In this review, we discuss the journey of our understanding of PG to date, including first descriptions, challenges with diagnosis, presumed pathogenesis, and treatments used. We highlight major historical landmarks and their importance, explain the rationale behind current investigations, note outstanding gaps in knowledge, and explore the future directions of PG research. We summarise what we have known, what we are working on knowing, and what we have yet to explore about PG, illustrating overall trends to invigorate future research.

[Neutrophilic and pustular dermatoses : New autoinflammatory diseases and syndromes]

This article reviews noninfectious inflammatory dermatoses with mainly neutrophilic infiltrates and the formation of pustules. The infiltrate containing neutrophils may either be mild as in urticaria or very dense, even with leukocytoclasia, as in Sweet syndrome or pyoderma gangrenosum. Neutrophilic infiltrates and pustular eruptions are caused by different noninfectious immunomechanisms. For some of them, mutations have been found (e.g. NLRC4 mutation in cryopyrin-associated periodic syndromes (CAPS) leading to activation of the inflammasome; IL36RN mutation in pustular psoriasis resulting in uncontrolled IL36 signaling). Neutrophilic dermatoses are of high interest, as they may be the cause of underlying benign or malignant conditions. In recent years, efficient targeted therapies have been developed.

Thalidomide in the Treatment of Sweet's Syndrome and Eosinophilic Folliculitis Associated With Immune Reconstitution Inflammatory Syndrome

Sweet's syndrome and eosinophilic folliculitis are aseptic inflammatory dermatitis mainly because of infiltrated neutrophils and eosinophils on skin, respectively. These diseases rarely overlap or coexist in the same patient, especially co-occur in HIV infected patient. Here, we report a rare case of an AIDS patient who developed eosinophilic folliculitis and Sweet's syndrome within 1 month of initial antiretroviral therapy, presumably due to immune reconstitution inflammatory syndrome. The CD4⁺ T cell counts increased dramatically from 70 to 249 cells/μL within a period of 1 month. Interestingly, the patient was rapidly and strikingly responsive to thalidomide, which has anti-inflammatory, immune regulation, inhibition of neutrophil chemotaxis etc. Moreover, we focused our attention on discussing the clinical, pathological, and possible pathogenic aspects of the rare overlap of HIV complicated with neutrophilic and eosinophilic dermatosis.

[Pyoderma gangrenosum and systemic lupus erythematosus: A rare association]

INTRODUCTION

Pyoderma gangrenosum (PG) is a neutrophilic dermatosis that is traditionally associated with systemic disorders such as chronic inflammatory bowel diseases, rheumatoid arthritis and malignant hematologic disorders. Its association with systemic lupus erythematosus (SLE) is rare and not well known. We report a case of this association with a review of the literature.

CASE REPORT

A 43-year-old female patient, followed for 4 years for SLE, presented a deep ulceration of the anterior face of the left thigh with inflammatory borders, an ulcerated nodule of the right shoulder and four small ulcerations of the back of the right hand. The biopsy of the ulceration of the left thigh concluded to PG. The patient was treated by corticosteroids with complete healing of lesions.

CONCLUSION

The prognosis of lupus does not seem to be aggravated by PG and the treatments of a SLE flare are usually enough for treating associated PG.

Mechanisms of Inflammation in Neutrophil-Mediated Skin Diseases

Neutrophil-mediated skin diseases, originally named neutrophilic dermatoses (NDs), are a group of conditions due to an altered neutrophil recruitment and activation, characterized by polymorphic cutaneous manifestations with possible internal organ involvement. Although a number of diseases are included in this setting, the two prototypic forms are pyoderma gangrenosum (PG) and Sweet's syndrome (SS) which usually present with skin ulcers and plaque-type lesions, respectively. They have central features significantly overlapping with autoinflammatory conditions which manifest as repeated episodes of tissue inflammation. However, in contrast to appropriate inflammatory responses to insults or to autoimmune disease, there is an absence of identifiable pathogens, autoantibodies, or autoreactive lymphocytes. The recognition of monogenic autoinflammatory diseases which can present with NDs has led to study several genes involved in autoinflammation in NDs. Based on discovering of a number of mutations involving different autoinflammatory genes, neutrophil-mediated skin diseases are nowadays regarded as a spectrum of polygenic autoinflammatory conditions. Although disease mechanisms have not yet been completely elucidated, NDs are recognized as diseases involving dysfunctional cellular signaling mediated by pathways mainly related to inflammasome and IL-1 with the contributory role of IL-17 and other effector molecules. The precise elucidation of the above-mentioned pathologic mechanisms may pave the way to tailored treatments for patients with different neutrophil-mediated skin diseases.