Pyogenic arthritis, pyoderma gangrenosum, and acne syndrome maps to chromosome 15q

The Pathophysiology and Treatment of Pyoderma Gangrenosum-Current Options and New Perspectives

Pyoderma gangrenosum (PG) is an uncommon inflammatory dermatological disorder characterized by painful ulcers that quickly spread peripherally. The pathophysiology of PG is not fully understood; however, it is most commonly considered a disease in the spectrum of neutrophilic dermatoses. The treatment of PG remains challenging due to the lack of generally accepted therapeutic guidelines. Existing therapeutic methods focus on limiting inflammation through the use of immunosuppressive and immunomodulatory therapies. Recently, several reports have indicated the successful use of biologic drugs and small molecules administered for coexisting diseases, resulting in ulcer healing. In this review, we summarize the discoveries regarding the pathophysiology of PG and present treatment options to raise awareness and improve the management of this rare entity.

Chronic Non-bacterial Osteomyelitis (CNO) In Childhood: A Review

Chronic non-bacterial osteomyelitis (CNO) is an autoinflammatory bone disorder mostly affecting children and adolescents. Although it is considered a rare disease, CNO is likely to be the single most common autoinflammatory bone disease in childhood, underdiagnosed and underreported due to a lack of awareness of the condition in both medics and patients and the absence of validated diagnostic criteria. The exact underlying pathogenesis of CNO remains unknown, making targeted treatment difficult. This issue is exacerbated by the lack of any randomised control trials, meaning that treatment strategies are based solely on retrospective reviews and case series. This review summarises the current concepts in pathophysiology, the clinical features that help differentiate important differential diagnoses, and an approach to investigating and managing children with CNO. Ultimately, the timely and thorough investigation of children and young people with CNO is vitally important to exclude important mimics and initiate appropriate management that can prevent the complications of persistent inflammatory bone disease.

Pediatric autoinflammatory bone disorders-a mini review with special focus on pathogenesis and inborn errors of immunity

Autoinflammatory bone disorders are a group of diseases characterized by sterile osteomyelitis. This includes chronic nonbacterial osteomyelitis and the monogenic forms, Majeed syndrome and deficiency of the interleukin-1 receptor antagonist. These disorders result from innate immune system dysregulation and cytokine imbalance that triggers inflammasome activation causing downstream osteoclastogenesis and excessive bone remodeling. In this review, we will summarize the immunopathogenesis of pediatric autoinflammatory bone diseases with a special focus on the genetics and inborn errors of immunity, while briefly touching on the clinical manifestations and management of each disease as well as areas for future research.

Rare Case of Pyoderma Gangrenosum in the Setting of PAPA Syndrome in a 12-Year-Old Child

We report on a 12-year-old boy who presented with an intermittently painful wound present for months without any tendency to heal after a slackline accident two years ago. A biopsy of the ulcer margin revealed epithelial hyperplasia, marked fibrosis, and vascular proliferation without evidence of vasculitis. Pretibial findings on the right side were a 3.8 ×  3.1 cm fibrin-covered, flat ulcer with slight reddening of the surrounding area. Other findings were unremarkable with hypermobility of the wrists and finger joints. Local therapy with a foam dressing, topical steroid in the wound margin, and class II compression stockings showed no effect. The pediatric rheumatologist evaluated the ulcer with a camptodactyly of digit 5, subluxation of the wrists on both sides, and symmetric ulnar deviation. Elevated S100 as an isolated autoimmune phenomenon or concomitant with systemic autoimmune disease or autoinflammation (eg, Pyogenic sterile arthritis, pyoderma gangrenosum, and acne syndrome) was also observed. The therapy with oral steroids, initially 30 mg/day and gradual reduction in the course, only achieved a tissue bridge's formation with the same size extension of the ulcer. Unfortunately, the patient spontaneously developed a second ulcer on the left lateral malleolus, which is why the therapy was changed to dapsone 50 mg/day and tacrolimus in the wound margin after nine weeks. In the absence of success, further treatment with ciclosporin or tumor necrosis factor-alpha antibody therapy is planned in interdisciplinary cooperation.

Pyogenic arthritis, pyoderma gangrenosum, and acne syndrome in a Chinese family: A case report and review of literature

BACKGROUND

Pyogenic arthritis, pyoderma gangrenosum, and acne (PAPA) syndrome is a rare autosomal dominant genetic disease characterized by severe autoimmune inflammation, caused by mutations in the PSTPIP1 gene. Due to PAPA heterogeneous clinical manifestation, misdiagnosis or delayed diagnoses are difficult to avoid. With the use of whole-exome sequencing, we identified a missense mutation in the PSTPIP1 gene in a Chinese family. To the best of our knowledge, this is the first case of PAPA reported in China.

CASE SUMMARY

A 9-year-old boy suffered from recurrent aseptic pyogenic arthritis triggered by minor trauma or few obvious predisposing causes for more than 3 years. Pyogenic arthritis occurred every 3-5 mo, affecting his knees, elbows, and ankle joints. Treatments, such as glucocorticoids, antibiotics, even surgeries could alleviate joints pain and swelling to some extent but could not inhibit the recurrence of arthritis. Similar symptoms were present in his younger brother but not in his parents. According to the whole-exome sequencing, a missense mutation in exon 11 of the PSTPIP1 gene (c.748G>C; p.E250Q) was detected in the boy, his younger brother and his father. Taking into account the similar phenotypic features with PAPA syndrome reported previously, we confirmed a diagnosis of PAPA syndrome for the family.

CONCLUSION

In this case, a missense mutation (c.748G>C; p.E250Q) in PSTPIP1 gene was identified in a Chinese family with PAPA syndrome. Previous studies emphasize the fact that PAPA syndrome is hard to diagnose just through the clinical manifestations owing to its heterogeneous expression. Genetic testing is an effectual auxiliary diagnostic method, especially in the early stages of pyogenic arthritis. Only if we have a deep understanding and rich experience of this rare disease can we make a prompt diagnosis, develop the best clinical treatment plan, and give good fertility guidance.

The combined prevalence of classified rare rheumatic diseases is almost double that of ankylosing spondylitis

BACKGROUND

Rare diseases (RDs) affect less than 5/10,000 people in Europe and fewer than 200,000 individuals in the United States. In rheumatology, RDs are heterogeneous and lack systemic classification. Clinical courses involve a variety of diverse symptoms, and patients may be misdiagnosed and not receive appropriate treatment. The objective of this study was to identify and classify some of the most important RDs in rheumatology. We also attempted to determine their combined prevalence to more precisely define this area of rheumatology and increase awareness of RDs in healthcare systems. We conducted a comprehensive literature search and analyzed each disease for the specified criteria, such as clinical symptoms, treatment regimens, prognoses, and point prevalences. If no epidemiological data were available, we estimated the prevalence as 1/1,000,000. The total point prevalence for all RDs in rheumatology was estimated as the sum of the individually determined prevalences.

RESULTS

A total of 76 syndromes and diseases were identified, including vasculitis/vasculopathy (n = 15), arthritis/arthropathy (n = 11), autoinflammatory syndromes (n = 11), myositis (n = 9), bone disorders (n = 11), connective tissue diseases (n = 8), overgrowth syndromes (n = 3), and others (n = 8). Out of the 76 diseases, 61 (80%) are classified as chronic, with a remitting-relapsing course in 27 cases (35%) upon adequate treatment. Another 34 (45%) diseases were predominantly progressive and difficult to control. Corticosteroids are a therapeutic option in 49 (64%) syndromes. Mortality is variable and could not be determined precisely. Epidemiological studies and prevalence data were available for 33 syndromes and diseases. For an additional eight diseases, only incidence data were accessible. The summed prevalence of all RDs was 28.8/10,000.

CONCLUSIONS

RDs in rheumatology are frequently chronic, progressive, and present variable symptoms. Treatment options are often restricted to corticosteroids, presumably because of the scarcity of randomized controlled trials. The estimated combined prevalence is significant and almost double that of ankylosing spondylitis (18/10,000). Thus, healthcare systems should assign RDs similar importance as any other common disease in rheumatology.

Pyoderma gangrenosum confined to the irradiated chest wall of the reconstructed breast

Pyoderma gangrenosum (PG) is a diagnosis of exclusion worsened by surgical debridement. This report presents two atypical manifestations of PG in the reconstructed breast, whereby the disease is only confined to the irradiated chest wall tissue bed, sparing the abdominal donor sites and the contralateral reconstructed breast.

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.

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.

Monogenic autoinflammatory diseases in children: single center experience with clinical, genetic, and imaging review

Purpose

1. To review the contemporary literature and present a list of the imaging findings for patients with autoinflammatory diseases from our hospital. All these patients are found to have a genetic mutation that is responsible for their disease.

2. To present follow-up imaging findings, when available, and correlate those with symptoms and type of treatment administered in approximately 40 patients with autoinflammatory diseases of a single tertiary pediatric health care center including familial Mediterranean fever, Cryopyrin-associated autoinflammatory syndrome, PAPA (pyogenic arthritis, pyoderma gangrenousum, and acne) syndrome, and more. These findings are related to disease progression, treatment response, or treatment-induced changes.

Conclusion

Autoinflammatory diseases are relatively rare entities that can affect any system of the body. Given the many nonspecific imaging features, awareness of these diseases and good communication with clinicians aid in reaching an accurate diagnosis.

Moving towards a systems-based classification of innate immune-mediated diseases

Autoinflammation as a distinct disease category was first reported in 1999 as a group of monogenic disorders characterized by recurrent episodes of systemic and organ-specific inflammation, known as periodic fever syndromes. Since this original description, the focus has shifted considerably to the inclusion of complex multifactorial conditions with an autoinflammatory basis. Furthermore, the boundaries of what are considered to be autoinflammatory disorders are constantly evolving and currently encompass elements of immunodeficiency and autoimmunity. Notable developments in the intervening 20 years include substantial progress in understanding how the different inflammasomes are activated, how infection is sensed by the innate immune system and how intracellular signalling systems are consequently activated and integrated with many different cellular functions in the autoinflammatory process. With these developments, the field of autoinflammation is moving from a gene-centric view of innate immune-mediated disease towards a systems-based concept, which describes how various convergent pathways, including pyrin and the actin cytoskeleton, protein misfolding and cellular stress, NF-κB dysregulation and interferon activation, contribute to the autoinflammatory process. The development and adoption of a systems-based concept of systemic autoinflammatory diseases is anticipated to have implications for the development of treatments that target specific components of the innate immune system.

Prevalence estimates for pyoderma gangrenosum in the United States: An age- and sex-adjusted population analysis

BACKGROUND

The disease burden of pyoderma gangrenosum (PG) is poorly understood.

OBJECTIVE

To determine standardized overall and age-, sex-, and race-specific prevalence estimates for PG among adults in the United States.

METHODS

Cross-sectional analysis of 1971 patients with PG identified using electronic health records data from a diverse population-based sample of more than 58 million patients.

RESULTS

The age- and sex-standardized prevalence of PG among the study population was 0.0058%, or 5.8 PG cases (95% confidence interval [CI], 5.6-6.1) per 100,000 adults. Adjusted prevalence was nearly twice as high among women (7.1 cases [95% CI, 6.7-7.5] per 100,000) than men (4.4 cases [95% CI, 4.0-4.7] per 100,000). Patients between the ages of 70 and 79 years had the highest standardized prevalence (9.8 cases [95% CI, 8.8-10.9] per 100,000), with patients aged ≥50 years representing nearly 70% of all PG cases. Standardized prevalence was similar among white and African American patients. The female-to-male ratio of PG was >1.8 across all age groups.

LIMITATIONS

Analysis of electronic health records data may result in misclassification bias.

CONCLUSION

PG is a rare disease that most commonly affects women and those aged ≥50 years.

Inflammasome-Dependent Cytokines at the Crossroads of Health and Autoinflammatory Disease

As key regulators of both innate and adaptive immunity, it is unsurprising that the activity of interleukin (IL)-1 cytokine family members is tightly controlled by decoy receptors, antagonists, and a variety of other mechanisms. Additionally, inflammasome-mediated proteolytic maturation is a prominent and distinguishing feature of two important members of this cytokine family, IL-1β and IL-18, because their full-length gene products are biologically inert. Although vital in antimicrobial host defense, deregulated inflammasome signaling is linked with a growing number of autoimmune and autoinflammatory diseases. Here, we focus on introducing the diverse inflammasome types and discussing their causal roles in periodic fever syndromes. Therapies targeting IL-1 or IL-18 show great efficacy in some of these autoinflammatory diseases, although further understanding of the molecular mechanisms leading to unregulated production of these key cytokines is required to benefit more patients.

Imaging findings of sterile pyogenic arthritis, pyoderma gangrenosum and acne (PAPA) syndrome: differential diagnosis and review of the literature

Pyogenic arthritis, pyoderma gangrenosum and acne (PAPA) syndrome is a rare autosomal-dominant autoinflammatory disease of incomplete penetrance and variable expression. PAPA syndrome is the result of a mutation in the proline serine threonine phosphatase-interacting protein 1 (PSTPIP1/CD2BP1) gene located on chromosome 15, which results in an abnormal overproduction of the pro-inflammatory cytokine interleukin-1β (IL-1). This syndrome clinically manifests as early onset of recurrent episodes of acute aseptic inflammation of the joints, generally occurring in the first two decades of life, followed by manifestation of characteristic skin lesions in the third decade, after an obvious decline in the joint symptoms. Although uncommon, the potential clinical implications of PAPA syndrome warrant an appropriate diagnosis in a timely fashion.

Neutrophilic dermatoses: Pathogenesis, Sweet syndrome, neutrophilic eccrine hidradenitis, and Behçet disease

Neutrophilic dermatoses are a heterogeneous group of inflammatory skin disorders that present with unique clinical features but are unified by the presence of a sterile, predominantly neutrophilic infiltrate on histopathology. The morphology of cutaneous lesions associated with these disorders is heterogeneous, which renders diagnosis challenging. Moreover, a thorough evaluation is required to exclude diseases that mimic these disorders and to diagnose potential associated infectious, inflammatory, and neoplastic processes. While some neutrophilic dermatoses may resolve spontaneously, most require treatment to achieve remission. Delays in diagnosis and treatment can lead to significant patient morbidity and even mortality. Therapeutic modalities range from systemic corticosteroids to novel biologic agents, and the treatment literature is rapidly expanding. The first article in this continuing medical education series explores the pathogenesis of neutrophilic dermatoses and reviews the epidemiology, clinical and histopathologic features, diagnosis, and management of Sweet syndrome, neutrophilic eccrine hidradenitis, and Behçet disease.

Genetic architecture of acne vulgaris

Acne vulgaris is a ubiquitary skin disease characterized by chronic inflammation of the pilosebaceous unit resulting from bacterial colonization of hair follicles by Propionibacterium acnes, androgen-induced increased sebum production, altered keratinization and inflammation. Here, we review our current understanding of the genetic architecture of this intriguing disease. We analysed genomewide association studies (GWAS) and candidate genes studies for acne vulgaris. Moreover, we included GWAS studies for the associated disease polycystic ovary syndrome (PCOS). Overall, the available data revealed sixteen genetic loci flagged by single nucleotide polymorphisms (SNPs), none of which has been confirmed yet by independent studies. Moreover, a GWAS for PCOS identified 21 susceptible loci. The genetic architecture is complex which has been revealed by GWAS. Further and larger studies in different populations are required to confirm or disprove results from candidate gene studies as well to identify signals that may overlap between different populations. Finally, studies on rare genetic variants in acne and associated diseases like PCOS may deepen our understanding of its pathogenesis.

PAPA, PASH and PAPASH Syndromes: Pathophysiology, Presentation and Treatment

Pyoderma gangrenosum (PG) is a neutrophilic dermatosis usually manifesting as skin ulcers with undermined erythematous-violaceous borders. It may be isolated, associated with systemic conditions or occurring in the context of autoinflammatory syndromes such as PAPA (pyogenic arthritis, PG and acne), PASH (PG, acne and suppurative hidradenitis) or PAPASH (pyogenic arthritis, acne, PG and suppurative hidradenitis). From a physiopathological point of view, all these conditions share common mechanisms consisting of over-activation of the innate immune system leading to increased production of the interleukin (IL)-1 family and 'sterile' neutrophil-rich cutaneous inflammation. From a genetic point of view, a number of mutations affecting the proteins of the inflammasome complex (the molecular platform responsible for triggering autoinflammation) or the proteins that regulate inflammasome function have been described in these disorders. As these debilitating entities are all associated with the over-expression of IL-1 and tumour necrosis factor (TNF)-α, biological drugs specifically targeting these cytokines are currently the most effective treatments but, given the emerging role of IL-17 in the pathogenesis of these syndromes, IL-17 antagonists may represent the future management of these conditions.

Alarming consequences - autoinflammatory disease spectrum due to mutations in proline-serine-threonine phosphatase-interacting protein 1

PURPOSE OF REVIEW

To give an overview about the expanding spectrum of autoinflammatory diseases due to mutations in proline-serine-threonine phosphatase-interacting protein 1 (PSTPIP1) and new insights into their pathogenesis.

RECENT FINDINGS

In addition to classical pyogenic sterile arthritis, pyoderma gangrenosum, and acne (PAPA) syndrome, PSTPIP1-associated myeloid-related proteinemia inflammatory (PAMI) syndrome has been described as a distinct clinical phenotype of PSTPIP1-associated inflammatory diseases (PAID) and other entities are emerging. In addition to dysregulation of IL-1ß release from activated PAPA monocytes that requires NLR family, pyrin domain containing 3 (NLRP3), PSTPIP1 mutations have an general impact on cellular dynamics of cells of the innate immune system. In addition, overwhelming expression and release of the alarmins myeloid-related protein (MRP) 8 and 14 by activated phagocytes and keratinocytes, which promote innate immune mechanisms in a Toll like receptor (TLR) 4-dependent manner, are a characteristic feature of these diseases and form a positive feed-back mechanism with IL-1ß.

SUMMARY

Autoinflammatory diseases due to PSTPIP1 mutations are not restricted to the classical PAPA phenotype but might present with other distinct clinical features. MRP8/14 serum levels are a hallmark of PAPA and PAMI and can be used as screening tool to initiate targeted genetic testing in suspected cases. The feedback mechanism of IL-1ß and MRP-alarmin release may offer novel targets for future therapeutic approaches.

Posttranslational Modification as a Critical Determinant of Cytoplasmic Innate Immune Recognition

Cell surface innate immune receptors can directly detect a variety of extracellular pathogens to which cytoplasmic innate immune sensors are rarely exposed. Instead, within the cytoplasm, the environment is rife with cellular machinery and signaling pathways that are indirectly perturbed by pathogenic microbes to activate intracellular sensors, such as pyrin, NLRP1, NLRP3, or NLRC4. Therefore, subtle changes in key intracellular processes such as phosphorylation, ubiquitination, and other pathways leading to posttranslational protein modification are key determinants of innate immune recognition in the cytoplasm. This concept is critical to establish the “guard hypothesis” whereby otherwise homeostatic pathways that keep innate immune sensors at bay are released in response to alterations in their posttranslational modification status. Originally identified in plants, evidence that a similar guardlike mechanism exists in humans has recently been identified, whereby a mutation that prevents phosphorylation of the innate immune sensor pyrin triggers a dominantly inherited autoinflammatory disease. It is also noteworthy that even when a cytoplasmic innate immune sensor has a direct ligand, such as bacterial peptidoglycan (NOD1 or NOD2), RNA (RIG-I or MDA5), or DNA (cGAS or IFI16), it can still be influenced by posttranslational modification to dramatically alter its response. Therefore, due to their existence in the cytoplasmic milieu, posttranslational modification is a key determinant of intracellular innate immune receptor functionality.

Pyoderma Gangrenosum: A Current Problem as Much as an Unknown One

Pyoderma gangrenosum (PG) is a rare neutrophilic inflammatory skin disease, characterized by recurrent skin ulcers, which in almost 50% of cases are associated with systemic autoimmune disorders, including rheumatoid arthritis, chronic hepatitis, inflammatory bowel disease, paraproteinemias and hematological malignancies. A systematic search of literature for PG was carried out using the PubMed, Embase, and Google Scholar databases for the purpose of this review and 2780 articles were retrieved up to February 2017. Inflammation represents the predominant aspect of the disease, but its pathophysiological mechanisms are not completely clear yet, since there are many studies showing only one or more isolated findings of the disease. The goal of PG treatment is to reduce inflammation in order to promote ulcer healing by minimizing side effects of therapy. Several systemic and local treatments are available, but the lack of large randomized double-blind studies results in an absence of a uniform therapeutic standard: thus, more clinical studies are required in order to make head-to-head comparisons between combination and single-drug therapies and to identify specific combination therapies for distinctive clinical patterns of PG.

Pyoderma Gangrenosum: An Update on Pathophysiology, Diagnosis and Treatment

Pyoderma gangrenosum (PG) is a rare inflammatory neutrophilic disorder with prototypical clinical presentations. Its pathophysiology is complex and not fully explained. Recent information regarding the genetic basis of PG and the role of auto-inflammation provides a better understanding of the disease and new therapeutic targets. PG equally affects patients of both sexes and of any age. Uncontrolled cutaneous neutrophilic inflammation is the cornerstone in a genetically predisposed individual. Multimodality management is often required to reduce inflammation, optimize wound healing, and treat underlying disease. A gold standard for the management of PG does not exist and high-level evidence is limited. Multiple factors must be taken into account when deciding on the optimum treatment for individual patients: location, number and size of lesion/ulceration(s), extracutaneous involvement, presence of associated disease, cost, and side effects of treatment, as well as patient comorbidities and preferences. Refractory and rapidly progressive cases require early initiation of systemic therapy. Newer targeted therapies represent a promising pathway for the management of PG, and the main focus of this review is the management and evidence supporting the role of new targeted therapies in PG.

Autoinflammation in pyoderma gangrenosum and its syndromic form (pyoderma gangrenosum, acne and suppurative hidradenitis)

BACKGROUND

Pyoderma gangrenosum (PG) is a rare skin disease characterized clinically by ulcers with undermined borders, and histologically by neutrophil-rich infiltrates. PG may occur alone, in syndromic forms or associated with systemic diseases, such as inflammatory bowel disease and haematological or rheumatological disorders.

OBJECTIVES

To determine a specific genetic background related to autoinflammation for PG.

METHODS

We assessed autoinflammation by evaluating the cytokine profile and genes involved in classic autoinflammatory diseases in 13 patients with PG and in seven patients with the syndromic form, known as PASH (pyoderma gangrenosum, acne and suppurative hidradenitis).

RESULTS

In skin samples, the expression of interleukin (IL)-1β and its receptors, IL-17 and its receptor, and tumour necrosis factor-α and its receptors were significantly higher in both PG (P = 0·001) and in PASH (P < 0·001) than in controls. The chemokines IL-8; chemokine (C-X-C motif) ligand 1/2/3; chemokine (C-X-C motif) ligand 16; and RANTES (regulated on activation, normal T-cell-expressed and secreted) were also overexpressed. Cases of PG and PASH showed mutations in the autoinflammatory genes MEFV, NLRP3, NLRP12, NOD2, LPIN2 and PSTPIP1.

CONCLUSIONS

Overexpression of cytokines/chemokines, along with genetic changes, supports the hypothesis that PG and its syndromic form, PASH, are a spectrum of polygenic autoinflammatory conditions.

Monogenic Autoinflammatory Diseases with Mendelian Inheritance: Genes, Mutations, and Genotype/Phenotype Correlations

Autoinflammatory diseases (AIDs) are a genetically heterogeneous group of diseases caused by mutations of genes encoding proteins, which play a pivotal role in the regulation of the inflammatory response. In the pathogenesis of AIDs, the role of the genetic background is triggered by environmental factors through the modulation of the innate immune system. Monogenic AIDs are characterized by Mendelian inheritance and are caused by highly penetrant genetic variants in single genes. During the last years, remarkable progress has been made in the identification of disease-associated genes by using new technologies, such as next-generation sequencing, which has allowed the genetic characterization in undiagnosed patients and in sporadic cases by means of targeted resequencing of a gene panel and whole exome sequencing. In this review, we delineate the genetics of the monogenic AIDs, report the role of the most common gene mutations, and describe the evidences of the most sound genotype/phenotype correlations in AID.

Pyogenic arthritis, pyoderma gangrenosum, and acne (PAPA) syndrome: differential diagnosis of septic arthritis by regular detection of exceedingly high synovial cell counts

Pyogenic arthritis, pyoderma gangrenosum and acne syndrome was diagnosed in a 42-year-old patient, after an unusual persistency of high synovial cell counts had been noticed. Clinical peculiarities and problems with diagnosing septic versus non-septic arthritis are discussed.

Autoinflammatory diseases in adults. Clinical characteristics and prognostic implications

Autoinflammatory diseases are clinical conditions with inflammatory manifestations that present in a periodic or persistent manner and are caused by acquired or hereditary disorders of the innate immune response. In general, these diseases are more common in childhood, but cases have been reported in adults and are therefore important for all specialists. There are few references on these diseases in adults due to their low prevalence and underdiagnosis. The aim of this study is to review the scientific literature on these disorders to systematise their clinical, prognostic and treatment response characteristics in adults.

Pyoderma gangrenosum and its syndromic forms: evidence for a link with autoinflammation

Pyoderma gangrenosum is a rare inflammatory neutrophilic dermatosis manifesting as painful ulcers with violaceous, undermined borders on the lower extremities. It may occur in the context of classic syndromes like PAPA (pyogenic arthritis, pyoderma gangrenosum and acne) and SAPHO (synovitis, acne, pustulosis, hyperostosis, osteitis), as well as in a recently described entity named PASH (pyoderma gangrenosum, acne and suppurative hidradenitis). Pyoderma gangrenosum has recently been included within the spectrum of autoinflammatory diseases, which are characterized by recurrent episodes of sterile inflammation, without circulating autoantibodies and autoreactive T cells. In PAPA syndrome, different mutations involving the PSTPIP1 gene, via an increased binding affinity to pyrin, induce the assembly of inflammasomes. These are molecular platforms involved in the activation of caspase 1, a protease that cleaves inactive prointerleukin (pro-IL)-1β to its active isoform IL-1β. The overproduction of IL-1β triggers the release of a number of proinflammatory cytokines and chemokines, which are responsible for the recruitment and activation of neutrophils, leading to neutrophil-mediated inflammation. In SAPHO syndrome, the activation of the PSTPIP2 inflammasome has been suggested to play a role in inducing the dysfunction of the innate immune system. Patients with PASH have recently been reported to present alterations of genes involved in well-known autoinflammatory diseases, such as PSTPIP1, MEFV, NOD2 and NLRP3. Pyoderma gangrenosum and its syndromic forms can be regarded as a single clinicopathological spectrum in the context of autoinflammation.

Pathophysiology of pyoderma gangrenosum (PG): an updated review

Pyoderma gangrenosum is a challenging skin condition to identify and treat because of its multifactorial pathogenesis. It is a rare cutaneous manifestation diagnosed clinically by exclusion of infection, neoplasia, thrombophilia, and other inflammatory conditions. Pathogenetic and treatment studies are scarce. Abnormalities in the function of inflammatory cytokines, the immune system, and neutrophils combined with specific genetic mutations predispose patients to develop this complex disease process. Early recognition of patients at risk for pyoderma gangrenosum, the necessity to improve its early diagnosis, and the future outlook of targeted and personalized therapies relies on the improved comprehension of the complex pathogenesis of pyoderma gangrenosum.

The SAPHO syndrome revisited with an emphasis on spinal manifestations

The synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome includes a group of chronic, relapsing, inflammatory musculoskeletal disorders with similar manifestations, in particular synovitis, hyperostosis, and osteitis, which may or may not be associated with neutrophilic skin eruptions such as palmoplantar pustulosis and acne conglobata. The syndrome occurs at any age, can involve any skeletal site, and its imaging appearances are variable, depending on the stage/age of the lesion and imaging method. The diagnosis is difficult if there is no skin disease. Awareness of the imaging appearances, especially in the spine, may help the radiologist in avoiding misdiagnosis (e.g., infection, tumor) and unnecessary invasive procedures, while facilitating early diagnosis and selection of an effective treatment. In this article, we provide an overview of the radiological appearances of SAPHO syndrome, focusing on the magnetic resonance imaging findings of vertebral involvement, and present relevant clinical and pathological features that assist early diagnosis.

Untangling the web of systemic autoinflammatory diseases

The innate immune system is involved in the pathophysiology of systemic autoinflammatory diseases (SAIDs), an enlarging group of disorders caused by dysregulated production of proinflammatory cytokines, such as interleukin-1β and tumor necrosis factor-α, in which autoreactive T-lymphocytes and autoantibodies are indeed absent. A widely deranged innate immunity leads to overactivity of proinflammatory cytokines and subsequent multisite inflammatory symptoms depicting various conditions, such as hereditary periodic fevers, granulomatous disorders, and pyogenic diseases, collectively described in this review. Further research should enhance our understanding of the genetics behind SAIDs, unearth triggers of inflammatory attacks, and result in improvement for their diagnosis and treatment.

Management of pyoderma gangrenosum

Pyoderma gangrenosum (PG) is an uncommon ulcerative skin disease often associated with underlying systemic diseases. Its pathogenesis is unknown, although immune pathways have been implicated. Targeted therapy is therefore lacking and currently treatment is largely empirical and consists of corticosteroids and ciclosporin first line. This paper reviews the current and emerging knowledge about PG. PG occurs with an incidence of 3-10 per million per year. The ulcers are exquisitely painful and characteristically have a necrotic centre with irregular overhanging bluish borders. Around half of cases are associated with underlying systemic disease, most commonly inflammatory bowel disease, rheumatoid arthritis and haematological malignancies; the remaining cases are idiopathic. The pathogenesis is unknown, but the most widely supported theory is immunological, and biopsies of lesions show a predominantly neutrophilic infiltrate. Several aberrant immune processes have been described, with neutrophils and their recruitment to sites of inflammation by cytokines taking an apparently important role. Topical and systemic therapies are both vital aspects of treatment, and in recent years, immune modulators have been used with increasing success, with an emerging role for anti-tumour necrosis factor alpha agents such as the monoclonal antibody infliximab. Although uncommon, PG causes significant morbidity to those it affects. Further research is needed into the disease pathogenesis, and adequate targeted treatment.

Autoinflammatory syndromes for the dermatologist

While autoimmunity as cause of disease is well-established, other categories of immune-mediated diseases that are not produced by targeting of self-antigens by antibodies is in the process of being described. These so-called autoinflammatory diseases arise when an inappropriate activation of antigen-independent mechanisms occurs. Autoinflammatory diseases course with recurrent attacks of fever and multisystemic inflammation; however, the skin may also be affected by a variety of inflammatory manifestations that often alert the clinician about the presence of an autoinflammatory disease. Recognizing the cutaneous features of these syndromes will aid for prompt diagnosis and early treatment that is key for the quality of life and survival of the affected patients. In this paper, we focus on the skin manifestations of autoinflammatory diseases in children, which is the usual period of appearing of the first symptoms and signs.

Monogenic autoinflammatory syndromes: state of the art on genetic, clinical, and therapeutic issues

Monogenic autoinflammatory syndromes (MAISs) are caused by innate immune system dysregulation leading to aberrant inflammasome activation and episodes of fever and involvement of skin, serous membranes, eyes, joints, gastrointestinal tract, and nervous system, predominantly with a childhood onset. To date, there are twelve known MAISs: familial Mediterranean fever, tumor necrosis factor receptor-associated periodic syndrome, familial cold urticaria syndrome, Muckle-Wells syndrome, CINCA syndrome, mevalonate kinase deficiency, NLRP12-associated autoinflammatory disorder, Blau syndrome, early-onset sarcoidosis, PAPA syndrome, Majeed syndrome, and deficiency of the interleukin-1 receptor antagonist. Each of these conditions may manifest itself with more or less severe inflammatory symptoms of variable duration and frequency, associated with findings of increased inflammatory parameters in laboratory investigation. The purpose of this paper is to describe the main genetic, clinical, and therapeutic aspects of MAISs and their most recent classification with the ultimate goal of increasing awareness of autoinflammation among various internal medicine specialists.

Gene hunting in autoinflammation

Steady progress in our understanding of the genetic basis of autoinflammatory diseases has been made over the past 16 years. Since the discovery of the familial Mediterranean fever gene MEFV (also known as marenostrin) in 1997, 18 other genes responsible for monogenic autoinflammatory diseases have been identified to date. The discovery of these genes was made through the utilisation of many genetic mapping techniques, including next generation sequencing platforms. This review article clearly describes the gene hunting approaches, methods of data analysis and the technological platforms used, which has relevance to all those working within the field of gene discovery for Mendelian disorders.

A systematic review of SAPHO syndrome and inflammatory bowel disease association

BACKGROUND

The association between inflammatory bowel disease (IBD) and synovitis, acne, pustulosis, hyperostosis, osteitis syndrome (SAPHO syndrome) was first reported in 1992. To date, only case reports and short series have been published.

AIMS

The purpose of this study was to report new cases and systematically review the literature on this association.

MATERIALS AND METHODS

All patients with concomitant diagnosis of SAPHO syndrome and IBD were identified from the databases of the rheumatology and gastroenterology departments of our institution. In addition, we systematically searched for published full articles in Medlars Online International Literature via PubMed. Relevant information of each positive match was collected and all authors were contacted for additional clinical data.

RESULTS

Three patients sharing both SAPHO syndrome and IBD were identified among the 62 patients with SAPHO syndrome (4.8 % of the SAPHO cohort) and the 1,309 patients with IBD (0.2 % of the IBD cohort) from our hospital database. After a systematic review, a total of 39 reported patients with concomitant diagnosis of SAPHO syndrome and IBD were identified. There was a female predominance and most had Crohn's disease with colonic involvement.

CONCLUSIONS

The association of SAPHO syndrome and IBD seems to be rare among IBD patients but not so among SAPHO patients. SAPHO could be underdiagnosed because of the similarity of its clinical manifestations and some more common extraintestinal manifestations or drug-related side effects in IBD.

Autoinflammatory pustular neutrophilic diseases

This article provides a new categorization of inflammatory pustular dermatoses in the context of recent genetic and biological insights. Monogenic diseases with pustular phenotypes are discussed, including deficiency of interleukin 1 receptor antagonist, deficiency of the interleukin 36 receptor antagonist, CARD14-associated pustular psoriasis, and pyogenic arthritis, pyoderma gangrenosum, and acne. How these new genetic advancements may inform how previously described pustular diseases are viewed, including pustular psoriasis and its clinical variants, with a focus on historical classification by clinical phenotype, is also discussed.