PASS: a rare syndrome within the autoinflammatory diseases that still lacks a genetic marker

Hidradenitis Suppurativa-Related Autoinflammatory Syndromes: An Updated Review on the Clinics, Genetics, and Treatment of Pyoderma gangrenosum, Acne and Suppurative Hidradenitis (PASH), Pyogenic Arthritis, Pyoderma gangrenosum, Acne and Suppurative Hidradenitis (PAPASH), Synovitis, Acne, Pustulosis, Hyperostosis and Osteitis (SAPHO), and Rarer Forms

Hidradenitis suppurativa (HS) is an autoinflammatory skin disorder of the terminal hair follicle, which can present in sporadic, familial, or syndromic form. A classification has been proposed for the latter, distinguishing cases associated with a known genetic condition, with follicular keratinization disorders or with autoinflammatory diseases. This review focuses on the clinical and genetic features of those entities (ie, pyoderma gangrenosum [PG], acne and HS; PG, acne, pyogenic arthritis and HS; psoriatic arthritis, PG, acne and HS; synovitis, acne, pustulosis, hyperostosis, osteitis; and so forth) for which the collective term HS-related autoinflammatory syndromes is proposed.

Successful treatment of PASS syndrome with IVIG and anti-IL-1 treatment: A case report

PASS syndrome is a rare autoinflammatory disease characterized by acne vulgaris, hidradenitis suppurativa, pyoderma gangrenosum, and ankylosing spondylitis. Unlike other autoinflammatory disorders such as PAPA and PASH syndrome, there is no documented gene mutation link. Although there are no established treatment guidelines due to the rarity of these diseases, systemic corticosteroids, biologics, and immunosuppressive drugs are used currently. In our report, we presented a case of PASS syndrome who was unresponsive to adalimumab and in whom we observed improvement in both skin and joint manifestations with intravenous immunoglobulin (IVIG) and anti-IL-1 treatment.

The pyrin inflammasome, a leading actor in pediatric autoinflammatory diseases

The activation of the pyrin inflammasome represents a highly intriguing mechanism employed by the innate immune system to effectively counteract pathogenic agents. Despite its key role in innate immunity, pyrin has also garnered significant attention due to its association with a range of autoinflammatory diseases (AIDs) including familial Mediterranean fever caused by disruption of the MEFV gene, or in other genes involved in its complex regulation mechanisms. Pyrin activation is strictly dependent on homeostasis-altering molecular processes, mostly consisting of the disruption of the small Ras Homolog Family Member A (RhoA) GTPases by pathogen toxins. The downstream pathways are regulated by the phosphorylation of specific pyrin residues by the kinases PKN1/2 and the binding of the chaperone 14-3-3. Furthermore, a key role in pyrin activation is played by the cytoskeleton and gasdermin D, which is responsible for membrane pores in the context of pyroptosis. In addition, recent evidence has highlighted the role of steroid hormone catabolites and alarmins S100A8/A9 and S100A12 in pyrin-dependent inflammation. The aim of this article is to offer a comprehensive overview of the most recent evidence on the pyrin inflammasome and its molecular pathways to better understand the pathogenesis behind the significant group of pyrin-related AIDs.

Hidradenitis suppurativa: Detangling phenotypes and identifying common denominators

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

Synovitis, Acne, Pustulosis, Hyperostosis, and Osteitis (SAPHO) Syndrome with Cutis Verticis Gyrata: Case Report and Review of Literature

SAPHO (synovitis, acne, pustulosis, hyperostosis, and osteitis) syndrome is a rare disease clinically characterized by a wide range of cutaneous and osteoarticular manifestations. Here, we report a case of SAPHO syndrome with cutis verticis gyrata (CVG) and investigated the genetic causes in the four members of this pedigree. After failure of conventional treatments, a recombinant human TNF-α receptor II:IgG Fc fusion protein (rhTNFR:Fc, YISAIPU^®) achieved good control of the disease at the 2-year follow-up. We did not identify any pathogenic mutation in this pedigree. We also summarized the clinical and therapeutic characteristics of 83 patients with SAPHO syndrome through the China National Knowledge Infrastructure (CKNI) database from 2016 to 2021. Patients with acne were young and predominantly male. About 45.8% patients were treated with biological therapies or traditional Chinese medicine (TCM), 84.2% of which showed positive effects against cutaneous and osteoarticular manifestations. We report a case of SAPHO syndrome with CVG that was successfully treated with rhTNFR:Fc. Our results reveal the genetic heterogeneity involved. Biologics and TCM are likely alternative options for the treatment of SAPHO syndrome.

Secukinumab for PASS Syndrome: A new choice for therapeutic challenge?

PASS syndrome is a rare inflammatory disease characterized by a chronic-relapsing course of pyoderma gangrenosum, acne vulgaris, hidradenitis suppurativa, and spondyloarthritis, which is lack of any biological or genetic marker. Moreover, the optimal therapeutic management remains unclear. We herein describe a Yi Chinese man with PASS syndrome who was treated with secukinumab and showed a remarkable response with almost complete clinical improvement at the 2-year follow-up.

Insights into hidradenitis suppurativa

Hidradenitis suppurativa (HS) is a chronic, debilitating, inflammatory skin disorder with a prevalence of around 1% and a profound impact on patients' quality of life. Characteristic lesions such as inflammatory nodules, abscesses, and sinus tracts develop in the axillae, inguinal, and gluteal areas, typically during or after puberty. A complex interplay of genetic predisposition, hormonal factors, obesity, and smoking contributes to development and maintenance of the disease. HS is considered to arise from an intrinsic defect within the hair follicle, leading to follicular plugging, cyst formation, and subsequent rupture that in turn induce an acute inflammatory response characterized by elevated levels of IL-1β, IL-17, and TNF. Over time, acute lesions transition into chronic disease, with active draining sinus tracts accompanied by extensive fibrosis. HS is associated with other immune-mediated inflammatory diseases, metabolic and cardiovascular disorders, and psychiatric comorbidities. Treatment of HS often requires a combination of antibiotic or immunosuppressing therapies and surgical intervention. Nonetheless, the currently available treatments are not universally effective, and many drugs, which are often repurposed from other inflammatory diseases, are under investigation. Studies into the early stages of HS may yield treatments to prevent disease progression; yet, they are hampered by a lack of appropriate in vitro and animal models.