Pyoderma gangrenosum following anti-TNF therapy in chronic recurrent multifocal osteomyelitis: drug reaction or cutaneous manifestation of the disease? A critical review on the topic with an emblematic case report

Update on the diagnosis and treatment of CNO in children: a clinician's perspective

Chronic non-bacterial osteomyelitis (CNO) is caused by aseptic inflammation of bones, primarily driven by the innate immune system. CNO may display different clinical presentations (acute vs chronic, uni- vs multifocal) and is accompanied by other inflammatory disorders in up to a third of patients. Once considered a rare disorder, it has become clear that many patients were underdiagnosed. With increasing awareness and the development of total-body MRI protocols, CNO recognition and diagnosis have greatly improved. Our knowledge of the clinical manifestations and outcomes of CNO has been refined in recent years, especially thanks to the recruitment of large international series. Similarly, new insights into the pathogenesis have been gained by the development of mice models and identification of rare monogenic diseases that resemble CNO. Unfortunately, these advances have not been paralleled in the therapeutic management. In the absence of prospective controlled trials, therapeutic strategies still rely on low-level evidence studies. About half of the patients respond to first-line therapies, but a more refractory and/or chronic disease course requires additional treatments. This narrative review aims to provide the practicing physician with an update on CNO pathogenesis, clinical presentation, associated inflammatory conditions, and diagnostic investigations, and includes a concise summary of current therapeutic recommendations.

CONCLUSION

While major progresses have been made in the recognition and management of CNO, significant challenges remain, in particular regarding the treatment of refractory patients, and those with associated inflammatory disorders.

WHAT IS KNOWN

• Many physicians caring for children will encounter patients suffering of (suspected) CNO. CNO diagnosis requires exclusion of numerous conditions included in the differential diagnosis, which may be challenging.

WHAT IS NEW

• We provide an updated review of recent findings in the field CNO, including imaging and diagnostic strategies, associated inflammatory diseases and long-term outcomes data. • We focus particularly on the challenges encountered by clinicians in the diagnosis and treatment of these patients. • We highlight knowledge gaps in the understanding and treatment of CNO, that should stimulate future research.

Human Inborn Errors of Immunity in Pyoderma Gangrenosum: A Systematic Review

BACKGROUND AND OBJECTIVE

Pyoderma gangrenosum (PG) is a rare ulcerative neutrophilic dermatosis that can be associated with primary immunodeficiency. The pathogenesis of PG has not yet been elucidated, although contributions from dysregulation of the immune system in patients with apparent genetic predispositions have been postulated. We conducted a Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)-guided systematic review with the objective of identifying inborn errors of immunity in the presence of PG as well as their clinical characteristics of severity including number of PG lesions and anatomic areas affected, and treatment outcomes.

METHODS

A literature search was performed using PubMed/MEDLINE, Embase, Cochrane Library, and Web of Science through August 24, 2023, for studies published in English using the search terms: "pyoderma gangrenosum," "inborn error of immunity," "immune defect*," and a list of genetic mutations potentially associated with PG.

RESULTS

Seventy-four cases of PG associated with inborn errors of immunity were identified. The results demonstrate an association of PG with a variety of inborn errors of immunity, including genetic mutations not classically associated with the condition. Genetic mutations such as BTK, IL1RN, ITGB2, LPIN2, MEFV, NFkB1, NLRP3, NLRP12, NOD2, PSMB8, PLCG2, PSTPIP1, RAG1, TTC37, and WDR1, as well as complement component 2/complement component 4 (C2/C4) and complement component 7 (C7) deficiencies were identified in the presence of either idiopathic or syndromic PG. Of note, mutations in genes such as PSMB8, NLRP3, and IL1RN were found to be associated with a more severe and atypical course of PG, whereas mutations in RAG1 as well as those causing a C2/C4 deficiency were associated with the mildest clinical presentations of PG. Mutations in NFkB1, ITGB2, and PSTPIP1 were associated with the most heterogeneous clinical presentations.

CONCLUSIONS

Human inborn errors of immunity may be implicated in the genetic predisposition to PG and may influence the clinical presentation. Due to the rarity of these diseases, further work must be done to describe the association between inborn errors of immunity and PG. Identifying inborn errors of immunity that may contribute to the development of PG may assist in further elucidating the mechanism of PG, guiding targeted treatment, and improving clinical outcomes for these patients.

Paradoxical Psoriasis in Patients Receiving Therapy with Tumor Necrosis Factor Inhibitors: Potential Pathogenic Mechanisms and the Role of Genetic Factors

TNF inhibitors (TNFi) have revolutionized the therapeutic management of various chronic immune-mediated inflammatory diseases. Despite their known benefits, these therapies are related to paradoxical adverse effects (PAEs), including paradoxical psoriasis (PP). Although the underlying mechanism remains somewhat unclear, some theories suggest that genetic factors, particularly certain single-nucleotide polymorphisms (SNPs), may play an important role. The present review aimed to research and analyze recent findings regarding the pathomechanisms involved in the appearance of PP and the association between various genetic factors and PP in individuals treated with TNFi. We performed a literature search and found that certain genes (IL23R, TNF, FBXL19, CTLA4, SLC12A8, TAP1) are strongly associated with the occurrence of PP in pediatric and adult patients during therapy with TNFi. The identification of the specific SNPs involved in the appearance of PP and other PAEs in patients treated with TNFi for various diseases and in different populations may later favor the recognition of those patients at a high risk of developing such adverse effects and could guide personalized therapeutic strategies in future years.

Certolizumab treatment of localized pyoderma gangrenosum in a pregnant patient

THE PURPOSE OF THE ARTICLE

Pyoderma gangrenosum (PG) is an ulcerating neutrophilic dermatosis with an incidence of 3-10 patients per million. PG equally affects patients of both sexes and of any age. Of these patients, 50-75% are associated with auto-immune disease. The lower extremities are the most commonly affected body parts. Minor trauma to the skin may result in the development of new lesions. Patients complain of chronic, nonhealing ulcers with associated pain. Treatment starts with systemic or intralesional corticosteroids, however, no official treatment protocol currently exists. Recent success has been found with biologic agents such as TNF-a inhibitor, although the treatment efficacy in these reports is limited. As for the pregnant patient, the drug selection is difficult. In this report, we want to assess the efficiency of certolizumab in the pregnant patient.

RESULTS

We report a case of a patient with PG, who responded well to certolizumab, 400 mg as a booster dose, followed by 200 mg biweekly for 8 weeks. The lesions gradually resolved and followed up for 5months without side effect. In addition, we reviewed the literature and compared the current treatment efficiency in the treatment of PG.

CONCLUSION

Certolizumab may be a promising therapeutic option for patients with severe PG.

From Molecular Insights to Clinical Perspectives in Drug-Associated Bullous Pemphigoid

Bullous pemphigoid (BP), the most common autoimmune blistering disease, is characterized by the presence of autoantibodies targeting BP180 and BP230 in the basement membrane zone. This leads to the activation of complement-dependent and independent pathways, resulting in proteolytic cleavage at the dermoepidermal junction and an eosinophilic inflammatory response. While numerous drugs have been associated with BP in the literature, causality and pathogenic mechanisms remain elusive in most cases. Dipeptidyl peptidase 4 inhibitors (DPP4i), in particular, are the most frequently reported drugs related to BP and, therefore, have been extensively investigated. They can potentially trigger BP through the impaired proteolytic degradation of BP180, combined with immune dysregulation. DPP4i-associated BP can be categorized into true drug-induced BP and drug-triggered BP, with the latter resembling classic BP. Antineoplastic immunotherapy is increasingly associated with BP, with both B and T cells involved. Other drugs, including biologics, diuretics and cardiovascular and neuropsychiatric agents, present weaker evidence and poorly understood pathogenic mechanisms. Further research is needed due to the growing incidence of BP and the increasing identification of new potential triggers.