Dermatologic and Dermatopathologic Features of Monogenic Autoinflammatory Diseases

Immuno-inflammatory involvement of adipose tissue in children

Adipose tissue is a highly immunologically active tissue that can be involved in many inflammatory diseases. In this presentation, only adipose tissue disorders associated with inflammatory diseases in children will be described, with the exception of obesity.

Update on ocular manifestations of the main monogenic and polygenic autoinflammatory diseases

Autoinflammatory diseases include disorders with a genetic cause and also complex syndromes associated to polygenic or multifactorial factors. Eye involvement is present in many of them, with different extent and severity. The present review covers ophthalmological lesions in the most prevalent monogenic autoinflammatory diseases, including FMF (familial Mediterranean fever), TRAPS (TNF receptor-associated periodic syndrome), CAPS (cryopyrin-associated periodic syndromes), Blau syndrome, DADA2 (deficiency of adenosine deaminase 2), DITRA (deficiency of the interleukin-36 receptor antagonist), other monogenic disorders, including several ubiquitinopathies, interferonopathies, and the recently described ROSAH (retinal dystrophy, optic nerve edema, splenomegaly, anhidrosis, and headache) syndrome, and VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) syndrome. Among polygenic autoinflammatory diseases, ocular manifestations have been reviewed in Behçet's disease, PFAPA (periodic fever, aphthous stomatitis, pharyngitis and cervical adenitis) syndrome, Still's disease and autoinflammatory bone diseases, which encompass CRMO (chronic recurrent multifocal osteomyelitis) and SAPHO (synovitis, acne, pustulosis, hyperostosis and osteitis) syndrome.

Early-onset recurrent panniculitis as a phenotype of NLRC4-associated autoinflammatory syndrome: Characterization of pathogenicity of the p.Ser445Pro NLRC4 variant

Monoallelic NLRC4 gain-of-function variants cause an inflammasomopathy with diverse clinical forms including infantile enterocolitis, recurrent macrophage activation syndrome, cold-induced urticaria-like lesions (or familial-cold autoinflammatory syndrome, FCAS4), and painful subcutaneous nodules. Here, we identified a large family with six consecutive generations affected. Genetic analyses detected the heterozygous p.Ser445Pro NLRC4 variant in three patients, which has been previously reported in a Dutch family with FCAS4. We aimed to describe the clinicopathological features and the functional consequences of the detected NLRC4 variant. Patients presented an early-onset (3 months-6 years) inflammatory disease characterized by recurrent panniculitis, fever and arthralgia. Histopathological examination showed perivascular and interstitial lymphohistiocytic infiltrates in the dermis and mixed panniculitis. Functional analysis supported the conclusion that the p.Ser445Pro NLRC4 variant leads to a constitutive activation of NLRC4-inflammasome and increased plasma levels of IL-18. Prompt recognition of early-onset panniculitis through clinicopathological examination and laboratory biomarkers may allow targeted therapies.

Dermatologic Manifestations of Noninflammasome-Mediated Autoinflammatory Diseases

Autoinflammatory diseases (AIDs) arise from disturbances that alter interactions of immune cells and tissues. They give rise to prominent (auto)inflammation in the absence of aberrant autoantibodies and/or autoreactive T cells. AIDs that are predominantly caused by changes in the inflammasome pathways, such as the NLRP3- or pyrin-associated inflammasome, have gained substantial attention over the last years. However, AIDs resulting primarily from other changes in the defense system of the innate immune system are less well-studied. These noninflammasome-mediated AIDs relate to, for example, disturbance in the TNF or IFN signaling pathways or aberrations in genes affecting the IL-1RA. The spectrum of clinical signs and symptoms of these conditions is vast. Thus, recognizing early cutaneous signs constitutes an important step in differential diagnoses for dermatologists and other physicians. This review provides an overview of the pathogenesis, clinical presentation, and available treatment options highlighting dermatologic aspects of noninflammasome-mediated AIDs.

Disease Association of Anti‒Carboxyethyl Lysine Autoantibodies in Hidradenitis Suppurativa

Hidradenitis suppurativa (HS) is a chronic inflammatory skin disease characterized by recurring suppurating lesions of the intertriginous areas, resulting in a substantial impact on patients' QOL. HS pathogenesis remains poorly understood. An autoimmune component has been proposed, but disease-specific autoantibodies, autoantigens, or autoreactive T cells have yet to be described. In this study, we identify a high prevalence of IgM, IgG, and IgA antibodies directed against Nε-carboxyethyl lysine (CEL), a methylglyoxal-induced advanced glycation end-product, in the sera of patients with HS. Titers of anti-CEL IgG and IgA antibodies were highly elevated in HS compared with those in healthy controls and individuals with other inflammatory skin diseases. Strikingly, the majority of anti-CEL IgG was of the IgG2 subclass and correlated independently with both disease severity and duration. Both CEL and anti-CEL‒producing plasmablasts could be isolated directly from HS skin lesions, further confirming the disease relevance of this autoimmune response. Our data point to an aberration of the methylglyoxal pathway in HS and support an autoimmune axis in the pathogenesis of this debilitating disease.

Performance of recent PRINTO criteria versus current ILAR criteria for systemic juvenile idiopathic arthritis: A single-centre experience

OBJECTIVES

The purpose of this study is to evaluate the performances of recently proposed Pediatric Rheumatology International Trials Organization criteria versus current International League of Associations for Rheumatology criteria for systemic juvenile idiopathic arthritis (sJIA).

METHODS

The study was performed at the Department of Pediatric Rheumatology in Istanbul Faculty of Medicine with a retrospective design, covering the date range 2010-2021. Patients diagnosed with sJIA, Kawasaki disease and common autoinflammatory diseases were included. Both the International League of Associations for Rheumatology and Pediatric Rheumatology International Trials Organization classification criteria were applied to each patient and cross-checked with expert rheumatologist diagnosis.

RESULTS

Eighty-two patients with sJIA were compared against 189 (74 Kawasaki disease, 83 familial Mediterranean fever, 16 mevalonate kinase deficiency, 10 cryopyrin-associated periodic syndromes, and 6 tumour necrosis factor receptor-associated periodic syndrome) patients. The Pediatric Rheumatology International Trials Organization criteria demonstrated higher sensitivity (62.2% vs 80.5%, P =.003) but comparable specificity (90.5% vs 91%) as regards the International League of Associations for Rheumatology criteria.

CONCLUSIONS

The revised criteria appear to enhance the ability to provide early recognition and pertinent classification of sJIA. No superiority was observed in segregating sJIA from common autoinflammatory diseases and Kawasaki disease, namely in terms of specificity.

Autoimmune and autoinflammatory diseases with mucocutaneous manifestations: A pediatric rheumatology perspective

The presence of mucocutaneous manifestations has clinical significance, as it may be a part of the initial presentation or activation stage of both autoimmune and autoinflammatory rheumatic diseases. The cutaneous signs may display a particular morphological and topographic distribution according to taxonomy, whereas heterogeneity is likely observed among the individuals. The review aims to cluster and systematically approach the mucocutaneous manifestations met in autoimmune and autoinflammatory rheumatic diseases of childhood. The search strategy involved a comprehensive inquiry on Web of Science, PubMed, MEDLINE, and Embase databases using relevant search terms such as "dermatologic, cutaneous, mucocutaneous, skin, rash" for each disease and category. The awareness of the distinctive mucocutaneous manifestations and their correlation with rheumatic diseases provides a convenient definition, well-timed control of the underlying condition, and prevention of cosmetic issues. In the management of rheumatic diseases, planning the pertinent differential diagnosis and determining the requirement of histopathological assessment are essential with a multidisciplinary approach to rheumatology, dermatology, and allergy-immunology specialties.

Skin immunity: dissecting the complex biology of our body's outer barrier

Our skin contributes critically to health via its role as a barrier tissue, carefully regulating passage of key substrates while also providing defense against exogenous threats. Immunological processes are integral to almost every skin function and paramount to our ability to live symbiotically with skin commensal microbes and other environmental stimuli. While many parallels can be drawn to immunobiology at other mucosal sites, skin immunity demonstrates unique features that relate to its distinct topography, chemical composition and microbial ecology. Here we provide an overview of skin as an immune organ, with reference to the broader context of mucosal immunology. We review paradigms of innate as well as adaptive immune function and highlight how skin-specific structures such as hair follicles and sebaceous glands interact and contribute to these processes. Finally, we highlight for the mucosal immunology community a few emerging areas of interest for the skin immunity field moving forward.

Cutaneous signs and mechanisms of inflammasomopathies

The emerging group of autoinflammatory diseases (AIDs) is caused by a dysregulation of the innate immune system while lacking the typical footprint of adaptive immunity. A prominent subgroup of AIDs are inflammasomopathies, which are characterised by periodic flares of cutaneous signs as well as systemic organ involvement and fever. The range of possible skin lesions is vast, ranging from urticarial, erysipelas-like and pustular rashes to erythematous patches, violaceous plaques and eventual necrosis and ulceration. This review provides a structured overview of the pathogenesis and the clinical picture with a focus on dermatological aspects of inflammasomopathies. Current treatment options for these conditions are also discussed.

Cutaneous eccrine inflammation and necrosis: review of inflammatory disorders affecting the eccrine apparatus including new associations

Despite being frequently overlooked during the examination of histopathological sections, eccrine sweat glands can offer clues for diagnosing various skin conditions. They provide important functions and can lead to several diseases when inflamed or injured. This review article provides information regarding eccrine physiology as well as well-established and novel entities that occur in association with eccrine gland pathology.

Panniculitis in Children

Panniculitides form a heterogenous group of inflammatory diseases that involve the subcutaneous adipose tissue. These disorders are rare in children and have many aetiologies. As in adults, the panniculitis can be the primary process in a systemic disorder or a secondary process that results from infection, trauma or exposure to medication. Some types of panniculitis are seen more commonly or exclusively in children, and several new entities have been described in recent years. Most types of panniculitis have the same clinical presentation (regardless of the aetiology), with tender, erythematous subcutaneous nodules. Although the patient's age and the lesion site provide information, a histopathological assessment is sometimes required for a definitive diagnosis and classification of the disorder. In children, most panniculitides are lobular. At present, autoimmune inflammatory diseases and primary immunodeficiencies have been better characterised; panniculitis can be the presenting symptom in some of these settings. Unexplained panniculitis in a young child should prompt a detailed screen for monogenic immune disorders because the latter usually manifest themselves early in life. Here, we review forms of panniculitis that occur primarily in children, with a focus on newly described entities.

Histologic Patterns and Clues to Autoinflammatory Diseases in Children: What a Cutaneous Biopsy Can Tell Us

Autoinflammation is defined by aberrant, antigen-independent activation of the innate immune signaling pathways. This leads to increased, pro-inflammatory cytokine expression and subsequent inflammation. In contrast, autoimmune and allergic diseases are antigen-directed immune responses from activation of the adaptive immune system. The innate and adaptive immune signaling pathways are closely interconnected. The group of 'complex multigenic diseases' are a result of mutual dysregulation of both the autoinflammatory and autoimmune physiologic components. In contrast, monogenic autoinflammatory syndromes (MAIS) result from single mutations and are exclusively autoinflammatory in their pathogenesis. Studying the clinical and histopathological findings for the various MAIS explains the phenotypical correlates of their specific mutations. This review aims to group the histopathologic clues for autoinflammation into three recognizable patterns. The presence of these histologic patterns in a pediatric patient with recurrent fevers and systemic inflammation should raise suspicion of an autoinflammatory component in MAIS, or, more frequently, in a complex multigenic disease. The three major histopathological patterns seen in autoinflammation are as follows: (i) the 'neutrophilic' pattern, seen in urticarial neutrophilic dermatosis, pustular psoriasis, aseptic neutrophilic folliculitis, and Sweet's syndrome; (ii) the 'vasculitic' pattern seen in small vessel-vasculitis (including hypersensitivity/leukocytoclastic vasculitis, thrombosing microangiopathy and lymphocytic vasculitis), and intermediate-sized vessel vasculitis, mimicking polyarteritis nodosa; and (iii) the 'granulomatous' pattern. Beyond these three patterns, there are additional histopathologic clues, which are detailed below. It is important for a dermatopathologist to recognize the patterns of autoinflammation, so that a diagnosis of MAIS or complex multigenic diseases may be obtained. Finally, careful histopathologic analyses could contribute to a better understanding of the various clinical manifestations of autoinflammation.

Systematic evaluation of nine monogenic autoinflammatory diseases reveals common and disease-specific correlations with allergy-associated features

BACKGROUND

Monogenic autoinflammatory diseases (AID) are caused by mutations in innate immune genes. The effects of these mutations on allergic inflammation are unknown.

OBJECTIVES

We investigated allergic, immunological and clinical phenotypes in FMF (familial Mediterranean fever), CAPS (cryopyrin-associated periodic syndrome), TRAPS (tumour necrosis factor receptor-associated periodic syndrome), HIDS (hyper-IgD syndrome), PAPA (pyogenic arthritis, pyoderma gangrenosum and acne), DADA2 (deficiency of adenosine deaminase 2), HA20 (haploinsufficiency of A20), CANDLE (chronic atypical neutrophilic dermatosis, lipodystrophy, elevated temperature) and SAVI (STING-associated vasculopathy of infancy).

METHODS

In this cross-sectional study, clinical data were assessed in 425 patients with AID using questionnaires and chart reviews. Comparator data were obtained from public databases. Peripheral blood mononuclear cells obtained from 55 patients were stimulated and CD4⁺ cytokine production assessed.

RESULTS

Clinical laboratory features of Type 2 immunity were elevated in CAPS but reduced in most AID, particularly DADA2. Physician-diagnosed allergic diseases were prevalent in multiple AID, including CAPS and DADA2. T helper 2 (Th2) cells were expanded in CAPS, TRAPS and HIDS; Th9 cells were expanded in HA20.

CONCLUSIONS

CAPS is characterised by an enhanced Type 2 signature, whereas FMF and CANDLE are associated with reduced Type 2 responses. DADA2 is associated with reduced Type 2 responses but a high rate of physician-diagnosed allergy. Therefore, NLRP3-driven autoinflammation may promote Type 2 immunity, whereas AID like DADA2 may manifest clinical phenotypes that masquerade as allergic disorders. Further investigations are needed to determine the contribution of autoinflammation to allergic clinical and immunological phenotypes, to improve the treatment of patients with AID.

Neutrophilic dermatosis: a new skin manifestation and novel pathogenic variant in a rare autoinflammatory disease

Sideroblastic anaemia, B-cell immunodeficiency, periodic fever and developmental delay (SIFD) is caused by mutations of TRNT1, an enzyme essential for mitochondrial protein synthesis, and has been reported in 23 cases. A 6-month-old girl was evaluated with recurrent fever, failure to thrive, skin lesions and anaemia. She received blood transfusions and empirical antibiotics. Skin lesions, previously interpreted as insect bites, consisted of numerous firm asymptomatic erythematous papules and nodules, distributed over trunk and limbs. Skin histopathology revealed an intense dermal neutrophilic infiltrate extending to the subcutaneous, with numerous atypical myeloid cells, requiring the diagnosis of leukaemia cutis, to be ruled out. Over the follow-up, she developed herpetic stomatitis, tonsillitis, lobar pneumonia and Metapneumovirus tracheitis, and also deeper skin lesions, resembling panniculitis. Hypogammaglobulinaemia was diagnosed. An autoinflammatory disease was confirmed by whole exome sequencing: heterozygous mutations for TRNT1 NM_182916 c.495_498del, p.F167Tfs * 9 and TRNT1 NM_182916 c.1246A>G, p.K416E. The patient has been treated with subcutaneous immunoglobulin and etanercept. She presented with developmental delay and short stature for age. The fever, anaemia, skin neutrophilic infiltration and the inflammatory parameters improved. We describe a novel mutation in SIFD and the first to present skin manifestations, namely neutrophilic dermal and hypodermal infiltration.

Cutaneous clues to diagnose autoinflammatory diseases

Systemic autoinflammatory diseases (AIDs) are a group of disorders characterized by recurrent episodes of systemic inflammation. Suspecting the diagnosis can be difficult and many of the clinical manifestations are common to different diseases. Although most of the cutaneous manifestations are non-specific, it is important to know them because sometimes they can lead to the diagnosis. The purpose of this review was to synthesize the main cutaneous lesions of autoinflammatory diseases to aid in their diagnosis.

Skin Manifestations in COVID-19: Prevalence and Relationship with Disease Severity

BACKGROUND

Data on the clinical patterns and histopathology of SARS-CoV-2 related skin lesions, as well as on their relationship with the severity of COVID-19 are limited.

METHODS AND MATERIALS

Retrospective analysis of a prospectively collected cohort of patients with SARS-CoV-2 infection in a teaching hospital in Barcelona, Spain, from 1 April to 1 May 2020. Clinical, microbiological and therapeutic characteristics, clinicopathological patterns of skin lesions, and direct immunofluorescence and immunohistochemical findings in skin biopsies were analyzed.

RESULTS

Fifty-eight out of the 2761 patients (2.1%) either consulting to the emergency room or admitted to the hospital for COVID-19 suspicion during the study period presented COVID-19 related skin lesions. Cutaneous lesions could be categorized into six patterns represented by the acronym "GROUCH": Generalized maculo-papular (20.7%), Grover's disease and other papulo-vesicular eruptions (13.8%), livedo Reticularis (6.9%), Other eruptions (22.4%), Urticarial (6.9%), and CHilblain-like (29.3%). Skin biopsies were performed in 72.4%, including direct immunofluorescence in 71.4% and immunohistochemistry in 28.6%. Patients with chilblain-like lesions exhibited a characteristic histology and were significantly younger and presented lower rates of systemic symptoms, radiological lung infiltrates and analytical abnormalities, and hospital and ICU admission compared to the rest of patients.

CONCLUSION

Cutaneous lesions in patients with COVID-19 appear to be relatively rare and varied. Patients with chilblain-like lesions have a characteristic clinicopathological pattern and a less severe presentation of COVID-19.

[Vesicles, pustules and vesiculopustules in early childhood]

Vesicles, pustules and vesiculopustules are frequent in newborns and infants and mostly self-limiting. In order to differentiate the rare life-threatening diseases and to therefore initiate the treatment in a timely manner, knowledge of vesicular, pustular and vesiculopustular dermatoses in early childhood is necessary.

Phenotype variability of autoinflammatory disorders in the pediatric patient: A pictorial overview

Disruption of innate immunity leading to systemic inflammation and multi-organ dysfunction is the basilar footprint of autoinflammatory disorders (AIDs), ranging from rare hereditary monogenic diseases to a large number of common chronic inflammatory conditions in which there is a simultaneous participation of multiple genetic components and environmental factors, sometimes combined with autoimmune phenomena and immunodeficiency. Whatever their molecular mechanism, hereditary AIDs are caused by mutations in regulatory molecules or sensors proteins leading to dysregulated production of proinflammatory cytokines or cytokine-inducing transcription factors, fever, elevation of acute phase reactants, and a portfolio of manifold inflammatory signs which might occur in a stereotyped manner, mostly with overactivity or misactivation of different inflammasomes. Symptoms might overlap in the pediatric patient, obscuring the final diagnosis of AIDs and delaying the most appropriate treatment. Actually, the fast-paced evolution of scientific knowledge has led to recognize or reclassify an overgrowing number of multifactorial diseases, which share the basic pathogenetic mechanisms with AIDs. The wide framework of classic hereditary periodic fevers, AIDs with prominent skin involvement, disorders of the ubiquitin-proteasome system, defects of actin cytoskeleton dynamics, and also idiopathic nonhereditary febrile syndromes occurring in children is herein presented. Interleukin-1 dependence of these diseases or involvement of other predominating molecules is also discussed.

NLRP12 gene mutations and auto-inflammatory diseases: ever-changing evidence

Systemic auto-inflammatory diseases (SAID) are a group of rare inherited conditions characterized by a dysregulation of the immune system and associated with recurrent episodes of fever and systemic inflammation. Patients with NLRP12 variants develop a rare autosomal dominant condition known as familial cold-induced autoinflammatory syndrome (FCAS2, OMIM #611762) that has been related to several different clinical manifestations including autoimmunity and immune deficiencies. In past years, several new variants have been described; however, their clinical relevance is sometimes uncertain, especially when they have been detected in healthy subjects. To our knowledge 61 patients with NLRP12 variants have been reported so far in the literature. Here we report the case of a 33-year-old woman with a history of recurrent fever and symmetric and additive poly-arthritis, fulfilling diagnostic criteria for RA, who was found to harbour two variants in the NLRP12 gene (OMIM *609648) and provide a review of the literature on similar cases.