Neutrophilic urticarial dermatosis: A review

Neutrophilic Urticarial Dermatosis: A Window into Systemic Inflammation and Autoimmune Disorders

Neutrophilic urticarial dermatosis (NUD) is a distinctive dermatological manifestation that is commonly associated with systemic autoinflammatory and autoimmune diseases. This review comprehensively explores NUD in the context of five major conditions: Schnitzler syndrome, Still's disease, cryopyrin-associated periodic syndrome, systemic lupus erythematosus, and VEXAS syndrome. For each condition, a detailed discussion of the underlying mechanisms, clinical presentations, diagnostic criteria, and treatment strategies is provided. In addition, cases exhibiting features similar to NUD are emphasized, with a comprehensive examination of the pathological characteristics, particularly focusing on neutrophilic epitheliotropism. This review underscores the significance of identifying NUD as a potential indicator of systemic autoimmune disorders and discusses the role of skin biopsy and laboratory tests in diagnosing the underlying etiology. Finally, a diagnostic framework for NUD is proposed, highlighting the importance of a multidisciplinary assessment to ascertain the underlying systemic condition responsible for the dermatological manifestations. The objective of this review is to enhance the comprehension of NUD, thereby facilitating early diagnosis and the implementation of targeted strategies for affected patients.

Conceptual Contextualization of Neutrophilic Dermatoses

ABSTRACT

Neutrophilic dermatoses are defined as inflammatory skin diseases characterized by sterile infiltration of polymorphonuclear neutrophils into various cutaneous layers. Although, in many cases, neutrophilic dermatoses represent the cutaneous counterpart of autoinflammatory diseases, this is not always the case, and there are other causes associated with this group of diseases, such as the administration of certain drugs or an underlying tumor. However, understanding the autoinflammatory context in which most of these entities develop, as well as their close relationship with autoimmunity, is key to comprehending their pathogenesis. In addition, understanding the mechanisms by which neutrophils migrate to the dermis and become activated is fundamental for interpreting the morphological findings of these biopsies. Finally, the description of a new group of neutrophilic dermatoses in recent years, in relation to keratinization disorders, has been crucial for understanding the best therapeutic approach for these difficult-to-manage entities.

Dapsone Use in Dermatology

Dapsone, initially synthesized for textile dyeing, gained recognition in the 1930s for its antibacterial properties, leading to its utilization in dermatology for leprosy and dermatitis herpetiformis. Despite US Food and Drug Administration (FDA) approval for these conditions, dapsone's off-label uses have expanded, making it a valuable option in various dermatologic conditions. This review seeks to highlight the common uses of dapsone in its FDA indications and off-label indications. Diseases in which dapsone is considered first-line therapy or adjunctive therapy are reviewed, with highlights from the resources included. An overview of dapsone's pharmacokinetics, pharmacodynamics, indications, dosages, and safety profile are also reviewed. Dapsone's versatility and safety profile make it a cost-effective treatment option in dermatology, particularly for patients with limited access to specialized medications. Ongoing clinical trials are also described exploring dapsone's efficacy in novel dermatologic uses. Dapsone has been a valuable adjunctive therapy across various dermatologic conditions for years and evidence for its use continues to expand.

Isolated Neutrophilic Urticarial Dermatosis in a Previously Healthy Male: A Case Report

Neutrophilic urticarial dermatosis (NUD), a variant falling under the larger umbrella of neutrophilic dermatoses (NDs), is characterized by distinctive clinical and histopathological attributes often associated with systemic conditions. This report presents a case of a 45-year-old male with no prior health issues who exhibits both clinical and pathological hallmarks of NUD without any concurrent systemic illness. This singular case illuminates the intricate aspects of NUD, emphasizing the necessity for accurate diagnostic methods and effective treatment strategies.

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.

Quality of Life with Neutrophilic Dermatoses

Neutrophilic dermatoses (NDs) encompass a wide range of cutaneous and extracutaneous manifestations, many of which impair quality of life (QoL) and are difficult to treat. Although NDs are transient and mild, others are chronic, severely debilitating conditions with profound impacts on QoL, including pain, mental health, occupational limitations, and sexual health implications. Current literature lacks attention to these unique care challenges to the ND patient population. The authors aim to summarize what is currently known about QoL in NDs and identify which diseases would benefit from additional research and disease-specific QoL assessment.

Neutrophilic Urticarial Dermatosis

Neutrophilic urticarial dermatosis (NUD) is a rare form of dermatosis that is poorly understood. It was first described by Kieffer and colleagues as an urticarial eruption that is histopathologically characterized by a perivascular and interstitial neutrophilic infiltrate with intense leukocytoclasia and without vasculitis or dermal edema. NUD clinically presents as a chronic or recurrent eruption that consists of nonpruritic macules, papules, or plaques that are pink to reddish and that resolve within 24 hours without residual pigmentation. NUD is often associated with systemic diseases such as Schnitzler syndrome, lupus erythematosus, adult-onset Still's disease, and cryopyrin-associated periodic syndromes.

Pediatric erythema ab igne: clinical aspects and diagnostic issues

Erythema ab igne is a dermatological condition resulting from repeated low-grade heat exposure (below the burning point), which can variably manifest with reticulated erythema and skin hyperpigmentation. Not infrequently, the cause of such a skin disorder is not immediately evident or reported by patients, especially if these are children. Compared to adults, erythema ab igne is rare in children and, if the general practitioners and pediatricians are not aware of this disorder, pediatric patients are often addressed to rheumatologists and/or undergo useless immunological investigations. Here, we performed a systematic case-based review, which finally included 32 cases of pediatric erythema ab igne (in addition to our new clinical report), and discussed the main clinical aspects and issues of this clinical entity in children. In detail, similarities of erythema ab igne with livedo reticularis and/or vasculitis-related rashes sometimes can lead to perform a panel of immunological investigations, which could be avoided. Indeed, our analysis emphasizes the importance of a careful and complete patient's anamnesis, including active questioning about the potential exposure to any physical agents (including heat sources) that may cause dermatological lesions. We also highlight some peculiarities in terms of location and heat injury in children developing erythema ab igne, based on the presence or absence of comorbidities.

CONCLUSION

The occurrence of erythema ab igne in children (and especially in adolescents) is likely to increase in the next years because of the greater and sometimes inappropriate use of technological devices. Physicians should be aware of this condition in order to prevent patients from useless investigations, especially in the differential diagnosis of rheumatic disorders. A careful and complete patient's history with active questioning about the potential exposure to heating source is often decisive to diagnose erythema ab igne.

WHAT IS KNOWN

• Erythema ab igne is a dermatological condition which is mainly described in adults exposed to heating source at the workplace.

WHAT IS NEW

• The occurrence of erythema ab igne in children is likely to increase in the next years because of the greater and sometimes inappropriate use of technological devices. • Erythema ab igne in children can be classified in two main categories, based on the presence or absence of comorbidity. • A careful and complete anamnesis (including the active questioning about potential exposure to any heating source) is the mainstay for diagnosing erythema ab igne in children.

Urticaria: A Narrative Overview of Differential Diagnosis

Urticaria is an inflammatory skin disorder that may occur in isolation or associated with angioedema and/or anaphylaxis. Clinically, it is characterized by the presence of smooth, erythematous or blanching, itchy swelling, called wheals or hives, which greatly vary in size and shape and last less than 24 h before fading to leave normal skin. Urticaria is the consequence of mast-cell degranulation that can be caused by immunological or non-immunological mechanisms. From a clinical point of view, many skin conditions can mimic urticaria and their recognition is mandatory for a correct management and therapeutic approach. We have reviewed all of the main relevant studies which addressed differential diagnosis of urticarial, published until December 2022. The National Library of Medicine PubMed database was used for the electronic research. The present review offers a clinical narrative overview, based on the available literature, of the principal skin disorders that can be misdiagnosed as urticaria (mainly autoinflammatory or autoimmune disorders, drug-induced reactions, and hyperproliferative diseases). The aim of this review is to provide clinicians a useful tool for correctly suspecting and identifying all of these conditions.

Current and future management of chronic spontaneous urticaria and chronic inducible urticaria

Background: Chronic urticaria (CU), characterized by ≥6 weeks of intense pruritus, remains a debilitating condition for patients. New and safe treatments are needed to manage CU recalcitrant to standard therapy. Objective: A review of the current literature of standard and novel therapeutics in the management of CU was conducted. Methods: A literature search via a medical literature data base and clinical trial data base was conducted to identify treatment options for CU and current clinical trials. Results: Second-generation antihistamines, omalizumab, and cyclosporine remain the most proven therapeutic options for CU. Dupilumab, mepolizumab, benralizumab, tezepelumab, and CDX-0159 are all undergoing clinical trials for CU. Although ligelizumab demonstrated initial promising results, a phase III study was discontinued due to a nonsuperior clinical impact compared with omalizumab. Conclusion: Novel therapies are needed for the treatment of recalcitrant CU. With a deeper understanding of the pathophysiology of CU, promising therapeutics are in clinical trials for CU.

Clinical Presentation of Schnitzler's Syndrome: A Rare Autoimmune Disease

Schnitzler's Syndrome (SS) is a rare late-onset acquired autoinflammatory disorder which consists of chronic urticaria associated with a monoclonal IgM-kappa gammopathy, arthralgias, skeletal hyperostosis, lymphadenopathy, and recurrent constitutional symptoms. The average age of diagnosis is 51 years with a slight male predominance with a male to female ratio of 1.6. Diagnosis of SS requires the presence of 2 major criteria including chronic urticaria and monoclonal IgM along with at least two of the following minor criteria: recurrent intermittent fevers, bone pain, arthralgias, elevated erythrocyte sedimentation rate (ESR), neutrophilic dermal infiltrate on skin biopsy, and leukocytosis or elevated C-reactive protein (CRP). Early diagnosis and clinical awareness are paramount in SS as it is associated with a 15-20% risk of lymphoproliferative malignancy. The median overall survival is 12.8 years. We present a case of a 39-year-old female with new onset urticaria associated with recurrent fevers and joint pain. Symptoms were refractory to steroids, and high dose antihistamines. Multi-disciplinary evaluation resulted in the ultimate diagnosis of Schnitzler's Syndrome. The patient was ultimately treated with canakinumab (Il-1 inhibitor), with near resolution of symptoms. This case demonstrates the importance of a broad differential diagnosis and maintaining a high clinical suspicion for rare diseases when presented with a complex form of an otherwise common condition.

Monoclonal gammopathies of clinical significance (MGCS): In pursuit of optimal treatment

Monoclonal gammopathy of clinical significance (MGCS) represents a new clinical entity referring to a myriad of pathological conditions associated with the monoclonal gammopathy of undetermined significance (MGUS). The establishment of MGCS expands our current understanding of the pathophysiology of a range of diseases, in which the M protein is often found. Aside from the kidney, the three main organ systems most affected by monoclonal gammopathy include the peripheral nervous system, skin, and eye. The optimal management of these MGUS-related conditions is not known yet due to the paucity of clinical data, the rarity of some syndromes, and limited awareness among healthcare professionals. Currently, two main treatment approaches exist. The first one resembles the now-established therapeutic strategy for monoclonal gammopathy of renal significance (MGRS), in which chemotherapy with anti-myeloma agents is used to target clonal lesion that is thought to be the culprit of the complex clinical presentation. The second approach includes various systemic immunomodulatory or immunosuppressive options, including intravenous immunoglobulins, corticosteroids, or biological agents. Although some conditions of the MGCS spectrum can be effectively managed with therapies aiming at the etiology or pathogenesis of the disease, evidence regarding other pathologies is severely limited to individual patient data from case reports or series. Future research should pursue filling the gap in knowledge and finding the optimal treatment for this novel clinical category.

Annular urticarial lesions

Annular urticarial configurations are often associated with acute and chronic urticaria. Such lesions may be short-lived, migratory, transient, pruritic, and resolving with no residual evidence, making the diagnosis of urticaria an obvious one. Annular urticarial lesions can be the presenting signs of various cutaneous and systemic diseases. The differentiation of urticarial lesions may be made by considering the duration of an individual lesion longer than 24 hours, with burning and pain sensation in the lesions or lack of pruritus; skin marks such as postinflammatory pigmentation or purpura after resolution of the lesions; associated scaling or vehiculation in the lesions; systemic symptoms such as arthralgia, fever or fatigue; and several abnormal laboratory findings. The main differential diagnoses of annular urticarial lesions include urticarial vasculitis, autoinflammatory syndromes, hypersensitivity reactions, and connective tissue diseases.

Neutrophilic dermatoses

Neutrophilic dermatoses (ND) are a group of inflammatory skin conditions characterized by a neutrophilic infiltrate on histopathology with no evidence of infection. ND are classified based upon the localization of neutrophils within the skin and clinical features. Recent findings suggest that ND are due to two main mechanisms: i) a polyclonal hereditary activation of the innate immune system (polygenic or monogenic); or ii) a clonal somatic activation of myeloid cells such as encountered in myelodysplastic syndrome or VEXAS syndrome. ND belong to internal medicine as a great number of patients with ND suffer from an underlying condition (such as hematological malignancy, inflammatory bowel disease, auto-immune and auto-inflammatory diseases). ND are diagnoses of exclusion and physicians should always consider differential diagnoses, particularly skin infections. Here, we review the pathophysiology and classification of the main ND (i.e., subcorneal pustular dermatosis (Sneddon-Wilkinson Disease) and Intercellular IgA dermatoses, aseptic pustulosis of the folds, Sweet syndrome, neutrophilic eccrine hidradenitis, pyoderma gangrenosum, erythema elevatum diutinum, neutrophilic urticarial dermatosis and neutrophilic panniculitis), their clinical and histopathological features, and we highlight the investigations that are useful to identify ND-associated diseases and to exclude the differential diagnoses.

Urticaria and angioedema in children and adolescents: diagnostic challenge

Urticaria diagnosis may be challenging in children since it can be triggered or related to numerous conditions. In this paper, we reviewed the main aspects regarding the diagnosis of urticaria in the pediatric population. Acute urticaria is often due to viral infections. However, other culprits, including foods, insect stings, drugs, contrast media, vaccination, latex, and medical diseases, may account for acute patterns. Laboratory tests and confirmatory allergy tests should be individualized and guided by history. Chronic urticaria (CU) is defined when hives and/or angioedema last for more than 6 weeks. The most common type of chronic urticaria in children is chronic spontaneous urticaria (CSU). Chronic inducible urticaria (CindU) is less common but is important to diagnose in order to manage appropriately and reduce the risk of severe reactions. Inducible forms in children are often diagnosed with specific provocation tests similar to the tests used in adults. Given that chronic urticaria could rarely be a presentation of vasculitis, systemic-onset juvenile idiopathic arthritis, or auto-inflammatory syndromes, it is important to rule out these conditions. It is crucial to differentiate cases of chronic urticaria from mastocytosis and Bradykinin-mediated angioedema, given that treatment may differ. The management of chronic urticaria in children has improved over the last decade because of the development of both clear management guidelines and new effective drugs. It is crucial to increase awareness for appropriate diagnosis and new available treatment to improve the management of chronic urticaria in children.

Urticarial vasculitis: Clinical and laboratory findings with a particular emphasis on differential diagnosis

Urticarial vasculitis (UV) is a rare cutaneous vasculitis of small vessels characterized by recurrent episodes of wheal-like lesions that tend to last more than 24 hours, healing with a residual ecchymotic postinflammatory hyperpigmentation. The histopathologic pattern of UV is that of leukocytoclastic vasculitis, consisting of fibrinoid necrosis of dermal vessels' walls and neutrophil-rich perivascular inflammatory infiltrates. Although its etiopahogenesis remains still undefined, UV is now regarded as an immune complex-driven disease with activation of the complement cascade, leading to exaggerated production of anaphylatoxins that are responsible for neutrophil recruitment and activation. This condition can be categorized into 2 main entities according to serum complement levels: normocomplementemic UV and hypocomplementemic UV, the latter being associated with circulating anti-C1q autoantibodies and possible extracutaneous manifestations. Systemic multiorgan involvement may be seen particularly in syndromic hypocomplementemic UV, also known as McDuffie syndrome. This review summarizes the clinicopathological and laboratory features as well as the underlying pathophysiological mechanisms of UV. A focus on its main differential diagnoses is provided, that is, chronic spontaneous urticaria, bullous pemphigoid, IgA (Henoch-Schönlein purpura) and IgM/IgG immune complex vasculitis, lupus erythematous tumidus, Wells syndrome, erythema multiforme, cutaneous mastocytosis, cryopyrin-associated periodic syndromes, and coronavirus disease 2019-associated and anti-severe acute respiratory syndrome coronavirus 2-vaccine-associated urticarial eruptions.

Diagnosis of Sweet's syndrome in otolaryngology

Sweet's syndrome (acute febrile neutrophilic dermatosis) consists of acute onset of painful cutaneous erythematous lesions, mostly found in the upper extremities followed by the head and neck region, particularly in patients with underlying malignancies. We describe the case of a woman in her mid-30s, who was treated for acute myeloid leukaemia and presented with a severe painful and progressive erythematous lesion of the retroauricular skin. Clinical features, laboratory tests, blood cultures and histological biopsy yielded a diagnosis of Sweet's syndrome. The treatment consisted of oral and topical corticosteroids and her signs and symptoms resolved within 1 week. Although Sweet's syndrome is uncommon, awareness among otolaryngologists is crucial to ensure a prompt diagnosis, cure and referral to an oncologist (if not already involved) for patients with Sweet's syndrome in the head and neck area.

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.

Clinical Phenotypes of Adult-Onset Still's Disease: New Insights from Pathophysiology and Literature Findings

Adult-onset Still's disease (AOSD) is a non-familial, polygenic systemic autoinflammatory disorder. It is traditionally characterized by four cardinal manifestations-spiking fever, an evanescent salmon-pink maculopapular rash, arthralgia or arthritis and a white-blood-cell count (WBC) ≥ 10,000/mm³, mainly neutrophilic polymorphonuclear cells (PMNs)-but many other manifestations and complications can be associated, making clinical expression very heterogeneous and diagnosis sometimes difficult. The AOSD course can be diverse and is currently impossible to predict. Several clinical phenotypes have been described, either on the basis of the evolution of symptoms over time (monocyclic, polycyclic and chronic evolution) or according to dominant clinical evolution (systemic and arthritis subtypes). However, these patterns are mainly based on case series and not on robust epidemiological studies. Furthermore, they have mainly been established a long time ago, before the era of the biological treatments. Thus, based on our personal experience and on recent advances in the understanding of disease pathogenesis, it appears interesting to reshuffle AOSD phenotypes, emphasizing the continuum between AOSD profiles and other systemic autoinflammatory disorders, eventually proposing a research agenda.

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.

Research Supporting a Pilot Study of Metronomic Dapsone during Glioblastoma Chemoirradiation

This short note presents previous research data supporting a pilot study of metronomic dapsone during the entire course of glioblastoma treatment. The reviewed data indicate that neutrophils are an integral part of human glioblastoma pathophysiology, contributing to or facilitating glioblastoma growth and treatment resistance. Neutrophils collect within glioblastoma by chemotaxis along several chemokine/cytokine gradients, prominently among which is interleukin-8. Old data from dermatology research has shown that the old and inexpensive generic drug dapsone inhibits neutrophils' chemotaxis along interleukin-8 gradients. It is on that basis that dapsone is used to treat neutrophilic dermatoses, for example, dermatitis herpetiformis, bullous pemphigoid, erlotinib-related rash, and others. The hypothesis of this paper is that dapsone will reduce glioblastomas' neutrophil accumulations by the same mechanisms by which it reduces dermal neutrophil accumulations in the neutrophilic dermatoses. Dapsone would thereby reduce neutrophils' contributions to glioblastoma growth. Dapsone is not an ideal drug, however. It generates methemoglobinemia that occasionally is symptomatic. This generation is reduced by concomitant use of the antacid drug cimetidine. Given the uniform lethality of glioblastoma as of 2020, the risks of dapsone 100 mg twice daily and cimetidine 400 mg twice daily is low enough to warrant a judicious pilot study.

Lupus erythematosus: Significance of dermatologic findings

Herein, the different skin manifestations in patients with lupus erythematosus are reviewed, and their diagnostic, pathogenic and prognostic relevance are discussed, as well as their impact on therapeutic choices. The so-called specific lesions of LE result from an autoimmune pathomechanism and they allow diagnosis of LE by simple clinicopathological correlation since the findings are characteristic. They include the classic acute, subacute and chronic variants, characterised microscopically by interface dermatitis; the dermal variants of lupus, such as tumid lupus, displaying dermal perivascular lymphocytic infiltrate with mucin deposition under the microscope, and lupus profundus, in which lymphocytic lobular panniculitis progressing to hyaline fibrosis is found. Antimalarials are the treatment of choice for patients with specific LE lesions. The presence of some dermatological signs is the result of thrombotic vasculopathy. Their recognition allows the identification of lupus patients at increased cardiovascular risk and with a worse overall prognosis. Those signs include reticulated erythema on the tip of the toes, splinter hemorrhages, atrophie blanche, pseudo-Degos lesions, racemosa-type livedo, anetoderma, ulceration and necrosis. Those clinical manifestations, often subtle, must be recognised, and if present, patients should be treated with antiplatelet drugs. Finally, neutrophilic cutaneous lupus erythematosus includes a few entities that suggest that autoinflammatory mechanisms might play a key role in certain lupus manifestations. Among those entities, it is very important to diagnose neutrophilic urticarial dermatosis, which can mimic a classic lupus flare, because it is characterised by rash with joint pain, but immunosuppressants are not helpful. Dapsone is the treatment of choice.

Skin Biopsy in Chronic Urticaria: When and Where and What to Look for?

Chronic urticaria is a relatively common condition in dermatology and is usually diagnosed on clinical grounds. Skin biopsy, however, may be indicated in certain cases to confirm diagnosis and rule out other conditions that can cause hive-like rashes. We review histopathologic findings seen in both chronic urticaria and other entities in the differential diagnosis. We then propose an algorithm of indications for skin biopsy in patients with hive-like rashes and suggest possible diagnoses based on the histopathologic findings.

Refractory Urticaria with Raised Antistreptolysin O (ASO) Titer: An Intriguing Case of Adult-Onset Still's Disease

Patient: Female, 26-year-old

Final Diagnosis: Adult-onset Still’s disease

Symptoms: Fever • urticaria

Medication: —

Clinical Procedure: —

Specialty: Dermatology • Rheumatology

Neutrophilic dermatoses with unusual and atypical presentations

Neutrophilic dermatoses (NDs) are a group of reactive, noninfectious autoinflammatory diseases characterized by (1) infiltration of the epidermis, dermis, and or/hypodermis by neutrophils; (2) their association with distinct diseases (eg, hematologic malignancy and chronic inflammatory diseases); (3) potential extracutaneous involvement; and (4) response to anti-inflammatory drugs, such as corticosteroids, dapsone, colchicine, and novel biologic therapies, such as the anti-interleukin-1 blockade. Although distinct NDs have been described, transitional forms with overlapping features are often identified. These justify a simplified classification of NDs with three major forms: superficial (epidermal or pustular) NDs, dermal (en plaques) NDs, and deep NDs. We review selected or novel variants of NDs, including subcorneal pustular dermatosis, the group of immunoglobulin A neutrophilic dermatoses, amicrobial pustular dermatosis of the folds, and neutrophilic urticarial dermatosis, as well as atypical forms of Sweet syndrome and pyoderma gangrenosum closely mimicking severe infectious diseases. Knowledge of these variants is essential for proper diagnosis, adequate management, and avoidance of a dangerous escalation of therapy, such as unnecessary immunosuppression or extensive surgery.

Scarring alopecia in chronic cutaneous lupus erythematosus with neutrophils: A new scenario with therapeutic connotations

The relationship between autoinflammatory and autoimmune conditions has been demonstrated in recent decades. Several autoimmune conditions exhibit an autoinflammatory component, which can manifest in various ways. Neutrophilic dermatosis in the context of lupus erythematosus (LE) is one example. Otherwise, neutrophils are rare in LE, except for the bullous variant and nonbullous neutrophilic LE. In this paper, we describe a case of scarring alopecia due to LE that stopped responding to a treatment that had been effective for years. The biopsy specimen demonstrated the presence of neutrophils in the inflammatory infiltrate. A treatment with dapsone was prescribed and yielded rapid improvement. This first case of scarring alopecia in the context of nonbullous neutrophilic LE emphasizes the importance of the infiltrate in determining the optimal therapeutic choice.

Somatic Mosaic NLRP3 Mutations and Inflammasome Activation in Late-Onset Chronic Urticaria

Chronic urticaria is a common skin disorder with heterogeneous causes. In the absence of physical triggers, chronic urticarial rash is called idiopathic or spontaneous. The objective of this study was to identify the molecular and cellular bases of a disease condition displayed by two unrelated patients aged over 60 years who presented for two decades with a chronic urticaria resistant to standard therapy that occurred in the context of systemic inflammation not triggered by cold. In both patients, a targeted sequencing approach using a next generation technology identified somatic mosaic mutations in NLRP3, a gene encoding a key inflammasome component. The study of several of both patients' cell types showed that, despite the late onset of the disease, NLRP3 mutations were not found to be restricted to myelomonocytic cells. Rather, the data obtained strongly suggested that the mutational event occurred very early, during embryonic development. As shown by functional studies, the identified mutations-an in-frame deletion and a recurrent NLRP3 missense mutation-have a gain-of-function effect on NLRP3-inflammasome activation. Consistently, a complete remission was obtained in both patients with anti-IL-1 receptor antagonists. This study unveils that in late-onset chronic urticaria, the search for autoinflammatory markers and somatic mosaic NLRP3 mutations may have important diagnostic and therapeutic consequences.