From acute febrile neutrophilic dermatosis to neutrophilic disease: forty years of clinical research

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.

The Neutrophilic Dermatoses, or the Cutaneous Expressions of Neutrophilic Inflammation

Acute febrile neutrophilic dermatosis, or Sweet syndrome, has been described in 1964 and is now considered as a prototypical condition of the group of the neutrophilic dermatoses. Since this time, many clinical conditions have been included in this group and a clinical-pathological classification in 3 subgroups has been proposed. Neutrophilic infiltrates can localize in all internal organs. This defines the neutrophilic disease, which induces difficult diagnostic and therapeutic problems. Autoinflammation is the main pathophysiological mechanism of the neutrophilic dermatoses. There is a special link between myeloid malignancies (leukemia and myelodysplasia) and the neutrophilic dermatoses.

Postoperative and Peristomal Pyoderma Gangrenosum: Subtypes of Pyoderma Gangrenosum

Postoperative pyoderma gangrenosum and peristomal pyoderma gangrenosum are 2 subtypes of pyoderma gangrenosum. The diagnosis is made as a clinicopathologic correlation when assessing a rapidly progressing ulcer with irregular and undermined borders following a surgical procedure, trauma, or the creation of a stoma. Familiarity with the associated risk factors and distinguishing features of these disorders can facilitate prompt recognition, proper diagnosis, and the initiation of treatment. Management usually involves the use of corticosteroids and steroid-sparing agents as immunomodulators to shift the inflammatory neutrophilic dermatoses to chronic noninflammatory wounds and eventual healing.

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.

Neutrophilic dermatosis and hidradenitis suppurativa in patients with Behçet's disease: A neutrophilic disease in the spectrum of autoinflammatory syndromes

BACKGROUND

Association of neutrophilic dermatosis (ND), hidradenitis suppurativa (HS) and Behçet's disease (BD) and shared efficacy of TNFα axis blockade suggests common physiopathology.

OBJECTIVES

To investigate the clinical features and therapeutic response of ND and HS associated with BD.

METHODS

We identified 20 patients with ND or HS associated with BD among 1462 patients with BD.

RESULTS

We analysed 20 (1.4%) patients diagnosed with ND or HS associated with BD: 13 HS, 6 pyoderma gangrenosum (PG), and 1 SAPHO. Our 6 PG cases over 1462 BD patients accounts for 400/100 000 prevalence. Thirteen had bipolar aphthosis, 6 vascular, 5 neurologic, and 4 ocular involvements. All PG occurred on limbs and had typical histology with constant dermal neutrophilic infiltrate. All HS had the classical axillary-mammary phenotype. Sixty-nine percent (69%) of HS were Hurley 1 stage. Treatment consisted mainly in colchicine (n = 20), glucocorticoids (n = 12), and anti-TNFα (n = 9). Interesting results with complete or partial responses were obtained with anti-TNFα (9 cases), ustekinumab (3 cases) and tocilizumab (1 case) to treat refractory ND or HS associated with BD.

CONCLUSION

PG seems overrepresented in patients with BD. Biotherapies such as anti-TNFα, ustekinumab and tocilizumab appear to be promising to treat refractory ND or HS associated with BD.

Annular neutrophilic dermatoses

Neutrophilic dermatoses (NDs) constitute a group of diseases characterized by sterile neutrophilic infiltrations. Many NDs usually present with infiltrated erythematous plaques, nodules, urticarial plaques, or pustules. Lesions may show variability, and atypical presentations may develop among NDs. Annular lesions have been reported in many NDs and may lead to diagnostic problems. Clinical features and histopathologic findings such as localization of the neutrophilic infiltrate, existence of other cell types, and absence of true vasculitis may be helpful to distinguish NDs. Some of these NDs are associated with infections, inflammatory diseases, and malignancies. In most NDs, systemic steroids and dapsone are very effective and usually first choices. Colchicine, antimicrobials such as doxycycline, tetracycline, and sulfapyridine, and other immunosuppressants such as cyclosporin, methotrexate, and mycophenolate mofetil have been used successfully in treating many NDs. Tumor necrosis factor α inhibitors have also been used successfully in treating many NDs. Janus kinase inhibitors are effective in CANDLE (chronic atypical neutrophilic dermatosis with lipodystrophy and elevated temperature) syndrome, anakinra in neutrophilic urticarial dermatosis, and intravenous immunoglobulin in resistant pyoderma gangrenosum. We discuss the diagnosis and management of NDs that may present with annular lesions.

From the Deep: Overlap of Neutrophilic Dermatoses Disorders Associated With Acute Myeloid Leukemia

We report the case of a man in his 50s with refractory acute myelomonocytic leukaemia (AML) who presented with neck swelling, fever, and elevated levels of C-reactive protein (CPR) after venous punctures. An infected haematoma was presumed, but the patient showed no signs of improvement under broad-range antibiotics, and microbiological results were negative. The subsequent development of a rapidly evolving erythematous-violaceous plaque around a site that had previously punctured on the extensor surface of the right arm prompted us to reconsider the clinical setting as a whole and consider the hypothesis of deep neutrophilic dermatosis (ND) associated with haematologic malignancy. A biopsy of the arm lesion showed an aseptic neutrophilic infiltrate, confirming this diagnosis. The patient was initially treated with high-dose intravenous corticosteroids, resulting in a dramatic improvement of the skin lesions.

Dermatological manifestations of hematologic neoplasms. Part II: nonspecific skin lesions/paraneoplastic diseases

Cutaneous manifestations occur in the course of hematologic malignancies and precede, accompany or occur late in relation to the diagnosis. They result from paraneoplastic phenomena, tumor infiltrations, immunosuppression resulting from the hematologic disease itself or its treatment. The dermatologist must be aware of these conditions that may be helpful both in the diagnosis of the underlying disease and in reducing patient morbidity. This review (part II) addresses the paraneoplastic dermatological changes associated with systemic hematologic malignancies.

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.

Neutrophilic Dermatoses in a Clinical Practice of Wound Care Professionals

ABSTRACT

Diagnosing and treating neutrophilic dermatoses (NDs) in clinical practice can be challenging because of various presentations and stubborn treatment responses. Establishing a diagnosis is necessary, though, because many NDs are associated with underlying conditions, including malignancy. In this article, the authors provide information about Sweet syndrome, pyoderma gangrenosum, and other NDs and describe their clinical presentation, pathophysiology, diagnostic criteria, and associated conditions. The authors also present a case report describing the coexistence of two NDs and hidradenitis suppurativa in one patient and review the treatment modalities for those conditions.

Pyoderma gangrenosum with pulmonary involvement: a pulmonary special report and literature review

INTRODUCTION

Pyoderma gangrenosum (PG) is the prototypical neutrophilic dermatosis, commonly associated with inflammatory bowel disease, with pulmonary involvement being the commonest extracutaneous manifestation. PG with tracheobronchial involvement may present as upper airway obstruction and can be life-threatening.

AREAS COVERED

To evaluate the clinical characteristics and predictors of PG with pulmonary involvement, we reported a case of PG with tracheobronchial involvement in China, and performed a literature retrieval on PG with pulmonary involvement. Demographic data, clinical presentations, underlying diseases, radiological and histopathological findings, treatments, and clinical outcomes were collected and subjected to statistical analysis. Forty-seven cases (including ours) were identified. Diseases associated with PG with pulmonary involvement were similar. Clinical presentation of PG with pulmonary involvement was non-specific, with cough and dyspnea being the most common clinical symptoms, and pulmonary infiltrates and cavitation being the most common radiological signs. Further univariate analysis suggested stridor and young age (p < 0.01) may be predictors of tracheobronchial involvement in PG.

EXPERT OPINION

PG with tracheobronchial involvement can be life-threatening, with young age and stridor being possible predictors. Therefore, prompt airway assessment and management are required in younger patients with PG with pulmonary involvement presenting with stridor.

Sweet's Syndrome: An Update

Sweet's syndrome is a serious dermatological disorder characterized by a rapid onset of tender plaques or nodules, fever, joint pain, headache, and oral and genital lesions. According to the clinical features and underlying causes, Sweet's syndrome is divided into three categories, i.e., classical (or idiopathic), malignancy-associated Sweet's syndrome, and drug-induced Sweet's syndrome. It is multifactorial in etiology, and the exact cause is still undetermined. The diagnosis can be confirmed by the routine histopathologic evaluation of skin biopsy from the lesions. The first-line treatment options are topical and systemic steroids. Multiple databases, like Medline/PubMed, Scopus, and Google, were used to identify resources for this literature review. The relevant information was collected from various case reports, case series, reviews, meta-analyses, and large clinical trials reporting clinical description, etiology, diagnosis, and management of Sweet's syndrome. This narrative review aimed to discuss recent understandings related to Sweet's syndrome, both in terms of clinical presentation and management approach.

Cranial aseptic osteomyelitis associated with pyoderma gangrenosum

Neutrophilic dermatoses include a heterogeneous group of entities. Uncommonly, they can accumulate aseptic neutrophilic abscesses in other tissues in addition to the skin. A 34-year-old female complained of a headache which was unresponsive to usual drugs. A TAC revealed an osteolytic lesion in the right parietal bone. The biopsy showed osteomyelitis. One year later, pyoderma gangrenosum appeared in the anterior aspect of both legs. The headache and the cutaneous lesions disappeared after treatment with oral prednisone. The bone involvement in the background of neutrophilic dermatoses is exceptional. Usually, it involves children in the context of chronic recurrent multiple osteomyelitis (CRMO). Only two cases have been described in adults. One of them was a 26-year-old woman who had had CRMO since childhood, and the other one in contiguity with the cutaneous lesions of pyoderma gangrenosum.

Evaluation of neutrophil extracellular trap deregulated formation in pyoderma gangrenosum

Pyoderma gangrenosum (PG) is a neutrophilic dermatose (ND) characterized by a dense neutrophilic infiltrate in the affected tissue. Neutrophil extracellular traps (NETs) are web-like structures released by neutrophils and composed of cytosolic and granule proteins assembled on a scaffold of decondensed chromatin. Very little is known about the role of NETosis in PG. Here, we assessed the possible implication of NETosis in the pathogenesis of PG by investigating the NETosis in the ulcers of 26 PG patients. We demonstrated that neutrophils in the PG skin lesions undergo an aberrant level of NETosis in 100% of the analysed cases (N = 26). All control and abscess biopsies were instead negative for the NETosis. In addition, neutrophils from peripheral blood of PG patients showed a significantly higher rate of spontaneous, but not induced, NETosis. Overall, this study suggests that the NETosis may contribute to systemic inflammation and tissue destruction in PG, thus representing a possible novel therapeutic target.

Cranial aseptic osteomyelitis associated with pyoderma gangrenosum

Neutrophilic dermatoses include a heterogeneous group of entities. Uncommonly, they can accumulate aseptic neutrophilic abscesses in other tissues in addition to the skin. A 34-year-old female complained of a headache which was unresponsive to usual drugs. A TAC revealed an osteolytic lesion in the right parietal bone. The biopsy showed osteomyelitis. One year later, pyoderma gangrenosum appeared in the anterior aspect of both legs. The headache and the cutaneous lesions disappeared after treatment with oral prednisone. The bone involvement in the background of neutrophilic dermatoses is exceptional. Usually, it involves children in the context of chronic recurrent multiple osteomyelitis (CRMO). Only two cases have been described in adults. One of them was a 26-year-old woman who had had CRMO since childhood, and the other one in contiguity with the cutaneous lesions of pyoderma gangrenosum.

Dermatological Manifestations in Inflammatory Bowel Diseases

Inflammatory bowel diseases (IBDs) may be associated with extra-intestinal manifestations. Among these, mucocutaneous manifestations are relatively frequent, often difficult to diagnose and treat, and may complicate the course of the underlying disease. In the present review, a summary of the most relevant literature on the dermatologic manifestations occurring in patients with inflammatory bowel diseases has been reviewed. The following dermatological manifestations associated with IBDs have been identified: (i) specific manifestations with the same histological features of the underlying IBD (occurring only in Crohn's disease); (ii) cutaneous disorders associated with IBDs (such as aphthous stomatitis, erythema nodosum, psoriasis, epidermolysis bullosa acquisita); (iii) reactive mucocutaneous manifestations of IBDs (such as pyoderma gangrenosum, Sweet's syndrome, bowel-associated dermatosis-arthritis syndrome, aseptic abscess ulcers, pyodermatitis-pyostomatitis vegetans, etc.); (iv) mucocutaneous conditions secondary to treatment (including injection site reactions, infusion reactions, paradoxical reactions, eczematous and psoriasis-like reactions, cutaneous infections, and cutaneous malignancies); (v) manifestations due to nutritional malabsorption (such as stomatitis, glossitis, angular cheilitis, pellagra, scurvy, purpura, acrodermatitis enteropathica, phrynoderma, seborrheic-type dermatitis, hair and nail abnormalities). An accurate dermatological examination is essential in all IBD patients, especially in candidates to biologic therapies, in whom drug-induced cutaneous reactions may assume marked clinical relevance.

Immune-Mediated Dermatoses in Patients with Haematological Malignancies: A Comprehensive Review

Haematological malignancies induce important alterations of the immune system, which account for the high frequency of autoimmune complications observed in patients. Cutaneous immune-mediated diseases associated with haematological malignancies encompass a heterogeneous group of dermatoses, including, among others, neutrophilic and eosinophilic dermatoses, autoantibody-mediated skin diseases, vasculitis and granulomatous dermatoses. Some of these diseases, such as paraneoplastic pemphigus, are associated with an increased risk of death; others, such as eosinophilic dermatoses of haematological malignancies, run a benign clinical course but portend a significant negative impairment on a patient’s quality of life. In rare cases, the skin eruption reflects immunological alterations associated with an unfavourable prognosis of the associated haematological disorder. Therapeutic management of immune-mediated skin diseases in patients with haematological malignancies is often challenging. Systemic corticosteroids and immunosuppressive drugs are considered frontline therapies but may considerably augment the risk of serious infections. Indeed, developing a specific targeted therapeutic approach is of crucial importance for this particularly fragile patient population. This review provides an up-to-date overview on the immune-mediated skin diseases most frequently encountered by patients with onco-haematological disorders, discussing new pathogenic advances and therapeutic options on the horizon.

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.

Behçet disease (BD) and BD-like clinical phenotypes: NF-κB pathway in mucosal ulcerating diseases

Behçet's disease (BD) is a heterogeneous multi-organ disorder in search of a unified pathophysiological theory and classification. The disease frequently has overlapping features resembling other disease clusters, such as vasculitides, spondyloarthritides and thrombophilias with similar genetic risk variants, namely HLA-B*51, ERAP1, IL-10, IL-23R. Many of the BD manifestations, such as unprovoked recurrent episodes of inflammation and increased expression of IL-1, IL-6 and TNFα, overlap with those of the hereditary monogenic autoinflammatory syndromes, positioning BD at the crossroads between autoimmune and autoinflammatory syndromes. BD-like disease associates with various inborn errors of immunity, including familial Mediterranean fever, conditions related to dysregulated NF-κB activation (eg TNFAIP3, NFKB1, OTULIN, RELA, IKBKG) and either constitutional trisomy 8 or acquired trisomy 8 in myelodysplastic syndromes. We review here the recent advances in the immunopathology of BD, BD-like diseases and the NF-κB pathway suggesting new elements in the elusive BD etiopathogenesis.

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.

Subcorneal pustular dermatosis: Comprehensive review and report of a case presenting during pregnancy

Subcorneal pustular dermatosis (SPD), also known as Sneddon-Wilkinson disease, is a rare, relapsing, sterile pustular eruption of unknown etiology that develops most commonly in middle-aged or mature women. This article reviews the presentation, associations, and management of the condition and highlights advances in pathophysiology. Onset of SPD during pregnancy has not been reported. Herein, we report a case of SPD that developed during pregnancy. The patient was treated with dapsone without complications for her or the fetus. An association between T helper (Th) 17 and Th2 environments in the development of SPD has been advocated. Pregnancy is characterized by a predominance of Th2 responses and increased interleukin-17 levels and thus may favor the development of the condition.

Erythema elevatum et diutinum as a systemic disease

Erythema elevatum et diutinum (EED) is a rare, chronic dermatosis. It has been associated with extracutaneous findings, including arthralgias, scleritis, panuveitis, peripheral ulcerative keratitis, oral and penile ulcers, and neuropathy. Additionally, EED is connected with various systemic diseases, including HIV, IgA paraproteinemia, myelomas, neutrophilic dermatoses, and inflammatory bowel diseases. The presence of such extracutaneous manifestations in EED patients suggests that EED may be a multiorgan entity. Extracutaneous manifestations in EED may involve deposition of circulating immune complexes; thus, patients with EED should be evaluated for systemic manifestations to ensure targeted management.

Neutrophilic Dermatoses and Their Implication in Pathophysiology of Asthma and Other Respiratory Comorbidities: A Narrative Review

Neutrophilic dermatoses (ND) are a polymorphous group of noncontagious dermatological disorders that share the common histological feature of a sterile cutaneous infiltration of mature neutrophils. Clinical manifestations can vary from nodules, pustules, and bulla to erosions and ulcerations. The etiopathogenesis of neutrophilic dermatoses has continuously evolved. Accumulating genetic, clinical, and histological evidence point to NDs being classified in the spectrum of autoinflammatory conditions. However, unlike the monogenic autoinflammatory syndromes where a clear multiple change in the inflammasome structure/function is demonstrated, NDs display several proinflammatory abnormalities, mainly driven by IL-1, IL-17, and tumor necrosis factor-alpha (TNF-a). Additionally, because of the frequent association with extracutaneous manifestations where neutrophils seem to play a crucial role, it was plausible also to consider NDs as a cutaneous presentation of a systemic neutrophilic condition. Neutrophilic dermatoses are more frequently recognized in association with respiratory disorders than by chance alone. The combination of the two, particularly in the context of their overlapping immune responses mediated primarily by neutrophils, raises the likelihood of a common neutrophilic systemic disease or an aberrant innate immunity disorder. Associated respiratory conditions can serve as a trigger or may develop or be exacerbated secondary to the uncontrolled skin disorder. Physicians should be aware of the possible pulmonary comorbidities and apply this knowledge in the three steps of patients' management, work-up, diagnosis, and treatment. In this review, we attempt to unravel the pathophysiological mechanisms of this association and also present some evidence for the role of targeted therapy in the treatment of both conditions.

Age-specific characteristics of neutrophilic dermatoses and neutrophilic diseases in children

BACKGROUND

Our suggested 'modern' concepts of 'neutrophilic dermatoses' (ND) and 'neutrophilic disease' were based on observations in adult patients and have not been studied in paediatric patients. Only a minority of ND occurs in children, and little is known about age-specific characteristics.

OBJECTIVES

To describe age-specific characteristics of ND in children and to study whether our suggested 'modern' classification of ND may be applied to children.

METHODS

We conducted a retrospective multicentre study in a French cohort of 27 paediatric patients diagnosed with pyoderma gangrenosum (PG) or Sweet's syndrome (SS).

RESULTS

Demographics and distribution of typical/atypical forms were similar in patients diagnosed with PG and SS. Atypical ND were more frequent in infants (90%), when compared to young children (60%) and adolescents (33%). Neutrophilic disease was observed in 17/27 patients and was most frequent in infants. Neutrophilic disease of the upper respiratory tract, as well as cardiac neutrophilic disease, was only observed in infants, whereas other locations were similarly found in infants, young children and adolescents. In infants and young children, ND were associated with a large spectrum of general diseases, whereas in adolescents associations were limited to inflammatory bowel disease and Behçet's disease.

CONCLUSIONS

Our study describes the concept of ND in paediatric patients and shows that they have some characteristics different from ND occurring in adults. ND occurring in infants can be associated with a large spectrum of general diseases. Occurrence of neutrophilic disease is frequent in children. Thus, ND occurring in young paediatric patients should incite clinicians to schedule complementary explorations in order to search for involvement of other organs and to rule out monogenetic autoinflammatory syndromes.

Neutrophilic Dermatoses Associated with Myeloid Malignancies

Neutrophilic dermatoses (ND) are a group of conditions characterized by an aseptic accumulation of polymorphonuclear leukocytes in the skin. Occurrence of ND in association with myeloid malignancies, mainly myelodysplastic syndrome and myelogenous acute leukemia, is not rare and is often associated with a poor prognosis. Recent findings have improved understanding of the pathophysiology of myeloid malignancy-associated ND. We review the clinical spectrum of myeloid malignancy-associated ND with an emphasis on recently identified mechanisms. Myeloid leukemia cells retain the potential for terminal differentiation into polymorphonuclear leukocytes in the skin. Many studies suggest a clonal link between myeloid malignancies and ND. Activation of autoinflammatory pathways (NOD-like receptor family pyrin domain-containing-3, Familial Mediterranean Fever Gene) in the clonal cells of myeloid disorders may also be involved in this setting.

Insights Into the Pathogenesis of Sweet's Syndrome

Sweet's syndrome, also known as Acute Febrile Neutrophilic Dermatosis, is a rare inflammatory condition. It is considered to be the prototype disease of neutrophilic dermatoses, and presents with acute onset dermal neutrophilic lesions, leukocytosis, and pyrexia. Several variants have been described both clinically and histopathologically. Classifications include classic Sweet's syndrome, malignancy associated, and drug induced. The cellular and molecular mechanisms involved in Sweet's syndrome have been difficult to elucidate due to the large variety of conditions leading to a common clinical presentation. The exact pathogenesis of Sweet's syndrome is unclear; however, new discoveries have shed light on the role of inflammatory signaling, disease induction, and relationship with malignancy. These findings include an improved understanding of inflammasome activation, malignant transformation into dermal infiltrating neutrophils, and genetic contributions. Continued investigations into effective treatments and targeted therapy will benefit patients and improve our molecular understanding of inflammatory diseases, including Sweet's syndrome.

Cutaneous Manifestations of ANCA-Associated Small Vessels Vasculitis

Skin lesions are frequent manifestations of underlying systemic conditions, including systemic autoimmune vasculitis. In particular, anti-neutrophil cytoplasmic antibodies (ANCA) are associated with distinct forms of vasculitis characterized by inflammatory cell infiltration of the walls of small and medium-sized vessels leading to vascular destruction and tissue necrosis. ANCA-associated vasculitis is rare and systemic diseases, which can be classified based on different distribution of vascular inflammation and presence or absence of granulomatosis and asthma. Despite their diversities, ANCA-associated vasculitis, namely microscopic polyangiitis, granulomatosis with polyangiitis and eosinophilic granulomatosis with polyangiitis, can all display a broad variety of cutaneous manifestations, which can appear during the course of the disease or even as first sign at the time of onset. Different skin manifestations might coexist in the same patient and occur in different occasions during the course of the vasculitis. Thus, a deep knowledge of the spectrum of skin lesions as part of ANCA-associated vasculitis is mandatory for a correct diagnostic process, whenever cutaneous vasculitis is suspected. Due to this broad variety of manifestations, the diagnosis of skin involvement in ANCA-associated vasculitis is very challenging and it must be supported by a detailed medical history, accurate physical examination, specific histopathological analysis of skin biopsy and the presence of ANCA serology. In this review, we focus on the cutaneous manifestations that can develop in the context of ANCA-associated vasculitis, detailing the clinical features, the histopathological aspects as well as the direct immunofluorescence studies for each of the three conditions. Moreover, we acknowledged the differential diagnoses that must be ruled out in the diagnostic process and the main therapeutic approaches available for treatment of ANCA-associated vasculitis.

Pyoderma gangrenosum-like ulcerations in granulomatosis with polyangiitis: two cases and literature review

Granulomatosis with polyangiitis (GPA) is a systemic necrotizing small vessel vasculitis associated with circulating anti-neutrophil cytoplasmic antibodies (ANCAs). Skin manifestations, mostly represented by palpable purpura, papulonodular lesions and livedo reticularis, are present in up to 50% of the cases. Ulcerations with undermined, raised erythematous-violaceous border resembling pyoderma gangrenosum (PG) have rarely been reported as skin involvement in GPA. The presence of circulating ANCAs with a cytoplasmic labelling pattern, the involvement of internal organs, particularly of the lung, and the absence on histology of a mainly neutrophilic infiltrate in early phases of the cutaneous lesions may be regarded as clues to rule out true PG and confirm the diagnosis of GPA skin ulcerations simulating PG. Herein, we describe two paradigmatic cases of such a unique presentation of GPA and a literature review focusing on clinicopathological features of GPA presenting with PG-like ulcerations in the skin has been provided. Moreover, referring to the scenario observed in these two cases, an easy-to-use working approach for the differential diagnosis between the two conditions has also been proposed.

Pyoderma gangrenosum: a review of pathogenesis and treatment

INTRODUCTION

Pyoderma gangrenosum (PG) is a complex neutrophilic dermatosis that can occur as an idiopathic disease, in association with systemic conditions such as inflammatory bowel disease, as part of an inherited inflammatory syndrome. It can be challenging to treat, as it occurs in a wide variety of clinical settings and there is a lack of a standardized treatment approach. The main limitations to treatment have been an incomplete understanding of the pathogenesis. However, recent advances have been made in understanding the pathogenesis of this condition, and PG is now considered an autoinflammatory disease process. Areas covered: This review discusses the newest studies that further define our understanding of this disease and the relevant literature on treatment options for pyoderma gangrenosum. Expert commentary: The presence of abnormal neutrophils and T-cells lead to immune dysregulation, leading to lesions of PG. Increased levels of inflammatory mediators including IL-1β, IL-8, IL-17, and TNF-α contribute to the development of the disease but there are still several unknown factors, including the trigger for immune dysregulation and additional contributory components of the immune system. We provide our approach to the management of PG lesions, which involves a multi-faceted approach including wound care, topical therapy, and systemic medications in most cases.

Aseptic lung and liver abscesses: a diagnostic challenge

A 67-year-old man known with systemic sarcoidosis was admitted to the department of internal medicine because of cough and chest pain for several weeks. Thoracic tomodensitometry demonstrated multiple pulmonary nodules. Biopsies revealed features compatible with abscesses. Cultures and serologic tests were negative and the patient was successfully treated with prednisone. Three years later, a thoraco-abdominal tomodensitometry showed a relapse in the lung and also the apparition of similar lesions in the liver. Blood test revealed elevated CRP level at 40 mg/L and mild cholestasis. Biopsies of the liver excluded neoplastic or infectious diseases and showed inflammatory granulation tissue with abscess formation. A diagnosis of sarcoidosis-associated aseptic abscesses syndrome was then made, which was successfully treated with corticosteroids.

Drug management of neutrophilic dermatoses

INTRODUCTION

Neutrophilic dermatoses are a heterogenous group of chronic, cutaneous inflammatory conditions characterized by the accumulation of neutrophils in the skin and by systemic inflammation. Neutrophilic dermatoses can be idiopathic or associated with other inflammatory or systemic diseases, including the group of the hereditary, autoinflammatory syndromes. Clinical management is challenging, due to limited clinical evidence and lack of clinical practice guidelines. Areas covered: This review provides an overview of current therapeutic management of the three prototypical neutrophilic dermatoses, aseptic pustulosis of the folds, Sweet syndrome and pyoderma gangrenosum. In addition, we describe innovative, pathogenesis-oriented treatment approaches, which are based on recent advances in the pathophysiology of neutrophilic dermatoses and autoinflammatory syndromes. The increasing role of the IL-1 cytokine family in initiating neutrophilic inflammation in both idiopathic and syndromic disease opened the way for the use of targeted biological treatment. Another promising treatment strategy is aimed at blocking downstream effector cytokines, such as IL12/23 and IL-17, involved in the autoinflammatory immune cascade. Expert commentary: In chronic-recurrent and syndromic cases of neutrophilic dermatoses, there is an unmet clinical need for long-term, continuous disease control. Future controlled clinical studies will optimize the use of targeted-biological agents in sequential or combination treatment strategies.

Sweet's Syndrome Arising in a Scar

Acute febrile neutrophilic dermatosis (Sweet's syndrome) is an uncommon inflammatory cutaneous disorder. It presents with lesions which are tender, erythematous, edematous papules and under histologic examination show dense neutrophilic infiltration of the dermis. These lesions are often accompanied by leukocytosis and fever. This paper reports a unique case of acute febrile neutrophilic dermatosis presenting as a Koebner response to a linear scar.

Hidradenitis Suppurativa Is Characterized by Dysregulation of the Th17:Treg Cell Axis, Which Is Corrected by Anti-TNF Therapy

Hidradenitis suppurativa (HS) is a chronic, inflammatory, and debilitating disease of hair follicles with 1-4% prevalence and high morbidity. There is a dearth of information on the pathogenesis and immune dysregulation underlying HS; therefore, we carried out a detailed analysis of skin-infiltrating T cells. Cells isolated from skin biopsy samples and blood from HS patients and healthy control subjects were analyzed by 16-parameter flow cytometry to provide detailed profiles of CD4 T-cell subsets. We observed substantial infiltration of inflammatory T cells with a striking T helper (Th) type 17-skewed cytokine profile in HS skin; these cells expressed the Th17 lineage marker CD161 and IL-17, as well as proinflammatory cytokines GM-CSF, IL-22, IFN-γ, and tumor necrosis factor. Regulatory T cells were also enriched in HS lesional skin; however, the ratio of Th17 to regulatory T cells was nonetheless highly dysregulated in favor of Th17 cells. In contrast, lesional skin from anti-tumor necrosis factor-treated HS patients who showed substantial clinical improvement exhibited a significant reduction in the frequency of Th17 cells and normalization of the Th17 to regulatory T cell ratio. These data suggest that inhibition of pathogenic IL-17 via tumor necrosis factor blockade is associated with improvement in immune dysregulation in HS and may provide a rationale for targeting IL-17 in the disease.

[Systemic lupus erythematosus : Unusual cutaneous manifestations]

BACKGROUND

Various different mucocutaneous symptoms may affect up to 80 % of systemic lupus erythematosus (SLE) patients.

OBJECTIVES

To investigate, various unspecific, but otherwise typical clinical symptoms of skin and mucous membranes that arise in SLE patients other than those defined as SLE criteria such as butterfly rash, chronic cutaneous lupus erythematosus, oral ulcers, and increased photosensitivity.

MATERIALS AND METHODS

Extensive search of peer-reviewed scientific articles was performed, medical histories of several SLE patients seen in our department were analyzed, and the rare disease courses in three SLE patients are presented.

RESULTS

Here we present a variety of unspecific but typical mucocutaneous manifestations in SLE patients: periungual erythema, periungual telangiectasia and periungual splinter hemorrhage, papules on the dorsum of the hands, scaling erythema, sometimes associated with necrosis, especially of the ears, along with complement deficiency, and the bizarre necroses of antiphospholipid syndrome. Furthermore, we show the typical clinico-histological features of neutrophilic urticarial dermatosis, as well as those of bullous SLE and finally a severe course of bacterial sepsis with Neisseria flavescens/macacae.

CONCLUSIONS

Here we show several unspecific but rather typical mucocutaneous symptoms in lupus patients that are indicative of SLE and thus may lead to an early diagnosis. Also, life-threatening bacterial sepsis may occur with microorganisms that are commonly considered "apathogenic", such as Neisseria flavescens/macacae, which exclusively affect immunosuppressed patients.

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.