Neutrophilic Dermatoses: a Clinical Update

Molecular Characteristics of Sweet Syndrome: A Systematic Review

Sweet syndrome (SS), originally described as acute febrile neutrophilic dermatosis, is a rare inflammatory skin condition, considered the prototype of neutrophilic dermatoses. It is characterised by the sudden onset of well-defined tender papules, plaques and nodules often accompanied by fever, neutrophilia and elevated markers of inflammation. Several variants have been described both clinically and histopathologically. Classifications include idiopathic, malignancy-associated, and drug-induced SS. The exact pathogenesis of SS is still unclear; however, recent findings have shed light on the role of dermal infiltrating neutrophils-in the context of innate immunity, and signalling pathways related to adaptive immunity. To critically analyse the current molecular landscape of SS and discuss the recent evidence supporting novel potential immune mediators and biological signalling pathways involved in SS pathogenesis. The methodology followed PRISMA guidelines and included two bibliographical databases, searching articles published until 17 December 2023. Titles, abstracts and full text were reviewed independently by two assessors, while other two investigators resolved any opinion differences. Of 3303 records identified through database search, 22 articles met the eligibility criteria for inclusion. We considered experimental studies that performed molecular analysis, in terms of cytokines quantification, gene expression and/or immunofluorescence/immunohistochemistry. As for the latter, only studies aimed at characterising the nature of the inflammatory infiltrate and potential mechanisms leading to distinct forms of cutaneous inflammatory cell influx were included. Overall, we described research on 202 SS patients (177 skin biopsies and 25 blood specimens) revealing the predominant role of neutrophil activation and abnormal proliferation as unifying mechanisms in different SS subtypes. Interestingly, we found that hyperactivation of the IL-1 pathway might occur only in a subset of SS patients and adaptive immunity could also play a role in the pathogenic scenario of SS, with a potential significant role of IL-17 axis. This systematic review provides a wealth of evidence on the molecular landscape of SS, although further research is needed to a deeper understanding of the patho-mechanisms of this rare disease and hopefully lead to targeted therapeutic approaches.

Sweet syndrome in pregnancy: A narrative review

The aim of this review is to increase obstetrician awareness of pregnancy-associated Sweet syndrome. Patients present with fever, leukocytosis, and skin eruption, which can mimic other infectious or inflammatory conditions, but do not respond to antibiotics. A search using PubMed, EMBASE, and Web of Science Core Collection was conducted to review all reported cases of pregnancy-associated Sweet syndrome, an acute febrile neutrophilic dermatosis occurring during pregnancy or postpartum. A total of 33 episodes among 30 patients were identified, with the majority (54.5% [18]) of cases occurring within the second trimester. Among the 30 patients, skin lesions most commonly affected the head and neck (73.3% [22]), with rare oral or ocular involvement. Leukocytosis was the most common laboratory finding, reported in 96.7% [29] of patients, with neutrophil predominance noted in 70.0% [21]. The diagnosis was confirmed for all patients with pathognomonic results of skin biopsies. Of the 27 cases detailing treatment, systemic corticosteroids were most frequently used (19 cases), followed by conservative management (seven cases), and dapsone (one case). The dapsone-treated patient and 15 of the 19 steroid-treated patients experienced resolution, but additional management strategies were required in the remaining four individuals. Spontaneous resolution occurred during pregnancy in six of the seven conservatively managed individuals, with one patient experiencing spontaneous abortion shortly after skin eruption at 10 weeks of gestation. No associated maternal deaths were reported. Obstetric complications of pregnancy-associated Sweet syndrome included endomyometritis, sterile placental abscesses, and abdominal wall necrosis. Delivery of healthy infants occurred in 24 of the 25 cases that presented fetal outcome, which included two infants who underwent medically indicated preterm deliveries.

Sweet syndrome associated with moderate leukocyte adhesion deficiency type I: a case report and review of the literature

Sweet syndrome is an acute febrile neutrophilic dermatosis characterized by the infiltration of neutrophils into the skin. It may occur idiopathically or be linked to malignancies, inflammatory or autoimmune diseases. Leukocyte adhesion deficiency type I (LAD-I) is an inborn error immunity wherein leukocytes lack adhesion molecules necessary for migration to infection sites due to mutations in the CD18 gene encoding β2 integrins. We present a case of a 16-month-old female initially diagnosed and treated for Sweet syndrome based on histopathological findings with recurrent flare episodes. Subsequent workup revealed LAD-I, making this case the first documented association between Sweet syndrome and LAD-I. Moreover, we reviewed the pertinent literatures detailing the concurrence of neutrophilic dermatosis and immunodeficiency disorders. This case underscores the significance of comprehensive evaluation for Sweet syndrome patients who are refractory to conventional treatments.

Neutrophilic dermatosis in a patient with an IKZF1 variant and a review of monogenic autoinflammatory disorders presenting with neutrophilic dermatoses

Monogenic diseases of immune dysregulation should be considered in the evaluation of children presenting with recurrent neutrophilic dermatoses in association with systemic signs of inflammation, autoimmune disease, hematologic abnormalities, and opportunistic or recurrent infections. We report the case of a 2-year-old boy presenting with a neutrophilic dermatosis, found to have a novel likely pathogenic germline variant of the IKAROS Family Zinc Finger 1 (IKZF1) gene; the mutation likely results in a loss of function dimerization defective protein based on reports and studies of similar variants. IKZF1 variants could potentially lead to aberrant neutrophil chemotaxis and development of neutrophilic dermatoses. Long-term surveillance is required to monitor the development of hematologic malignancy, autoimmunity, immunodeficiency, and infection in patients with pathogenic IKZF1 germline variants.

Retiform Ulceration and Bullae on the Bilateral Thighs

A man with a history of polysubstance use presents with new bullae on his bilateral lower extremities. What is your diagnosis?

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.

Neutrophilic dermatoses as a manifestation of a systemic lupus erythematosus flare

Neutrophilic dermatoses (NDs) refer to a group of cutaneous conditions histologically characterized by the dense accumulation of neutrophils in the skin in the absence of infection. NDs have been associated with underlying autoimmune connective tissue disorders (CTDs) such as systemic lupus erythematosus (SLE), Sjogren's syndrome, and dermatomyositis. We describe a case of neutrophilic dermatoses as a manifestation of a SLE flare.

Sweet Syndrome: Clinical Presentation, Malignancy Association, Autoinflammatory Disorders and Treatment Response in a Cohort of 93 Patients with Long-term Follow-up

Sweet syndrome is a neutrophilic dermatosis associated with multiple disorders. This retrospective case-series study of patients with Sweet syndrome in a tertiary hospital in Spain from 2001 to 2021, explores clinicopathological characteristics of Sweet syndrome and variables associated with malignancy, presence of autoinflammatory disorders and differences between histological subtypes. A total of 93 patients were identified: 30% idiopathic, 34% malignancy-associated, 29% reactive to infections or drug-associated, and 6% with an autoimmune/inflammatory condition. Acute myeloid leukaemia was the most common malignancy (16/93) followed by myelodysplastic syndrome (7/93). Patients with acute myeloid leukaemia presented isolated flares, marked cytopaenia and rapid response to treatment, whereas myelodysplastic syndrome followed a chronic-recurrent course. The most frequent associated medications and inflammatory  disorders were filgrastim and hydroxyurea (n = 2);  and inflammatory bowel disease (n = 4). In addition, 3 patients were diagnosed with VEXAS syndrome. Male sex (p = 0.006), fever (p = 0.034), increased erythrocyte sedimentation rate (p < 0.001), anaemia (p < 0.001), and thrombocytopaenia (p < 0.001) were associated with malignancy. Histologically, patients were classified as classic (60%), histiocytoid (22.5%) or subcutaneous (15%), with pain (p = 0.011) and nodules (p < 0.001) being associated with subcutaneous-Sweet syndrome. Sweet syndrome in the context of cytopaenia should alert the presence of malignancy. An  acquired autoinflammatory condition should be explored  in relapsing Sweet syndrome with myelodysplastic syndrome. A minimum follow-up of 6 months is recommended.

Clinical, Histopathological and Molecular Spectrum of Cutaneous Lesions in Myelodysplastic Syndrome and Myeloproliferative Neoplasms (MDS/MPN): An Integrative Review

Myeloid neoplasms and acute leukemias include different entities that have been recently re-classified taking into account molecular and clinicopathological features. The myelodysplastic syndrome/myeloproliferative neoplasm (MDS/MPN) category comprises a heterogeneous group of hybrid neoplastic myeloid diseases characterized by the co-occurrence of clinical and pathological features of both myelodysplastic and myeloproliferative neoplasms. The most frequent entity in this category is chronic myelomonocytic leukemia (CMML) which is, after acute myeloid leukemia (AML), the main myeloid disorder prone to develop cutaneous manifestations. Skin lesions associated with myelodysplastic and myeloproliferative neoplasms include a broad clinical, histopathological and molecular spectrum of lesions, poorly understood and without a clear-cut classification in the current medical literature. The aim of this review is to describe and classify the main clinical, histopathological and molecular patterns of cutaneous lesions in the setting of MDS/MPN in order to improve the diagnostic skills of the dermatologists, hematologists and pathologists who deal with these patients.

Treatment Strategies in Neutrophilic Dermatoses: A Comprehensive Review

Neutrophilic dermatoses (NDs) are a group of noninfectious disorders characterized by the presence of a sterile neutrophilic infiltrate without vasculitis histopathology. Their physiopathology is not fully understood. The association between neutrophilic dermatoses and autoinflammatory diseases has led some authors to propose that both are part of the same spectrum of diseases. The classification of NDs depends on clinical and histopathological features. This review focuses on the recent developments of treatments in these pathologies.

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.

Neutrophil, NETs and Behçet's disease: A review

Behçet's disease (BD) is a chronic systemic vasculitis characterized by recurrent oral and genital ulcers, skin lesions, articular, neurological, vascular and sight-threatening ocular inflammation. BD is thought to share both autoimmune and autoinflammatory disease features. BD is triggered by environmental factors such as infectious agents in genetically predisposed subjects. Neutrophils seem to play an instrumental role in BD and recent works regarding the role of neutrophils extracellular traps (NETs) provides new insight in the pathophysiology of BD and the mechanisms involved in immune thrombosis. This review provides a recent overview on the role of neutrophils and NETs in the pathogenesis of BD.

An Overview of Clinical Manifestations of Dermatological Disorders in Intensive Care Units: What Should Intensivists Be Aware of?

Acute skin failure is rarely the primary diagnosis that necessitates admission to an intensive care unit. Dermatological manifestations in critically ill patients, on the other hand, are relatively common and can be used to make a key diagnosis of an adverse drug reaction or an underlying systemic illness, or they may be caused by factors related to a prolonged stay or invasive procedures. In intensive care units, their classification is based on the aetiopathogenesis of the cutaneous lesion and, in the meantime, distinguishes critical patients. When evaluating dermatological manifestations, several factors must be considered: onset, morphology, distribution, and associated symptoms and signs. This review depicts dermatological signs in critical patients in order to lay out better recognition.

Pyoderma gangrenosum after deep inferior epigastric perforator flap: how prompt diagnosis and treatment can avoid surgical debridement and further morbidity

Pyoderma gangrenosum (PG) is a skin disorder characterized by painful, enlarging necrotic ulcers with bluish borders surrounded by advancing zones of erythema. The key histologic feature is neutrophilic infiltration of the superficial and deep layers of the dermis and the absence of microorganisms. Although rare and associated with autoimmune diseases such as rheumatoid arthritis, ulcerative colitis and Crohn's disease, the diagnosis is commonly missed at presentation and patients are often treated for infection with antibiotics and surgical debridement. We present a case of PG in a 51 year-old woman after a deep inferior epigastric perforator (DIEP) flap for breast reconstruction who was promptly diagnosed and treated with steroids with appropriate response. Our case highlights the importance of rapid diagnosis and treatment of this disease to avoid incorrect management including surgical debridement, which can exacerbate the disease and increase its morbidity.