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Background: Acute febrile neutrophilic dermatosis, also commonly referred to as Sweet syndrome, is often associated with tumors, infections, immune disorders and medications. FLT3 inhibitor-induced Sweet syndrome is a rare complication., Methods and Results: We report a patient with relapsed and refractory acute monocytic leukemia harboring high-frequency FLT3-ITD and DNMT3a mutations. The FLT3 inhibitor gilteritinib was administered for reinduction therapy after failure of chemotherapy with a combination of venetoclax, decitabine, aclarubicin, cytarabine and granulocyte colony-stimulating factor. The leukemia patient achieved remission after 1 month of treatment. However, Sweet syndrome induced by gilteritinib, which was confirmed by skin biopsy, developed during induction therapy. Similar cases of Sweet syndrome following FLT3 inhibitor therapy for acute myeloid leukemia were reviewed., Conclusion: Attention should be given to this rare complication when FLT3 inhibitors are used for acute myeloid leukemia therapy, and appropriate treatments need to be administered in a timely manner.

Histiocytoid Sweet syndrome (H-SS) is a histopathological variant of Sweet syndrome (SS) defined by cutaneous infiltration of immature myeloid cells morphologically resembling histiocytes. The association of H-SS with underlying malignancy, particularly myelodysplastic syndromes, is well-established. Myelodysplasia cutis (MDS-cutis) has been proposed to describe cases historically diagnosed as H-SS but characterized by shared clonality of the myeloid infiltrate in skin and bone marrow. Therefore, identifying patients who might have MDS-cutis is critical for the management of the associated hematologic malignancy. VEXAS syndrome, an adult-onset autoinflammatory disease, should also be included in the histopathologic differential diagnosis of H-SS, as it shares clinical and pathologic features with MDS-cutis. Through the presentation of two cases, we aim to highlight the defining features and key clinical implications of MDS-cutis and VEXAS syndrome., (© 2024 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

An otherwise healthy 4-week-old term female of Japanese heritage presented with a 1-week history of asymptomatic progressive, generalized skin lesions. The lesion morphology, distribution, and dermatopathology result was consistent with Sweet syndrome. The patient was found to have a congenital type H rectovestibular fistula. This case highlights the rare association of rectovestibular fistula in neonatal Sweet syndrome which has only been described in neonates of Japanese heritage., (© 2024 Wiley Periodicals LLC.)

Background: Sweet syndrome (SS) is a rare dermatological adverse reaction caused by granulocyte colony-stimulating factor (G-CSF), but the characteristics of G-CSF-induced SS are unclear. This study aims to elucidate the characteristics of G-CSF-induced SS and offer guidance for its prevention and management., Methods: We collected relevant case reports of G-CSF-induced SS by searching pertinent databases until June 30, 2024, and synthesized the data for retrospective analysis., Results: A total of fifty patients were analyzed, with a median age of 44 years (1.7-77). The onset of SS occurred between 2 and 90 days post-administration, with a median onset time of 7 days. The predominant cutaneous manifestations included papules/plaques (74.0%), nodules (32.0%), and vesicles/bullae (24.0%). Fever presented in 74.0% of cases, while extra-cutaneous symptoms appeared in 32% of patients. Skin biopsy revealed key findings such as dermal diffuse neutrophil infiltration (97.8%), leukocytoclasis (19.1%), and dermal papillary edema (27.7%). Following both the cessation of G-CSF and systemic corticosteroids treatment, patients showed symptomatic improvement at a median interval of 7 days (2-70)., Conclusion: Clinicians should remain vigilant for the risk of SS during G-CSF administration. Skin biopsy plays a crucial role in confirming SS diagnosis. G-CSF-induced SS exhibits a favorable response to corticosteroids, and re-administration of G-CSF should be avoided due to the risk of symptom recurrence., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: Sweet syndrome (acute febrile neutrophilic dermatosis) is an uncommon inflammatory disorder characterized by the abrupt appearance of painful, edematous, and erythematous papules, plaques, or nodules on the skin. There are various subtypes, such as classical, drug-induced, malignancy-associated, and the less common variant giant cellulitis-like Sweet syndrome. This case is unique due to its presentation of the giant cellulitis-like variant of Sweet syndrome in a patient from Ethiopia. The unusual distribution of the skin lesions and the initial lack of response to antibiotics make this case particularly noteworthy. It underscores the importance of considering Sweet syndrome in differential diagnoses when faced with atypical skin manifestations and ineffective antibiotic treatment. This contribution adds valuable insights to the scientific literature by highlighting the need for heightened awareness of this rare variant and improving diagnostic accuracy in similar clinical scenarios., Case Presentation: A 60-year-old Ethiopian male patient who presented to the accident and emergency department with a 5-day history of fever, chills, sweating, and rigor accompanied by a reddish skin color change around the anterolateral region of the right chest wall. On physical examination, there were erythematous, indurated tender plaques with ill-defined borders over the right antero- and posterolateral chest wall with extension to the lateral part of the right neck and medial aspect of the right arm. Subsequently, the patient was started on antibiotics, but there was a suboptimal response. Skin biopsy revealed features suggestive of giant cellulitis-like Sweet syndrome. He was then started on steroids, which significantly improved his symptoms., Conclusion: A cautious stance is essential when identifying Sweet syndrome in individuals displaying erythematous plaque-like skin lesions in atypical areas of the body with uneven distribution. Such presentation may signal Sweet syndrome rather than a common infection. If conventional treatments, such as antibiotics, fail to resolve symptoms, consider Sweet syndrome as a potential diagnosis. This approach ensures timely and appropriate treatment, preventing treatment delay and misdiagnosis., (© 2024. The Author(s).)

Cryptococcoid Sweet syndrome (cSS) is a recently described clinical and histological variant of Sweet syndrome (SS). Its cutaneous presentation is similar to the classical form of SS but it includes atypical findings, such as capsular and yeast-like structures on microscopy that are reminiscent of Cryptococcus species. However, in cSS, fungal staining and cultural examination are negative, whereas myeloperoxidase (MPO) staining on biopsy specimens is typically positive. Due to the rarity and the diagnostic challenge represented by this disease, its extracutaneous involvement, and the latency in its diagnosis, this condition is frequently associated with poor prognosis. In this study, we report the case of a cSS patient with a positive outcome., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Volonté, Fiandrino, Vassallo, Barruscotti, Giorgini, Tomasini and Brazzelli.)

Neutrophilic dermatosis, or Sweet syndrome, is a cutaneous disorder caused by neutrophilic infiltration in the upper dermis. It has been associated with medications, infections and malignancies but to date it has not been associated with femoral arterial angioplasty or stenting. We present the case of a 75-year-old female who, after angioplasty and stent placement of the right superficial femoral artery, developed right heel pain with ulceration that did not respond to broad antibiotics. She underwent incision and drainage twice without improvement; both times produced negative cultures. She then underwent a punch biopsy by dermatology, which was consistent with acute spongiotic and other neutrophilic dermatoses. She was started on prednisone with immediate improvement of her symptoms. She was discharged to a rehabilitation centre with a prednisone taper and antibiotics. This report highlights the importance of maintaining Sweet syndrome on the differential for cellulitis as it is a rare mimicry of other infectious and non-infectious aetiologies, which are common in the perioperative space. Early treatment is crucial to improve symptoms, outcomes, healthcare cost and potentially the length of stay., Learning Points: Sweet syndrome, a rare skin condition related to neutrophil infiltration, may be triggered by angioplasty.Sweet syndrome is easily misdiagnosed as infectious conditions such as cellulitis., Competing Interests: Conflicts of Interests: The Authors declare that there are no competing interests., (© EFIM 2024.)

Neutrophilic dermatosis of the dorsal hands (NDDH) is a rare, challenging condition characterized by its acute febrile onset, neutrophilic dermal infiltrate seen on histology, and frequent association with hematologic disorders. This case report presents a longitudinal follow-up of NDDH in an 80-year-old male with significant comorbid conditions, including atrial fibrillation, chronic systolic heart failure, venous insufficiency, and gastroesophageal reflux disease. Over six clinic visits, we document the patient's clinical progression, highlighting key changes in presentation, diagnostic findings, and the multifaceted approach to management, including the use of systemic and topical therapies. Notably, the treatment strategy was adapted in response to diagnostic tests revealing methicillin-resistant Staphylococcus aureus (MRSA) and Group B Streptococcus (GBS), complicating the patient's condition. Despite the challenges posed by the patient's comorbidities, which limited the use of certain medications, the patient showed significant improvement with a treatment approach primarily involving topical and systemic steroids. The observed improvement emphasizes the effectiveness of modifying therapy based on lesion regression and the patient's overall condition. This case underscores the critical need for accurate diagnosis, the complexities of managing NDDH in patients with multiple health conditions, and the value of adaptability in treatment plans. Through this detailed longitudinal case study, we contribute insights into the progression and management of NDDH, emphasizing the need for ongoing research and a flexible approach to treatment., Competing Interests: Human subjects: Consent was obtained or waived by all participants in this study. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2024, Bohman et al.)

Splenic abscesses are typically infectious in nature but have rarely been reported as an extraintestinal manifestation of inflammatory bowel disease, particularly of Crohn's disease. In the United States, reported cases are even more scarce. We present a case of aseptic splenic abscess with concomitant Sweet syndrome in a middle-aged woman with newly diagnosed Crohn's disease. Extensive workup was required to reach final diagnosis, and she rapidly improved with corticosteroid therapy and has been maintained on risankizumab. We aim to contribute to limited data and heighten clinician awareness of these atypical extraintestinal manifestations., (© 2024 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of The American College of Gastroenterology.)

Competing Interests: None disclosed.

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., (© 2024 International Federation of Gynecology and Obstetrics.)

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., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Saito, Kewalramani, Peng, Magnarelli and Lederman.)

VEXAS syndrome is a rare entity secondary to UBA1 gene mutations, located on the X chromosome. This mutation generates, as a consequence, a characteristic vacuolation on haematopoietic stem-cells. It is characterized by multiple autoinflammatory and haematologic manifestations, which respond and end up being dependent on corticosteroid treatment. In this publication we present a 2-case series diagnosed at our hospital and make a brief literature review of the published evidence so far., (Copyright © 2024 Elsevier España, S.L.U. and Sociedad Española de Reumatología y Colegio Mexicano de Reumatología. All rights reserved.)

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., Competing Interests: Conflict of interest None declared., (Copyright © 2023 Elsevier Inc. All rights reserved.)

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., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Sweet syndrome is a rare cutaneous condition with a broad clinical differential diagnosis. It can be classified into 3 subtypes: classic, malignancy-associated, and drug-induced. There are numerous associated disorders and provoking medications. Uncommonly, it can present as a multiorgan disease and cause significant morbidity. Systemic corticosteroids are the gold standard of treatment and yield rapid improvements in both lesions and symptoms. Nonsteroidal therapies may be effective alternatives, although high-quality comparative data are lacking. Some treatments for Sweet syndrome have paradoxically been implicated in the induction of disease., Competing Interests: Disclosures The authors have no relevant conflicts to disclose., (Copyright © 2023 Elsevier Inc. All rights reserved.)

The term neutrophilic dermatosis encompasses a heterogeneous group of diseases, often associated with an underlying internal noninfectious disease, with an overlapping histopathologic background characterized by perivascular and diffuse neutrophilic infiltrates in one or more layers of the skin; extracutaneous neutrophilic infiltrates may be associated. Neutrophilic dermatoses are not frequent in children and, when they appear in this age group, represent a diagnostic and therapeutic challenge. Apart from the classic neutrophilic dermatoses such as pyoderma gangrenosum, Sweet syndrome, and Behçet disease, a neutrophilic dermatosis can be the presentation of rare genetic diseases of the innate immune system, such as autoinflammatory diseases., Competing Interests: Disclosure The authors declare that they have no conflicts of interest., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Neutrophilic panniculitides are a heterogeneous group of inflammatory disorders encompassing many different entities. This review article focuses on the epidemiology, pathogenesis, clinicopathological features, diagnosis, and treatment of selected diseases. Patients often seek care due to systemic involvement, but the variable presentation of panniculitides can present a diagnostic challenge. Most therapeutic modalities for neutrophilic disorders are anecdotal at best with a notable lack of standardization of the responses to medications. There is an urgent need for a larger multi-institutional collaboration to address the unmet needs of these challenging, yet rare conditions., (Copyright © 2023 Elsevier Inc. All rights reserved.)

In 2005, a new histologic variant of Sweet syndrome (SS) has been described and termed histiocytoid SS (HSS). Clinically, patients had a typical SS, but on skin biopsy, the infiltrates were composed of immature nonblast myeloid cells. Nearly 50% of patients with HSS have myelodysplastic syndrome (MDS). HSS may be the first manifestation leading to the diagnosis of MDS. In 2015, a new category of myeloid dermatosis has been proposed, called myelodysplasia cutis, describing the specific skin infiltration by myelodysplastic cells in patients with MDS., (Copyright © 2023 Elsevier Inc. All rights reserved.)

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., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Background: A dysregulated immune response has been implicated in Sweet syndrome (SS) pathogenesis; however, cytokine profiles across different conditions associated with SS - including adult-onset immunodeficiency (AOID) due to anti-interferon (IFN)-γ autoantibodies - remain unknown., Objective: To investigate alterations in inflammatory cytokines in skin lesions of distinct subtypes of SS., Methods: Skin biopsies were collected from 42 AOID- and 52 non-AOID-associated SS patients and 18 healthy controls. The comparative immunohistochemical study was conducted using monoclonal antibodies against interleukin (IL)-1β, IL-6, IL-17, IFN-γ, and tumor necrosis factor-α on paraffin-embedded sections. The quantitative percentage positivity and intensity were calculated using computer-based image analysis., Results: The results showed stronger and more diffuse dermal immunoreactivity for IFN-γ and IL-17 in the AOID-associated ( p < 0.001 and p < 0.001, respectively) and non-AOID-associated SS ( p < 0.001 and p < 0.001, respectively) groups. However, no significant differences in the levels of these two cytokines were observed between the AOID- and non-AOID-associated SS groups. Increased expression of IFN-γ together with IL-17 was also noted in almost all subtypes among non-AOID-associated SS., Conclusions: These results demonstrate that IFN-γ and IL-17 are implicated in immunopathology of all SS subtypes, including AOID-associated SS, despite the presence of anti-IFN-γ autoantibodies., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Chieosilapatham, Daroontum, Suwansirikul, Chaiwarith, Phinyo, Chaowattanapanit, Choonhakarn, Kiratikanon, Rujiwetpongstorn, Tovanabutra, Chiewchanvit and Chuamanochan.)

VEXAS (Vacuoles, E1 enzyme, X-linked, Autoinflammatory, Somatic) syndrome is an adult-onset autoinflammatory syndrome characterized by somatic mutations in the UBA1 gene and is considered the prototype of hematoinflammatory diseases. Patients with VEXAS syndrome exhibit inflammatory and hematological manifestations that can lead to clinical diagnoses such as relapsing polychondritis, polyarteritis nodosa, Sweet syndrome, and myelodysplastic syndrome. Diagnosis requires bone marrow evaluation to identify cytoplasmic vacuoles in myeloid and erythroid precursors. However, genetic confirmation of mutations in UBA1 is necessary. Treatment is challenging and often involves glucocorticoids and immunosuppressants with variable responses. Hypomethylating agents and allogenic haemopoietic stem cell transplant are considered promising therapies. Prognosis is influenced by genetic and clinical factors. The aim of this review is to provide an overview of the pathogenesis, clinical presentation, treatment, and prognosis of VEXAS syndrome for the Latin American medical community., (Copyright © 2023. Published by Elsevier España, S.L.U.)

In 2020, Beck et al 1 described a novel adult autoinflammatory syndrome entitled VEXAS (Vacuoles, E1 enzyme, X-linked, Autoinflammatory, Somatic), a newly-discovered disorder that connected previously unrelated inflammatory syndromes and a prototype for a new class of hematoinflammatory diseases. 2 Eighty-nine percent of published cases have documented skin involvement, but despite the high incidence and diagnostic accessibility of skin manifestations, there has been little focus on the dermatological features of VEXAS syndrome thus far. A PubMed search of all published case reports of VEXAS syndrome to date was performed, with inclusion of all cases confirmed by genetic sequencing, and this review summarizes the reported dermatological signs. There have already been 141 confirmed published cases since original publication, 126 of which had documented cutaneous signs. 1-34 A wide range of skin presentations are reported, including Sweet-like urticated and tender erythematous nodules, cartilaginous involvement with chondritis, cutaneous vasculitis, and periorbital angiodema. 1-34 Many patients had been diagnosed with Sweet syndrome, relapsing polychondritis, polyarteritis nodosa, or erythema nodosum. 1-34 Hallmarks of skin histopathology are a neutrophilic dermatosis with coexisting or exclusive leukocytoclastic vasculitis. 1 The new classification therefore helps link previously disparate inflammatory skin conditions into a unifying pathophysiological pathway., Competing Interests: Conflicts of interest None disclosed., (Copyright © 2022 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.)

Sweet syndrome is a rare complication of azathioprine treatment with unelucidated clinical features. The purpose of this study was to investigate the clinical characteristics of azathioprine-induced Sweet syndrome (AISS) and provide a reference for diagnosis, treatment and prognosis. We collected relevant case reports of AISS by searching Chinese and English databases from 1960 to December 31, 2022, extracted the data and carried out a retrospective analysis. The median age of the 44 patients was 50 (range 9-89) years, and they included 32 males (72.7%). Fever (86.4%) and arthralgia (31.8%) were the most common clinical symptoms. The skin lesions were mainly pustules (54.5%), papules (40.9%), plaques (40.9%) and nodules (31.8%), which were mainly distributed on the extremities (54.5%), face (38.6%) and hands (36.4%). Laboratory examination revealed neutropenia (65.9%) as well as elevated C-reactive protein (63.6%) and erythrocyte sedimentation (40.9%) rates. Histopathology of the lesioned skin showed neutrophil infiltration (93.2%) and dermal edema (38.6%). Symptom relief was achieved at a median time of 7 days (range 2-28 days) after azathioprine discontinuation in all patients. Nine patients (20.5%) had skin lesions that recurred within 24 h after taking azathioprine again. Clinicians and pharmacists should grasp the regularity and characteristics of AISS and should not recommend the readministration of azathioprine, to avoid the recurrence of Sweet syndrome., (© 2023. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Competing Interests: Conflicts of interest the authors declare no conflicts of interest. H.Z. and P.X. share first authorship.

Competing Interests: None disclosed.