Histiocytoid Sweet Syndrome Is More Frequently Associated With Myelodysplastic Syndromes Than the Classical Neutrophilic Variant: A Comparative Series of 62 Patients

Skin Manifestations of VEXAS Syndrome and Associated Genotypes

Importance

VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) syndrome is a newly defined genetic disease with an estimated prevalence of 1 in 4269 men older than 50 years and is marked by systemic inflammation, progressive bone marrow failure, and inflammatory cutaneous manifestations.

Objective

To define the spectrum of cutaneous manifestations in VEXAS syndrome and the association of these findings with clinical, genetic, and histological features.

Design, Setting, and Participants

This observational cohort study included data from 112 patients who were diagnosed with VEXAS-defining genetic variants in UBA1 between 2019 and 2023. Data were collected from medical record review or from patients with VEXAS directly evaluated at the National Institutes of Health in Bethesda, Maryland.

Main Outcomes and Measures

To define the spectrum of cutaneous manifestations in VEXAS in association with genetic, histological, and other clinical findings. A secondary outcome was cutaneous response to treatment in VEXAS.

Results

Among the 112 patients (median [range] age, 69 [39-79] years; 111 [99%] male), skin involvement was common (93 [83%]), and the most frequent presenting feature of disease (68 [61%]). Of 64 histopathologic reports available from 60 patients, predominant skin histopathologic findings were leukocytoclastic vasculitis (23 [36%]), neutrophilic dermatosis (22 [34%]), and perivascular dermatitis (19 [30%]). Distinct pathogenic genetic variants were associated with specific cutaneous manifestations. The p.Met41Leu variant was most frequently associated with neutrophilic dermal infiltrates (14 of 17 patients [82%]), often resembling histiocytoid Sweet syndrome. In contrast, the p.Met41Val variant was associated with vasculitic lesions (11 of 20 patients [55%]) with a mixed leukocytic infiltrate (17 of 20 patients [85%]). Oral prednisone improved skin manifestations in 67 of 73 patients (92%). Patients with VEXAS treated with anakinra frequently developed severe injection-site reactions (12 of 16 [75%]), including ulceration (2 of 12 [17%]) and abscess formation (1 of 12 [8%]).

Conclusions and Relevance

Results of this cohort study show that skin manifestations are a common and early manifestation of VEXAS syndrome. Genetic evaluation for VEXAS should be considered in older male patients with cutaneous vasculitis, neutrophilic dermatoses, or chondritis. Awareness of VEXAS among dermatologists is critical to facilitate early diagnosis.

Clinical and histological features of histiocytoid Sweet syndrome associated with VEXAS syndrome

BACKGROUND

VEXAS (Vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) syndrome is caused by acquired somatic mutations in UBA1. Sweet-syndrome-like skin disorders [and especially histiocytoid Sweet syndrome (HSS)] may be associated with VEXAS syndrome.

OBJECTIVES

To characterize the clinical and histopathological features of HSS in patients with VEXAS syndrome.

METHODS

Skin biopsies with a histological diagnosis of HSS at Rennes University Medical Center (Rennes, France) between October 2011 and January 2022 were reviewed in this study. Sanger sequencing and digital polymerase chain reaction were used to screen skin, blood and bone marrow samples for UBA1 variants, and thus classify patients as having VEXAS syndrome or not. We evaluated the clinical, histological and molecular (UBA1) characteristics of patients with or without VEXAS syndrome.

RESULTS

We compared 15 skin biopsies from 7 patients found to have VEXAS syndrome and 19 skin biopsies from 15 patients without VEXAS syndrome. Persistent C-reactive protein elevation, macrocytosis, anaemia and haematological malignancies were more prevalent in patients with VEXAS syndrome [6/7 (86%), 6/7 (86%), 7/7 (100%) and 6/7 (86%), respectively] than in patients without [5/14 (36%), 6/15 (40%), 8/15 (53%) and 8/15 (53%), respectively]. These features sometimes appeared after the first skin manifestations, and a UBA1 mutation was found in the skin of five patients with VEXAS syndrome. Dermal infiltration by reniform histiocytoid cells (myeloperoxidase-positive and/or CD163-positive) and a periadnexal distribution were more frequently observed in VEXAS syndrome biopsies [15/15 (100%) and 3/15 (20%), respectively, vs. 11/19 (58%) and 0/19 (0%) in non-VEXAS syndrome biopsies, respectively].

CONCLUSIONS

Our findings might help pathologists to consider a diagnosis of VEXAS syndrome and to initiate early genetic testing.

Cutaneous manifestations of myelodysplastic syndrome: A systematic review

Myelodysplastic syndrome (MDS) may present with specific skin lesions, such as leukaemia cutis, which is a well known poor prognostic marker of leukaemia with a high risk of acute leukaemic transformation. However, less is known regarding non-specific cutaneous manifestations of MDS including the prevalence, types and their prognostic and therapeutic significance, which we aimed to determine through this systematic review. We searched electronic databases (PubMed, Medline and EMBASE) from inception up to 26 January 2023 for studies reporting cutaneous manifestations of MDS. Eighty eight articles (case reports n = 67, case series n = 21), consisting of 134 patients were identified. We identified 6 common cutaneous manifestations: neutrophilic dermatoses (n = 64), vasculitis (n = 21), granulomatous (n = 8), connective tissue disease (CTD) (n = 7; composed of dermatomyositis (n = 5), cutaneous lupus erythematosus (n = 1), and systemic sclerosis (n = 1)), panniculitis (n = 4), immunobullous (n = 1), and other (n = 29). Cutaneous features either occurred at time of MDS diagnosis in 25.3%, preceding the diagnosis in 34.7% (range 0.5-216 months), or after diagnosis in 40.0% (range 1-132 months). Prognosis was poor (40.2% death) with 34.1% progressing to acute myeloid leukaemia (AML). 50% of those with MDS who progressed to AML had neutrophilic dermatoses (p = 0.21). Myelodysplastic syndrome was fatal in 39.2% of neutrophilic dermatoses (median time from onset of cutaneous manifestation: 12 months), 50% of vasculitis (7.5 months), 62.5% of granulomatous (15.5 months) and 14.3% of CTD (7 months). Recognition of patterns of cutaneous features in MDS will improve early diagnosis and risk stratification according to subtype and associated prognosis.

Histiocytoid Sweet's Syndrome in the Setting of Myelodysplastic Syndrome

Acute febrile neutrophilic dermatosis, or Sweet's syndrome, is characterized by tender, edematous papules and plaques, favoring the upper extremities and the head and neck regions. The classic variant of Sweet's syndrome involves a predominantly neutrophilic dermal infiltrate on histopathology. However, histiocytoid Sweet's syndrome has been noted to have a primary histiocytoid mononuclear infiltrate and is typically found in patients with malignancies such as myelodysplasia. This case report discusses the treatment of histiocytoid Sweet's syndrome in an immunocompromised patient with a recent history of Mycobacterium avium complex infection and latent tuberculosis in the setting of myelodysplastic syndrome.

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.

Sweet Syndrome and Neutrophilic Dermatosis of the Dorsal Hands

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.

Myelodysplasia Cutis

CONTEXT.—

Myelodysplasia cutis is an emerging concept in cutaneous neoplasia. Many of these cases were previously included under the umbrella of histiocytoid Sweet syndrome. However, with the advent of next-generation sequencing, cutaneous involvement by myelodysplastic syndrome is being increasingly recognized.

OBJECTIVE.—

To review histiocytoid Sweet syndrome and myelodysplasia cutis and discuss our current understanding of these entities. Additionally, to discuss how next-generation sequencing can be applied in the evaluation of cutaneous infiltrates of immature histiocytoid cells.

DATA SOURCES.—

The English-language literature from 2005 to 2023 on the topic of histiocytoid Sweet syndrome and myelodysplasia cutis was reviewed.

CONCLUSIONS.—

Biopsy specimens showing infiltrates of histiocytoid, immature myeloid cells may represent cutaneous involvement by myelodysplastic syndrome. Close clinical correlation is recommended in these cases. Recent studies suggest that next-generation sequencing is useful in separating myelodysplasia cutis from true histiocytoid Sweet syndrome. This distinction has important implications for patients.

From Histiocytoid Sweet Syndrome to Myelodysplasia Cutis: History and Perspectives

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.

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.

Sweet Syndrome Associated with Myelodysplastic Syndrome—A Review of a Multidisciplinary Approach

Sweet syndrome (SS) is a rare disease described as a febrile neutrophilic dermatosis with acute onset, the pathogenesis of which has not yet been elucidated. The syndrome is characterized by the sudden onset of erythematous infiltrated papules or plaques located on the upper body and is associated with fever, leukocytosis and neutrophilia. The lesions show a dense dermal infiltration with mature neutrophils. The condition is responsive to systemic steroids. The central nervous system, bones, muscles, eyes, ears, mouth, heart, lung, liver, kidneys, intestines, and spleen may be affected by SS as extracutaneous manifestations. More and more cases have been found to be associated with malignancies, particularly myelodysplastic syndrome, and, less frequently, other hematologic malignancies or solid tumors. Approximately 21% of patients with SS have an associated malignancy and up to 80% of MASS cases are associated with hematological diseases, predominantly myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML). Myelodysplastic syndrome is a clonal disease of the bone marrow characterized by inefficient hematopoiesis, dysplasia of the bone marrow and peripheral cytopenias. Affected patients have a high risk of leukemic transformation. After analyzing later studies and current practical aspects regarding MDS-related SS, we suggest an algorithm for evaluating these patients.

Neonatal lupus erythematosus presenting as a non-bullous histiocytoid neutrophilic dermatosis

Histopathologic findings in neonatal lupus erythematosus (NLE) are usually congruent with those of subacute cutaneous lupus erythematosus. However, neutrophilic dermatosis-type histopathologic features are being increasingly recognized in the literature including rare cases with variant histiocytoid morphology. We report the case of a 7-week-old male presenting with figurate erythema. His mother was found to have elevated anti-nuclear antibodies and was positive for anti-SSA/Ro, anti-SSB/La antibodies and Ro52 autoantibodies. The infant had a similar serological profile. Skin biopsy showed a histiocytoid interstitial infiltrate with mild lichenoid features, sparse neutrophils and mild leukocytoclasis. The histiocytoid infiltrate showed prominent CD68, CD163, and myeloperoxidase expression. Isolated clusters of CD123⁺ histiocytes were also present. This case highlights the rare finding of non-bullous neutrophilic dermatosis with histiocytoid change in neonatal lupus. In neonates presenting with figurate erythemas with morphological histiocytic change on biopsy, NLE should be considered as a differential diagnosis and investigated for accordingly.

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.

Histiocytoid giant cellulitis-like Sweet syndrome at the site of sternal aspiration: A case report and review of literature

BACKGROUND

Giant cellulitis-like Sweet syndrome (SS) is a rare subtype of SS, and reports of the combined histiocytoid type of pathology are scarce. Here, we report a case of SS with distinctive clinical presentations and which was difficult to distinguish from cellulitis. By sharing this case and a discussion of the related literature in detail, we aim to provide clinicians with new insights into the characteristics of histiocytoid giant cellulitis-like (HGC)-SS and the pathogenesis of SS.

CASE SUMMARY

A 52-year-old male was admitted after experiencing progressive fatigue for 1 mo and tongue swelling with pain for 1 d. He was diagnosed with myelodysplastic syndrome (MDS) and angioneurotic edema of the tongue and floor of the mouth. However, 7 d after examination by sternal aspiration, a violaceous, tender, and swollen nodule developed at the site, with poorly demarcated erythema of the surrounding skin. Considering his profile of risk factors, the diagnosis of cellulitis was made and he was administered broad-spectrum antibiotics. When the lesion continued to worsen and he developed chills and fever, pathogenic and dermatopathological examination led to the diagnosis of HGC-SS. Treatment with prednisone led to the fever being relieved within 24 h and the skin lesion being resolved within 1 wk. The patient refused intensive treatment and was instead given thalidomide, erythropoietin, stanozolol, and supportive care. The prednisone was gradually tapered, with no signs of recurrence, but he died 2 mo later of severe pneumonia.

CONCLUSION

HGC-SS demonstrates unique manifestation. SS and leukemia cutis share cytological origin. Myelofibrosis and SS are adverse prognostic factors for MDS.

Drug-Induced Histiocytoid Sweet Syndrome: Two Cases With Levofloxacin and Amoxicillin-Clavulanate

ABSTRACT

Histiocytoid Sweet syndrome (HSS) is an uncommon histologic variant of Sweet syndrome (SS). HSS can be distinguished from the classic SS with an infiltrate of histiocyte-like immature myeloid cells rather than dense neutrophilic infiltration, although the clinical features are similar. Previous studies have shown that the risk of hematologic malignancy is significantly higher in HSS compared with classic SS. To lesser extent, HSS is also associated with infections, inflammatory diseases, and drugs, particularly with antineoplastic agents as well. Here, we report a case of 2 patients with an abrupt onset of erythematous, tender plaques accompanied by fever, with that revealed similar histopathologic and immunohistochemical features, whom had a history of antibiotic use. Clinicopathologic correlation led to diagnosis of drug-induced HSS, associated with the use of levofloxacin and amoxicillin-clavulanate, respectively. Both patients were then successfully treated with systemic corticosteroid therapy, and neither of them had recurrence during the period of 24-month follow-up.

Neutrophilic Dermatoses: a Clinical Update

Purpose of Review

Neutrophilic dermatoses are defined by the presence of a sterile neutrophilic infiltrate on histopathology. This review focuses on the pathogenesis, epidemiology, clinicopathological features, diagnosis, and management of four disorders: Sweet syndrome, pyoderma gangrenosum, Behçet syndrome, and neutrophilic eccrine hidradenitis.

Recent Findings

Recent studies have provided insight into the complex pathogenesis of neutrophilic dermatoses. Evidence supports an intricate interplay of abnormal neutrophil function and inflammasome activation, malignant transformation into dermal infiltrating neutrophils, and genetic predisposition.

Summary

Neutrophilic dermatoses have diverse cutaneous and extracutaneous manifestations and may be associated with significant morbidity and mortality. Common underlying associations include infectious, inflammatory, and neoplastic disorders, as well as drug reactions. Emerging diagnostic and therapeutic frameworks identify an expanding role for biologic and targeted anti-inflammatory therapies.

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.

VEXAS within the spectrum of rheumatologic disease

The identification of the VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) syndrome as a myeloid-driven inflammatory disease resulting from somatic mutations in the UBA1 gene further exposes the increasingly recognized overlap between hematologic disturbances and auto-immunity and/or auto-inflammatory presentations. Although single or multi-lineage cytopenias are a unifying aspect of VEXAS, patients with this condition can present with a wide array of inflammatory findings affecting the skin, lung, joints, eye, vascular system, and cartilaginous structures. As such, it is paramount that generalists, and subspecialty providers familiarize themselves with the clinical characteristics of this condition. This review summarizes the reported clinical symptoms of VEXAS syndrome with a particular focus on its non-hematologic inflammatory features.

Systematic Review: Sweet Syndrome Associated with Inflammatory Bowel Disease

BACKGROUND AND AIMS

Sweet syndrome [SS] is a dermatological condition associated with both inflammatory bowel disease [IBD] and azathioprine use. We performed a systematic review to better delineate clinical characteristics and outcomes of SS in IBD patients.

METHODS

Peer-reviewed, full-text journal publications from inception to April 2020 in English language and adult subjects with IBD were included. Skin biopsy was required as SS gold-standard diagnosis. Azathioprine-associated SS required recent azathioprine introduction or recurrence of SS after azathioprine re-challenge.

RESULTS

We included 89 publications with 95 patients [mean age of SS diagnosis: 44 years; 59% female; 20 with azathioprine-associated SS and 75 without]. SS was diagnosed prior to IBD in 5.3%, at time of IBD diagnosis in 29.5% and after diagnosis in 64.2%. In total, 91% of patients with SS had known colonic involvement and the majority [76%] had active IBD at diagnosis; 22% had additional extra-intestinal manifestations. Successful therapies for SS included corticosteroids [90.5%], anti-tumour necrosis factor [TNF]-α inhibitor therapy [14.8%] and azathioprine [11.6%]. Azathioprine-associated SS was distinct, with 85% male patients, mean age of SS diagnosis of 50 years and a lower likelihood to be prescribed corticosteroids for treatment [75% vs 94.7% of non-azathioprine-associated SS, p = 0.008]. All patients with azathioprine-associated SS improved with medication cessation and developed recurrence after re-challenge.

CONCLUSIONS

SS may precede or occur with IBD diagnosis in almost one-third of cases. Azathioprine and IBD-associated SS present and behave distinctly, especially with regard to gender, age at diagnosis and recurrence risk. Corticosteroids and TNF-α inhibitors have demonstrated efficacy in treating SS in IBD.

UBA1 Variations in Neutrophilic Dermatosis Skin Lesions of Patients With VEXAS Syndrome

Importance

VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) is a recently described severe adult-onset autoinflammatory disease that is associated with myeloid lineage-restricted ubiquitin-activating enzyme 1 (UBA1) somatic variations that primarily affect the skin (Sweet syndrome), cartilage, and bone marrow. Skin symptoms have been poorly described.

Objective

To better describe clinical and pathological skin manifestations and their pathophysiology in VEXAS syndrome.

Design, Setting, and Participants

This multicenter retrospective case series study of clinical and histological features of 8 patients with VEXAS syndrome and skin involvement was conducted in France from December 2007 to March 2021, with molecular data obtained from March to April 2022. Any UBA1 variations were detected by Sanger or next-generation sequencing that was performed on bone marrow and formalin-fixed paraffin-embedded tissue sections of skin lesion biopsies.

Results

All 8 patients were men, and the median age at symptom onset was 65.5 years (interquartile range, 54-76 years). All patients had neutrophilic dermatosis skin lesions, including tender red or violaceous papules, sometimes edematous, without fever, arthralgia, recurrence or pathergy, inflammatory edematous papules on the neck and trunk (sometimes umbilicated), and firm erythematous purpuric or pigmented infiltrated plaques and nodules. Three patients had livedo racemosa. The infiltrates were perivascular and consisted of mature neutrophils with leukocytoclasia, which were admixed with myeloperoxidase-positive CD163-positive myeloid cells with indented nuclei and lymphoid cells in all cases. A sequencing analysis of paired bone marrow samples and skin lesion biopsies identified the same loss-of-function UBA1 variation in both samples for all patients.

Conclusions and Relevance

This case series study describes the different clinical presentations of skin lesions found in VEXAS syndrome, which is characterized histologically by neutrophilic dermatosis. The findings suggested that the dermal infiltrates seen in VEXAS skin lesions are derived from the pathological myeloid clone. This suggests that using therapies that target the pathological clone may be effective in the long-term management of the disease.

Sweet's Syndrome in a Patient With Seropositive Rheumatoid Arthritis After Starting Adalimumab: Is Sweet's Syndrome Related to Rheumatoid Arthritis or Is It the Paradoxical Effect of Adalimumab?

Sweet’s syndrome is a rare acute febrile neutrophilic dermatosis accompanied by fever, neutrophilia, and asymmetrical distribution of tender erythematous skin lesions. The underlying biological pathways responsible for this inflammatory skin disorder are not yet clearly established. However, an association with autoimmune disease, neoplasm, and drugs could be indicative of unusual hypersensitivity involving proinflammatory cytokines. There are several case reports indicating an association between Sweet’s syndrome and rheumatoid arthritis (RA). Proinflammatory cytokines are considered to play a vital role in the pathogenesis of both RA and Sweet’s syndrome. Adalimumab works against proinflammatory cytokines and is considered a disease-modifying antirheumatic drug in RA; it is also reported to be effective in refractory Sweet’s syndrome. While adalimumab has been proven to be beneficial in autoimmune disorders and inflammatory conditions, there are also reports of paradoxical development of Sweet’s syndrome with adalimumab. In this report, we present a case of Sweet’s syndrome in a 74-year-old adult patient with a history of seropositive RA who developed Sweet’s syndrome within two months after the initiation of adalimumab therapy.

The combined prevalence of classified rare rheumatic diseases is almost double that of ankylosing spondylitis

BACKGROUND

Rare diseases (RDs) affect less than 5/10,000 people in Europe and fewer than 200,000 individuals in the United States. In rheumatology, RDs are heterogeneous and lack systemic classification. Clinical courses involve a variety of diverse symptoms, and patients may be misdiagnosed and not receive appropriate treatment. The objective of this study was to identify and classify some of the most important RDs in rheumatology. We also attempted to determine their combined prevalence to more precisely define this area of rheumatology and increase awareness of RDs in healthcare systems. We conducted a comprehensive literature search and analyzed each disease for the specified criteria, such as clinical symptoms, treatment regimens, prognoses, and point prevalences. If no epidemiological data were available, we estimated the prevalence as 1/1,000,000. The total point prevalence for all RDs in rheumatology was estimated as the sum of the individually determined prevalences.

RESULTS

A total of 76 syndromes and diseases were identified, including vasculitis/vasculopathy (n = 15), arthritis/arthropathy (n = 11), autoinflammatory syndromes (n = 11), myositis (n = 9), bone disorders (n = 11), connective tissue diseases (n = 8), overgrowth syndromes (n = 3), and others (n = 8). Out of the 76 diseases, 61 (80%) are classified as chronic, with a remitting-relapsing course in 27 cases (35%) upon adequate treatment. Another 34 (45%) diseases were predominantly progressive and difficult to control. Corticosteroids are a therapeutic option in 49 (64%) syndromes. Mortality is variable and could not be determined precisely. Epidemiological studies and prevalence data were available for 33 syndromes and diseases. For an additional eight diseases, only incidence data were accessible. The summed prevalence of all RDs was 28.8/10,000.

CONCLUSIONS

RDs in rheumatology are frequently chronic, progressive, and present variable symptoms. Treatment options are often restricted to corticosteroids, presumably because of the scarcity of randomized controlled trials. The estimated combined prevalence is significant and almost double that of ankylosing spondylitis (18/10,000). Thus, healthcare systems should assign RDs similar importance as any other common disease in rheumatology.

Inflammatory and Immune Disorders Associated with Myelodysplastic Syndromes

Systemic auto-inflammatory or autoimmune diseases (SIADs) develop in up to a quarter of patients with myelodysplastic syndromes (MDS) or chronic myelomonocytic leukemia (CMML). With or without the occurrence of SIADs, the distribution of MDS subtypes and the international or CMML-specific prognostic scoring systems have been similar between MDS/CMML patients. Moreover, various SIADs have been described in association with MDS, ranging from limited clinical manifestations to systemic diseases affecting multiple organs. Defined clinical entities including systemic vasculitis, connective tissue diseases, inflammatory arthritis and neutrophilic diseases are frequently reported; however, unclassified or isolated organ impairment can also be seen. Although the presence of SIADs does not impact the overall survival nor disease progression to acute myeloid leukemia, they can help with avoiding steroid dependence and make associated adverse events of immunosuppressive drugs challenging. While therapies using steroids and immunosuppressive treatment remain the backbone of first-line treatment, increasing evidence suggests that MDS specific therapy (hypomethylating agents) and sparing steroids may be effective in treating such complications based on their immunomodulatory effect. The aim of this review was to analyze the epidemiological, pathophysiological, clinical and therapeutic factors of systemic inflammatory and immune disorders associated with MDS.

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.

Sweet's syndrome associated with hematological malignancies

BACKGROUND

Sweet's syndrome, or acute febrile neutrophilic dermatosis, is often mistaken for a skin infection given its similar clinical presentation.

OBJECTIVE

To describe the clinical presentations and management of a rare dermatologic condition associated with hematological malignancies.

METHODS

Case series; Chart review of patients at Moffitt Cancer Center between 2017 and 2020.

RESULTS

The subjects are a 79 year-old man (Patient 1) with Myelodysplastic Syndrome (MDS), a 66 year-old woman (Patient 2) with Acute Myeloid Leukemia (AML), a 56 year-old man (Patient 3) with AML, and a 69 year-old man (Patient 4) with MDS. Patient 1 was initially misdiagnosed with neutropenic fever. Patient 2 was incidentally discovered to have erythematous skin lesions prior to initiating chemotherapy. Before starting second line chemotherapy, patient 3 developed pathergy at the site of a PICC line. Patient 4 developed erythema around a newly placed port before initiating chemotherapy. Only patients 1 and 3 received glucocorticoids. Patients 2, 3, and 4 were able to initiate chemotherapy without further complications.

LIMITATIONS

Heterogeneity of subjects in terms of prognostic factors, stage at diagnosis, and treatment strategies.

CONCLUSION

Early recognition and treatment of malignancy-associated Sweet's syndrome is imperative to limit patient morbidity and expeditiously provide anti-cancer treatments.

Insights Into the Characteristics of Sweet Syndrome in Patients With and Without Hematologic Malignancy

Background: Sweet syndrome is a neutrophilic dermatosis that could be associated with malignancy, especially hematologic malignancy. Few studies have systematically elaborated on this disorder and its features related with hematologic malignancy. Objective: This study aimed to describe the clinicopathological characteristics, treatment, and outcome of Sweet syndrome and to evaluate patient characteristics associated with hematologic malignancy. Methods: We retrospectively reviewed patients with Sweet syndrome at the Department of Dermatology, the First Affiliated Hospital of Zhejiang University from October 2010 to February 2019. Results: The study included 37 patients (16 men and 21 women), with a mean age of 53 years. Ten patients (27%) were classified as having malignancy-associated Sweet syndrome: nine with a hematologic malignancy including acute myeloid leukemia (4/9, 44%), myelodysplastic syndrome (4/9, 44%), and multiple myeloma (1/9, 11%) and one with a solid tumor diagnosed with liver carcinoma. The mean hemoglobin and platelet levels (P = 0.007 and P = 0.013, respectively), were significantly lower in patients with hematologic malignancy than in those with Sweet syndrome only. No significant difference in histopathology was found between patients with and without hematologic malignancy. Systemic corticosteroids were the most frequently used treatment (24/37, 65%). Higher mortality was found in patients with hematologic malignancy. Conclusion: It is important to assess Sweet syndrome patients who have laboratory evidence of lower hemoglobin and platelet levels for a hematologic malignancy.

Recurrent Idiopathic Sweet Syndrome - Case Report and Literature Review

INTRODUCTION

Sweet syndrome (SS), also denominated as acute febrile neutrophilic dermatosis, is a rare disease characterized by the sudden onset of painful, erythematous, firm skin lesions (papules, plaques, and nodules) which show, upon histologic examination, the presence of a diffuse infiltrate of mature neutrophils. The cutaneous manifestation typically involves the face, neck, trunk, and upper limbs and is associated with fever, general malaise, arthralgia.

CASE REPORT

A female patient, 60 years old, attended the Dermatology Clinic due to the appearance of violaceous erythematous-oedematous infiltrated plaques, located on the face, neck, upper limbs, trunk and knees. The onset of the cutaneous manifestation had occurred 2 months prior, accompanied by pain, chills, flares of fever and arthralgia. The onset coincided with the surgical treatment of an umbilical hernia. From the medical history we note that the patient was diagnosed in 2014 with histiocytoid SS. She followed a treatment with methylprednisolone, with positive response, but had many relapses after the discontinuation of treatment. In 2017, due to a new episode, the histopathological examination was repeated, which revealed classical SS. She received treatment with Disulone and Colchicine. She had not been administered any treatment throughout the previous year. Laboratory tests revealed leukocytosis with neutrophils, increased ESR, elevated C4, hyperglycemia. The current histopathological examination revealed lymphocytic SS. Under treatment with methylprednisolone 32mg/day, the evolution was favorable.

DISCUSSIONS

The first case of SS was described by Robert Douglas Sweet in 1964. As known aetiological factors there have been described gastrointestinal and urinary tract infections, pregnancy, inflammatory bowel disease, drugs or malignancies. There have been described cases of SS that appeared after surgical treatment, as in our case, which registered a new outbreak following the umbilical hernia treatment. The histopathological variants of SS described in the literature are: subcutaneous, eosinophilic, histiocytoid, lymphocytic type. The first line-therapy consists in systemic corticosteroids, which induce a fast remission of lesions and general symptoms. Recurrence may occur in approximately 50% of patients and is common in idiopathic or paraneoplastic cases.

CONCLUSIONS

In addition to the neutrophilic infiltrate that is typical for Sweet syndrome, different types of histological manifestations have been described in the literature: subcutaneous, eosinophilic, histiocytoid, lymphocytic. In our case, we noted that the histological profile changed over time, from a histiocytoid SS recorded in 2014, to a classical SS in 2017, followed by the appearance of lymphocytic SS in 2019. Due to the fact that SS can be associated with a numerous other disorders, our patient requires regular monitoring with a view to eliminate them, and potentially to make a diagnosis and initiate early specific treatment.

Superficial and Deep Cutaneous Involvement by RAS-Associated Autoimmunne Leukoproliferative Disease (RALD Cutis): A Histologic Mimicker of Histiocytoid Sweet Syndrome

RAS-associated autoimmune leukoproliferative disease (RALD) is a recently described noninfectious and nonmalignant clinical syndrome characterized by autoimmune disorders, massive splenomegaly, modest lymphadenopathy, and monocytosis. On the molecular level, RALD is defined by somatic mutations of either NRAS or KRAS gene in a subset of hematopoietic cells. To date, there is a dearth of well-documented histopathologic description of cutaneous involvement by RALD in the literature. In the current case report, a 43-year-old female patient with a history of RALD presented with clinical pictures of sepsis and an erythematous rash in the left lower extremity. Histologic examination revealed a dense perivascular and interstitial infiltrate of immature myeloid cells admixed with scattered neutrophils involving the dermis and subcutaneous adipose tissue, imparting a panniculitis-like histologic pictures. There was a strong angiocentric propensity of the immature hematopoietic cells as well as extensive extravasation of red blood cells, even in the subcutaneous adipose tissue. Immunohistochemically, the immature hematopoietic cells were positive for CD43, CD4, and CD68, but negative for CD34, CD117, and myeloperoxidase. Overall, the histologic and cytologic findings were highly reminiscent of histiocytoid Sweet syndrome. Review of the English literature revealed cutaneous involvements by RALD only in patients with KRAS mutation compared with none of its NRAS counterparts. However, larger clinicopathologic studies on cutaneous involvement by RALD are warranted. The term "RALD cutis" with its histologic and molecular features is suggested to serve as a potential groundwork for future studies of this rare phenomenon.

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.

Dermatologic Urgencies and Emergencies: What Every Pathologist Should Know

CONTEXT.—

Fatal dermatologic diseases and ones with high morbidity can occur in the inpatient setting. In such cases, prompt and accurate assessment of a bedside skin biopsy is required. This may be challenging for many pathologists who are not familiar with the complexity of skin pathology and skin terminology within the fields of dermatopathology and dermatology.

OBJECTIVE.—

To provide the pathologist with a practical, up-to-date, and "must-know" reference guide on dermatologic urgencies and emergencies from a real-world perspective, highlighting diagnostic pearls, diagnostic pitfalls, and commonly encountered practice gaps. This review will focus on key diseases with which every pathologist should be familiar, including angioinvasive fungal infections, Stevens-Johnson syndrome/toxic epidermal necrolysis, staph-scalded-skin syndrome, acute graft-versus-host disease, bullous pemphigoid, calciphylaxis, Sweet syndrome and its histiocytoid variant, pyoderma gangrenosum, and leukocytoclastic vasculitis, as well as those in their clinical and histopathologic differential.

DATA SOURCES.—

This review is based on peer-reviewed literature and our personal experiences with these diseases at major academic institutions, including one where a large number of stem cell transplants are performed. This review is unique as it represents collaborative expert opinion from both a dermatopathology and a dermatology standpoint.

CONCLUSIONS.—

This review outlines the critical role that the pathologist plays in the outcomes of patients with dermatologic urgencies and emergencies. Improved patient care will result from prompt and accurate histopathologic diagnoses as well as an open line of communication with the dermatologist.

What's New in Dermatopathology: Inflammatory Dermatoses

Inflammatory skin diseases encompass a vast array of conditions. The field continues to expand and evolve with resurgence of conditions, through newly recognized medication adverse effects, and via more detailed descriptions of known dermatoses. The importance of clinicopathologic correlation and an up to date knowledge of dermatologic conditions cannot be overstated. This review focuses on an array of recent important developments in the histologic diagnosis of inflammatory conditions that affect the skin.

Neutrophilic dermatoses: Pathogenesis, Sweet syndrome, neutrophilic eccrine hidradenitis, and Behçet disease

Neutrophilic dermatoses are a heterogeneous group of inflammatory skin disorders that present with unique clinical features but are unified by the presence of a sterile, predominantly neutrophilic infiltrate on histopathology. The morphology of cutaneous lesions associated with these disorders is heterogeneous, which renders diagnosis challenging. Moreover, a thorough evaluation is required to exclude diseases that mimic these disorders and to diagnose potential associated infectious, inflammatory, and neoplastic processes. While some neutrophilic dermatoses may resolve spontaneously, most require treatment to achieve remission. Delays in diagnosis and treatment can lead to significant patient morbidity and even mortality. Therapeutic modalities range from systemic corticosteroids to novel biologic agents, and the treatment literature is rapidly expanding. The first article in this continuing medical education series explores the pathogenesis of neutrophilic dermatoses and reviews the epidemiology, clinical and histopathologic features, diagnosis, and management of Sweet syndrome, neutrophilic eccrine hidradenitis, and Behçet disease.

Lymphocytes in Sweet syndrome: A potential diagnostic pitfall

BACKGROUND

Patients with Sweet syndrome (SS) have acute onset of cutaneous lesions with characteristic histopathology (dense and diffuse neutrophilic infiltrate, dermal edema, leukocytoclasis and no vasculitis) accompanied by systemic symptoms. Sometimes, only skin lesions with classic histopathologic features are seen. Although SS is considered to be a "neutrophilic dermatosis," lymphocytes are also seen on histological examination.

METHODS

We evaluated the cellular infiltrate in 9 biopsies from SS lesions with routine staining and immunohistochemistry.

RESULTS

Lymphocytes were present in all biopsies in variable amounts, often exceeding the number of intact neutrophils. Prominent fragmentation of neutrophils rendered some biopsies "lymphocyte-rich" on routine histologic evaluation. Myeloperoxidase was helpful in highlighting the inconspicuous neutrophilic fragments in these cases. Lymphocytes were highlighted with immunohistochemistry, and had a CD3+, CD4+, CD20(-) immunophenotype, with rare CD8+ lymphocytes.

CONCLUSION

Awareness of the lymphocytic component of SS is important to avoid diagnostic errors, especially in subcutaneous lesions of SS, in which the lymphocytic infiltrate predominates in the upper parts of the dermis, while the typical neutrophilic infiltrate may be seen only in the deeper dermis and subcutis. The lymphocytic component may potentially help to differentiate lesions of SS from neutrophilic urticarial dermatosis, which has not been reported to contain a significant lymphocytic population.

Sweet syndrome in patients with and without malignancy: A retrospective analysis of 83 patients from a tertiary academic referral center

BACKGROUND

Sweet syndrome is a neutrophilic dermatosis that may be categorized into classic, malignancy-associated, and drug-induced subtypes. Few studies have systematically analyzed this rare disorder.

OBJECTIVE

To describe the clinicopathologic characteristics and treatment of Sweet syndrome and identify characteristics associated with concurrent malignancy.

METHODS

We retrospectively reviewed patients with Sweet syndrome at the University of Pennsylvania from 2005 to 2015.

RESULTS

We identified 83 patients (mean age, 57 years; 51% male) with Sweet syndrome: 30% with the classic form, 44% with the malignancy-associated form, 24% with the drug-induced form in the setting of malignancy, and 2% with the drug-induced form. Acute myeloid leukemia was the most common malignancy (in 24 of 83 patients [29%]). Filgrastim was the most common medication (used in 8 of 83 patients [10%]). Leukopenia (P < .001), anemia (P = .002), thrombocytopenia (P < .001), absence of arthralgia (P < .001), and histiocytoid or subcutaneous histopathology (P = .024) were associated with malignancy (χ² test).

LIMITATIONS

This was a retrospective study that represents patients from a single tertiary academic referral center, which may limit its generalizability to other settings.

CONCLUSION

When caring for patients with Sweet syndrome, dermatologists should be aware of the potential association of leukopenia, anemia, thrombocytopenia, absence of arthralgia, and histiocytoid or subcutaneous histopathology with malignancy.

Clinicopathologic, Immunohistochemical, and Molecular Features of Histiocytoid Sweet Syndrome

Importance

Histiocytoid Sweet syndrome is a rare histopathologic variant of Sweet syndrome. The nature of the histiocytoid infiltrate has generated considerable controversy in the literature.

Objective

The main goal of this study was to conduct a comprehensive overview of the immunohistochemical phenotype of the infiltrate in histiocytoid Sweet syndrome. We also analyze whether this variant of Sweet syndrome is more frequently associated with hematologic malignancies than classic Sweet syndrome.

Design

This is a retrospective case series study of the clinicopathologic, immunohistochemical, and molecular features of 33 patients with a clinicopathologic diagnosis of histiocytoid Sweet syndrome was conducted in the dermatology departments of 5 university hospitals and a private laboratory of dermatopathology.

Main Outcome and Measures

The clinical, histopathological, immunohistochemical, and follow-up features of 33 patients with histiocytoid Sweet syndrome were analyzed. In some cases, cytogenetic studies of the dermal infiltrate were also performed. We compare our findings with those of the literature.

Results

The dermal infiltrate from the 33 study patients (20 female; median age, 49 years; age range, 5-93 years; and 13 male; median age, 42 years; age range, 4-76 years) was mainly composed of myeloperoxidase-positive immature myelomonocytic cells with histiocytoid morphology. No cytogenetic anomalies were found in the infiltrate except in 1 case in which neoplastic cells of chronic myelogenous leukemia were intermingled with the cells of histiocytoid Sweet syndrome. Authentic histiocytes were also found in most cases, with a mature immunoprofile, but they appeared to be a minor component of the infiltrate. Histiocytoid Sweet syndrome was not more frequently related with hematologic malignancies than classic neutrophilic Sweet syndrome.

Conclusions and Relevance

The dermal infiltrate of cutaneous lesions of histiocytoid Sweet syndrome is composed mostly of immature cells of myeloid lineage. This infiltrate should not be interpreted as leukemia cutis.