[Idiopathic pustular and bullous variants of Sweet syndrome]

Neutrophilic Dermatosis and Management Strategies for the Inpatient Dermatologist

Purpose of Review

Neutrophilic dermatoses are a heterogeneous group of disorders with significant overlap in associated conditions, clinical presentation, and histopathologic features. This review provides a structural overview of neutrophilic dermatoses that may present in the inpatient setting along with diagnostic work-up and management strategies.

Recent Findings

Sweet’s syndrome has been found in patients with coronavirus disease 2019 (COVID-19). Pyoderma gangrenosum (PG) has been shown to be equally associated with ulcerative colitis and Crohn’s disease. A clinical trial shows that cyclosporine is equally effective as prednisone in treating PG. Neutrophilic eccrine hidradenitis has been found in the setting of newer antineoplastic medications, such as BRAF inhibitors, as well as in the setting of malignancy without chemotherapy exposure.

Summary

Neutrophilic dermatoses are a rare and complex group of dermatoses with varying and overlapping clinical presentations. Physicians should be aware of the growing list of associated diseases in order to build a better differential diagnosis or to potentially investigate for co-existing disease.

Autoinflammatory Disorders: A Review and Update on Pathogenesis and Treatment

The autoinflammatory diseases comprise a broad spectrum of disorders characterized by unchecked activation of the innate immune system. Whereas aberrations in adaptive immunity have long been identified in 'autoimmune' disorders, the concept of 'autoinflammation' emerged relatively recently, first describing a group of clinical disorders characterized by spontaneous episodes of systemic inflammation without manifestations typical of autoimmune disorders. Improved knowledge of innate immune mechanisms, coupled with remarkable progress in genomics and an expanding number of clinical cases, has since led to an increasing number of disorders classified as autoinflammatory or containing an autoinflammatory component. Biologic therapies targeting specific components of the innate immune system have provided immense clinical benefit, and have further elucidated the role of innate immunity in autoinflammatory disorders. This article reviews the basic mechanisms of autoinflammation, followed by an update on the pathophysiology and treatment of the monogenic and multifactorial autoinflammatory diseases, and the common dermatologic conditions in which autoinflammation plays a major role.

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.

Sweet's syndrome in a patient with chronic lymphocytic leukaemia

Bullous Sweet's syndrome is a rare variant of the inflammatory neutrophilic dermatosis characterised by painful bullous skin lesions, fever, leukocytosis and a neutrophilic infiltrate of the dermis. The condition may be classified according to aetiology into classical (idiopathic), malignancy-associated and drug-induced. Neutrophilic infiltration occurs in response to a systemic insult. A punch biopsy for histology and culture is necessary due to its close resemblance to infection. Characteristic histology features a dense infiltration of neutrophils in the upper and mid dermis, oedema in the superficial dermis and endothelial swelling. Treatment with systemic glucocorticosteroids typically results in a dramatic clinical response. This case report illustrates a rare case of bullous Sweet syndrome associated with chronic lymphocytic leukaemia in a 53-year-old man.

[Sweet's syndrome with bullous lesions]

We present a case of Sweet's syndrome with atypical lesions, characterized by erythematous plaques, vesicles and bullous lesions. Skin lesions in patients with an underlying malignancy are more frequently atypical and with vesicular, bullous or even ulcerative characteristics, in addition to the typical plaques and nodules. However, the case presented is not associated with malignancy, despite the fact that these processes, particularly hematologic ones, should be suspected.

Sweet syndrome in two children

We report a 9-month-old girl and a 4-year-old boy with acute febrile neutrophilic dermatosis (Sweet syndrome). Both children were febrile, had leukocytosis, and exhibited lesions characteristic of Sweet syndrome. Both had an antecedent infection. Our evaluation and long-term follow-up of these children failed to reveal evidence of underlying malignancy or a chronic systemic illness typically encountered in Sweet syndrome. Of interest, the 4-year-old boy responded to systemic corticosteroids with remission, whereas the 9-month-old infant experienced flaring of the disease on successive attempts to taper the systemic corticosteroids. Systemic corticosteroid usage was associated with alteration in behavior in the 4-year-old and transient growth retardation in the 9-month-old. In both patients, the adverse effects resolved after discontinuation of the corticosteroids.

Sweet's syndrome (acute febrile neutrophilic dermatosis)

Acute febrile neutrophilic dermatosis, first described in 1964 by Robert Douglas Sweet, has been termed Sweet's syndrome. Classic Sweet's syndrome occurs in middle-aged women after a nonspecific infection of the respiratory or gastrointestinal tract. Raised erythematous plaques with pseudoblistering and occasionally pustules occur on the face, neck, chest, and extremities, accompanied by fever and general malaise. Involvement of the eyes, joints, and oral mucosa as well as internal manifestations of Sweet's syndrome in the lung, liver, kidneys, and central nervous system has been described. The disease is thought to be a hypersensitivity reaction. Parainflammatory (e.g., infections, autoimmune disorders, vaccination) and paraneoplastic (e.g., hemoproliferative disorders, solid malignant tumors) occurrence is found in approximately 25% of the cases and 2% are associated with pregnancy. Sweet's syndrome responds rapidly to systemic therapy with corticosteroids but recurs in about 25% of the cases. Alternative treatment modalities (e.g., potassium iodide, colchicine, dapsone, clofazimine, cyclosporine) have also been used. This article presents data from 38 patients with Sweet's syndrome and reviews its epidemiology, clinical spectrum, histologic features, laboratory results, differential diagnosis, pathogenic mechanisms, associated diseases, and treatment.