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Acute Febrile Neutrophilic Dermatosis

(Sweet Syndrome)


Julia Benedetti

, MD, Harvard Medical School

Last full review/revision Jul 2020| Content last modified Jul 2020
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Acute febrile neutrophilic dermatosis is characterized by tender, indurated, dark-red papules and plaques with prominent edema in the upper dermis and dense infiltrate of neutrophils. The cause is not known. It frequently occurs with underlying cancer, especially hematologic cancers. Diagnosis is usually with skin biopsy. Treatment is systemic corticosteroids or, alternatively, colchicine or potassium iodide.


Acute febrile neutrophilic dermatosis may occur with various disorders. It is often classified into 3 categories:

  • Classical

  • Cancer-associated

  • Drug-induced


About 25% of patients have an underlying cancer, 75% of which are hematologic cancers, especially myelodysplastic syndromes Myelodysplastic Syndrome (MDS) The myelodysplastic syndrome (MDS) is group of disorders typified by peripheral cytopenia, dysplastic hematopoietic progenitors, a hypercellular or hypocellular bone marrow, and a high risk... read more and acute myelogenous leukemia Acute Myeloid Leukemia (AML) In acute myeloid leukemia (AML), malignant transformation and uncontrolled proliferation of an abnormally differentiated, long-lived myeloid progenitor cell results in high circulating numbers... read more Acute Myeloid Leukemia (AML) . Classical acute febrile neutrophilic dermatosis affects mostly women ages 30 to 50, with a female:male ratio of 3:1. In contrast, men who develop the condition tend to be older (60 to 90). In children under age 3, the ratio is male:female 2:1.

The cause of acute febrile neutrophilic dermatosis is unknown; however, type 1 helper T-cell cytokines, including interleukin-2 and interferon-gamma, are predominant and may play a role in lesion formation.

Symptoms and Signs

Patients are febrile, with an elevated neutrophil count, and have painful, tender, and edematous dark-red plaques or papules, most often on the face, neck, and upper extremities, especially the dorsum of hands. Oral lesions can also occur. The lesions often develop in crops and may appear annular. Each crop is usually preceded by fever and persists for days to weeks. Rarely, bullous and pustular lesions are present as well.

Less common variants include a bullous form that can ulcerate and resemble pyoderma gangrenosum and a subcutaneous form involving the subcutaneous fat that typically has 2- to 3-cm erythematous nodules, commonly affecting the extremities. When on the lower extremities, this form can resemble erythema nodosum Erythema Nodosum Erythema nodosum is a specific form of panniculitis characterized by tender, red or violet, palpable, subcutaneous nodules on the shins and occasionally other locations. It often occurs with... read more Erythema Nodosum .

Extracutaneous manifestations are rare and can involve the eyes (eg, conjunctivitis, episcleritis, iridocyclitis), joints (eg, arthralgia, myalgia, arthritis), and internal organs (eg, neutrophilic alveolitis; sterile osteomyelitis; psychiatric or neurologic changes; transient kidney, liver, and pancreatic insufficiency).


  • Clinical evaluation

  • Skin biopsy

If the diagnosis is unclear, skin biopsy Biopsy Diagnostic tests are indicated when the cause of a skin lesion or disease is not obvious from history and physical examination alone. These include Patch testing Biopsy Scrapings Examination... read more Biopsy should be done. The histopathologic pattern is that of edema in the upper dermis with a dense infiltrate of neutrophils in the dermis. Vasculitis may be present but is secondary.


  • Corticosteroids

Treatment of acute febrile neutrophilic dermatosis involves systemic corticosteroids, chiefly prednisone 0.5 to 1.5 mg/kg orally once a day tapered over 3 weeks. Colchicine 0.5 mg orally 3 times a day or potassium iodide 300 mg orally 3 times a day are alternative treatments. Antipyretics are also recommended.

In difficult cases, dapsone 100 to 200 mg orally once a day, indomethacin 150 mg orally once a day for 1 week and 100 mg orally once a day for 2 additional weeks, clofazimine (eg, 200 mg orally once a day for 4 weeks then 100 mg/day for 4 weeks), or cyclosporine (eg, 2 to 4 mg/kg orally 2 times a day) can be given. Other treatments used for refractory disease include infliximab, etanercept, thalidomide, minocycline, and mycophenolate mofetil.

For localized involvement, intralesional corticosteroids (eg, triamcinolone acetonide) may help.

Key Points

  • Acute febrile neutrophilic dermatosis can occur in patients who have certain disorders (classical form) or take certain drugs (drug-induced form), but about 25% of patients have an underlying cancer (cancer-associated form), usually a hematologic cancer.

  • Diagnose acute febrile neutrophilic dermatosis based on the appearance of the lesions and presence of an associated disorder or drug, and confirm with biopsy when necessary.

  • Treat most patients with systemic corticosteroids or, alternatively, colchicine or potassium iodide.

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