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Acute Febrile Neutrophilic Dermatosis

(Sweet Syndrome)

by Wingfield E. Rehmus, MD, MPH

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.


Acute febrile neutrophilic dermatosis may occur with various disorders. It is often classified into 3 categories: classical, malignancy-associated, and drug-induced.

Disorders and Drugs Associated with Acute Febrile Neutrophilic Dermatosis




Acute respiratory illness

GI infection

Inflammatory and autoimmune disorders



Acute myeloid leukemia

Myelodysplastic syndromes


Granulocyte colony-stimulating factor (G-CSF, the most common drug cause)



Others (eg, abacavir, furosemide, hydralazine, NSAIDs, oral contraceptives, retinoids)

About 25% of patients have an underlying cancer, 75% of which are hematologic cancers, especially myelodysplastic syndromes and acute myeloid leukemia. 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).

The cause is unknown; however, type 1 helper T-cell cytokines, including IL-2 and interferon-γ, are predominant and may play a role in lesion formation.

Symptoms and Signs

Patients are febrile, with an elevated neutrophil count, and have tender, dark-red plaques or papules, most often on the face, neck, and upper extremities, especially the dorsum of hands. Oral lesions can also occur. Rarely, bullous and pustular lesions are present. The lesions often develop in crops and may appear annular. Each crop is preceded by fever and persists for days to weeks. Acute febrile neutrophilic dermatosis resulting from a hematologic cancer can cause a subcutaneous form, typically with 2- to 3-cm erythematous nodules, commonly involving the extremities. When on the lower extremities, this form can resemble erythema nodosum.

Extracutaneous manifestations 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

Diagnosis is suggested by the appearance of the lesions and is supported by the presence of associated conditions or drugs. Differential diagnosis can include erythema multiforme, erythema elevation diutinum, acute cutaneous lupus erythematosus, pyoderma gangrenosum, and erythema nodosum. If diagnosis is unclear, skin 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 involves systemic corticosteroids, chiefly prednisone 0.5 to 1.5 mg/kg po once/day tapered over 3 wk. Colchicine 0.5 mg po tid or K iodide 300 mg po tid are alternative treatments. Antipyretics are also recommended. In difficult cases, dapsone 100 to 200 mg po once/day, indomethacin 150 mg po once/day for 1 wk and 100 mg po once/day for 2 additional wk, clofazimine (eg, 200 mg po once/day for 4 wk then 100 mg/day for 4 wk), or cyclosporine (eg, 2 to 4 mg/kg po bid) can be given. 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 (malignancy-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 K iodide.

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