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Sweet’s Syndrome (Acute Febrile Neutrophil Dermatosis)

Key Points

  • Indurated, often painful, erythematous nodules are the characteristic skin lesion that marks Sweet’s syndrome. Skin lesions may be bullous or cellulitis-like (pseudocellulitic) in appearance.
  • Skin lesions of Sweet’s syndrome are often accompanied by signs of systemic inflammation: fever, malaise, arthralgias, and blood markers of inflammation such as leukocytosis or elevated erythrocyte sedimentation rate.
  • Extracutaneous manifestations of Sweet’s syndrome may occur.
  • Sweet’s syndrome may be idiopathic or seen in association with other systemic illnesses, most commonly malignancy (especially hematologic), connective tissue disease, inflammatory diseases, infection, pregnancy, or triggered by medications or pathergy (injury).
  • Sweet’s syndrome is almost universally responsive to treatment with systemic corticosteroids; however, given the chronic intermittent nature of the disease, it may require alternative immunosuppression with steroid-sparing agents. Anti-neutrophilic agents often are effective in the management of Sweet’s syndrome.

Introduction

Indurated, often painful, erythematous nodules are the characteristic skin lesion that marks Sweet’s syndrome. Skin lesions may be bullous or pseudocellulitic in appearance. Skin lesions of Sweet’s syndrome are often accompanied by signs of systemic inflammation: fever, malaise, arthralgias, and blood markers of inflammation such as leukocytosis or elevated erythrocyte sedimentation rate. Extracutaneous manifestations of Sweet’s syndrome may occur.

The diagnostic criteria for Sweet’s syndrome have been proposed in the literature, though remain somewhat nonspecific. To meet diagnostic criteria, a patient must have both of the major criteria and meet two of the five minor criteria:

Major criteria:

  1. Abrupt onset of tender or painful erythematous or violaceous plaques or nodules
  2. Predominantly neutrophilic infiltration in the dermis without leukocytoclastic vasculitis

Minor criteria:

  1. Preceding fever or infection
  2. Accompanying fever, arthralgia, conjunctivitis, or underlying malignant lesion
  3. Leukocytosis
  4. Good response to systemically administered corticosteroids and not to antibiotics
  5. Increased erythrocyte sedimentation rate

Common laboratory findings seen in association with Sweet’s syndrome include leukocytosis, elevated erythrocyte sedimentation rate, and there are rare reports of p-ANCA antibodies.

Sweet’s syndrome may be idiopathic (estimated 70% of cases) or seen in association with other systemic illnesses. Common associated diseases include:

  • malignancy
  • systemic inflammatory disease
  • medication-triggered Sweet’s
  • infection
  • pregnancy
  • pathergy

The relationship between Sweet’s syndrome and its associated conditions is complex. Flares of Sweet’s syndrome do not always occur in concordance with flares of the underlying disease.

Sweet’s syndrome is almost universally responsive to treatment with systemic corticosteroids; however, given the chronic intermittent nature of the disease, it may require alternative immunosuppression with steroid-sparing agents. Anti-neutrophilic agents often are effective in the management of Sweet’s syndrome.