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Sweet Syndrome: Symptoms, Causes, Diagnosis, and Treatment of Acute Febrile Neutrophilic Dermatosis

Oghenefejiro Okifo | MD

Medically reviewed by Oghenefejiro Okifo | MD, Harvard Medical School | Henry Ford Hospital - Detroit, MI on June 2nd, 2023.

Key Takeaways

  • Acute febrile neutrophilic dermatosis typically affects women aged 30-60 and presents with tender, red-purple papules or plaques that appear suddenly on the face, neck, and upper extremities.

  • Approximately 85% of patients develop fever above 100.4°F (38°C) within days of skin lesion onset, often accompanied by neutrophil counts exceeding 8,000 cells/μL.

  • Up to 50% of cases are associated with hematologic malignancies (especially acute myeloid leukemia), inflammatory bowel disease, or recent upper respiratory infections.

  • Oral prednisone at 1mg/kg daily typically resolves lesions within 2-4 weeks, though 30% of patients experience recurrence within months if underlying conditions persist.

  • Diagnostic criteria require painful skin lesions, fever, neutrophilia, and dramatic response to corticosteroids—skin biopsy shows dense neutrophilic infiltrate without infection.

Sweet syndrome, also known as acute febrile neutrophilic dermatosis, is a rare skin condition that causes a sudden outbreak of painful red or purple bumps on the skin. It usually occurs along with a fever and can affect people of any age, but is most common in middle-aged women. Sweet syndrome is not contagious.

Symptoms of Sweet Syndrome

The main symptoms of Sweet syndrome are:

  • Fever

  • Painful red or purple bumps that appear suddenly on the arms, legs, face, neck, or other parts of the body

  • Bumps that grow quickly and join together to form large patches

  • Blisters or pimple-like bumps that may break open and become infected

Other symptoms may include feeling like you have the flu, fatigue, headaches, joint pain, mouth sores, and pink eye.

Sweet Syndrome: Symptoms, Causes, Diagnosis, and Treatment of Acute Febrile Neutrophilic Dermatosis

Causes of Sweet Syndrome

In many cases, the exact cause of Sweet syndrome is unknown. However, it can be triggered by an underlying health problem such as:

  • Blood cancers like leukemia or lymphoma

  • Inflammatory bowel diseases like ulcerative colitis or Crohn's disease

  • Infections like strep throat or a chest infection

  • Solid tumor cancers like breast or colon cancer

  • Pregnancy

  • Rheumatoid arthritis

  • Certain medications, especially granulocyte-colony stimulating factor used to treat low white blood cell counts in cancer patients

Diagnosing Sweet Syndrome

To diagnose Sweet syndrome, your doctor will examine your skin rash and may order tests such as:

  • A skin biopsy to examine a small sample of the rash under a microscope

  • Blood tests to look for high levels of white blood cells called neutrophils or signs of a blood disorder

  • Imaging tests like X-rays or CT scans to look for an underlying cause

Treating Sweet Syndrome

Sweet syndrome may go away on its own, but this can take weeks or months. Treatment options include:

  • Corticosteroid pills to reduce inflammation, redness, itching and swelling

  • Corticosteroid creams or gels applied to the skin, especially for smaller bumps

  • Corticosteroid injections into painful or swollen bumps

  • Treating the underlying cause, such as cancer, infection, or stopping a triggering medication

With treatment, the skin rash usually heals without scarring, although skin color changes may persist for several months. Sweet syndrome can recur, especially if it was caused by cancer. If you notice symptoms returning, see your doctor promptly.

To learn more about this rare skin condition, visit the National Organization for Rare Disorders, American Osteopathic College of Dermatology, or DermNet NZ.

The Bottom Line

This inflammatory condition requires immediate corticosteroid treatment to prevent complications and typically resolves completely without scarring when caught early. However, thorough evaluation for underlying malignancy or autoimmune disease is essential since half of all cases signal serious systemic conditions. If you're experiencing sudden painful skin bumps with fever, Doctronic can help you get rapid evaluation and appropriate treatment.

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