Sweet Syndrome

Sweet syndrome, also known as acute febrile neutrophilic dermatosis, is a rare inflammatory skin condition. It causes a sudden fever and a painful rash. The rash most often appears on your upper body. Like on your arms, face, trunk or neck. But the rash can form on any skin area.

This condition can happen with certain medications, infections, pregnancy and cancer. It’s best to talk to a healthcare provider if you notice symptoms. Treatment options are available to reduce symptoms and discomfort.

Sweet syndrome symptoms

The symptoms of Sweet syndrome come on suddenly. On your skin, you might notice a rash with the following features:

• Bumpy or blistering (filled with fluid or pus)
• Discolored (darker than your natural skin tone or red to purple)
• Lumpy and deep under your skin (feels like a bruise)
• Painful to the touch
• Breaks open (a wound or ulcer)

You may also have:

• A fever higher than 100.4 degrees Fahrenheit (38 degrees Celsius)
• Eye problems (blurred vision, pain)
• Fatigue
• Headaches
• Joint pain and muscle aches

Sweet syndrome causes

Healthcare providers don’t know exactly why Sweet syndrome develops. Research suggests it may happen when your immune system becomes overactive. Too many white blood cells (neutrophils) move into your skin, causing painful bumps and swelling.

Researchers are also studying whether genes or chromosomal changes play a role in some cases.

Although the exact cause isn’t known, certain factors can trigger or be associated with Sweet syndrome. These are grouped into three main types:

• Classical (idiopathic) Sweet syndrome: The specific cause is unknown, but it may appear after infections (like an upper respiratory or gastrointestinal infection) or during pregnancy.
• Malignancy-associated Sweet syndrome: This links to an underlying cancer, most often a blood cancer like acute myeloid leukemia.
• Drug-associated Sweet syndrome: Symptoms triggered by certain medications, like antibiotics (co-trimoxazole), nonsteroidal anti-inflammatory drugs (NSAIDs) or granulocyte colony-stimulating factor (G-CSF).

Risk factors

Anyone can develop Sweet syndrome, but it’s most common in:

• Females
• Adults between ages 30 and 60

Complications of Sweet syndrome

This condition may cause inflammation in areas of your body other than your skin. While rare and more common in the malignancy type, it could affect your:

• Bones (sterile osteomyelitis)
• Brain or nerves (aseptic meningitis)
• Eye (episcleritis, scleritis, keratitis, etc.)
• Heart (myocarditis)
• Lungs (alveolitis or pleural effusion)

How doctors diagnose Sweet syndrome

A healthcare provider can diagnose this condition with a physical exam and tests. They’ll look closely at your skin to understand your symptoms. To confirm the diagnosis, they may do a blood test and a skin biopsy. During the biopsy, your provider removes a small piece of skin from the affected area and sends it to a lab for testing.

Sweet syndrome diagnostic criteria

To make a diagnosis, your provider will look for two main signs. Both of these must be present:

1. A sudden outbreak of painful, discolored bumps or raised patches (plaques or nodules) on your skin.
2. A skin biopsy that shows a buildup of a specific type of white blood cell (neutrophils) in your skin without signs of blood vessel inflammation (vasculitis).

After they find these two major signs, your provider will also look for at least two of the following features to confirm the diagnosis:

• Fever higher than 100.4 F (38 C)
• Illness started after an infection (like a cold or stomach infection) or is linked to another condition (like an inflammatory disease, cancer or pregnancy)
• Blood tests show a high number of white blood cells (neutrophils) and elevated inflammation markers
• Skin rash improves quickly with a corticosteroid treatment (like prednisone)

Sweet syndrome treatment

The main treatment for Sweet syndrome is a corticosteroid medication, like prednisone. You can take this medication by mouth with a glass of water. It also comes in other forms, like an injection or a topical cream that you apply to your skin. It helps reduce inflammation and calms an overactive immune system.

Steroids work by lowering the number of white blood cells and other immune responses that can damage tissue. This treatment is usually short term.

If an underlying condition (like cancer) is causing Sweet syndrome, your provider will treat that condition. If a medication triggered symptoms, stopping it may help — but only do this under your provider’s guidance.

If symptoms return after treatment, your provider may recommend other medications, like:

• Chlorambucil
• Colchicine
• Cyclosporine
• Dapsone
• Doxycycline
• Indomethacin
• Isotretinoin
• Methotrexate
• Potassium iodide

Sometimes, Sweet syndrome goes away on its own without medical treatment.

When should I see my healthcare provider?

Contact your provider if you have symptoms that don’t go away, are getting worse or return after treatment. Sometimes, the spots from this condition can break open and cause an infection. If you notice painful swelling, oozing or a sore that isn’t healing, and you have a fever, let your provider know right away.

What questions should I ask my provider?

If you have this condition, you might want to ask your healthcare provider:

• What caused this condition?
• What treatment options are available and what are the side effects?
• How long will it take for my symptoms to improve with treatment?
• Will I have scars after treatment?
• What’s the risk of Sweet syndrome coming back in the future?

What can I expect if I have Sweet syndrome?

Sweet syndrome has a good outlook. With proper treatment, your skin may heal without scarring. You might notice some temporary skin discoloration. But this often fades over time.

When symptoms are active, the spots can be uncomfortable. They may last for days, weeks or even months, depending on the cause. The good news is that symptoms usually respond well to steroid treatment.

Sometimes, Sweet syndrome can come back (recur). Your healthcare provider can help you identify and manage triggers to help reduce the chance of future flare-ups.