Febrile neutrophilic dermatosis

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at April 26, 2016
StartDiseasesFebrile neutrophilic dermatosis

Febrile neutrophilic dermatosis is a very rare skin disease that results in lesions and other physical symptoms. It is also called Sweet's syndrome after Dr. Robert Douglas Sweet, who first described the syndrome in 1964.


Definition & Facts

Originally, this condition was called acute febrile neutrophilic dermatosis because doctors believed that all patients had a fever and skin plaques with dense clusters of neutrophil, a type of white blood cell. However, as more patients were diagnosed with febrile neutrophilic dermatosis, it was realized that not all patients had a fever or the neutrophilic skin plaques. Therefore, this skin condition is more commonly called Sweet's syndrome in recent times. This condition affects 3 out of 10,000 people globally.

Symptoms & Complaints

The first sign of febrile neutrophilic dermatosis is often a fever, but this only happens in about 50 percent of patients. Next, tiny red bumps begin to appear along the patient's body. They most typically appear on the fingers, hands, and arms, but they can also occur along the trunk, neck, inside of the mouth, or head.

In many patients, the lesions have a dense amount of white blood cells within them. These skin lesions quickly grow in size and spread in location, and they are typically very painful. The lesions can look like small bumps, blisters, large flat patches, large lumps, ring shaped lesions, or ulcers. The lesions can also appear on the eye, resulting in conjunctivitis, glaucoma, or other problematic eye conditions.

In very rare circumstances, a person may develop subcutaneous febrile neutrophilic dermatosis, which happens when the painful lesions erupt below the skin, where they cannot be seen. People with Sweet's Syndrome can have just one type of the lesion, or they can have multiple different types at the same time. The skin lesions can be accompanied by fatigue, headaches, painful joints, and a moderate to high fever.


Febrile neutrophilic dermatosis is usually triggered by an underlying condition. One of the most common causes is leukemia, but other cancers or tumors can also result in an outbreak of Sweet's syndrome. Autoimmune diseases like rheumatoid arthritis and inflammatory bowel disease can also trigger febrile neutrophilic dermatosis.

Other health conditions that can cause febrile neutrophilic dermatosis include pregnancy, streptococcal infections, chest infections, and even sunburn. People with Sweet's syndrome can develop the skin condition up to 6 years after being diagnosed with one of the triggering health conditions. Though doctors do not know why some people with these conditions develop Sweet's syndrome, they theorize that it may be due to genetic factors or environmental factors.

Febrile neutrophilic dermatosis may also be a reaction to certain medications that raise white blood cell counts. Drugs that can cause Sweet's syndrome include azathioprine, cotrimoxazole, carbamazepine, nonsteroidal anti-inflammatory drugs, and granulocyte colony-stimulating factors. In some cases, there is no discovered cause for febrile neutrophilic dermatosis but a link appears between the tumor necrosis factor alpha and proinflammatory cytokines interleukin-1 levels in the body.

Diagnosis & Tests

The main criteria used to diagnose febrile neutrophilic dermatosis is the sudden appearance of reddish purple plaques or lesions that feel tender and painful. A complete medical history will also be required to diagnose Sweet's syndrome, since it is more common after a fever or other health condition. If a doctor suspects that a patient has febrile neutrophilic dermatosis, a biopsy is often ordered to confirm the diagnose.

When a sample of a lesion is examined in a lab, it normally has certain characteristics. Often, a sample from a patient with Sweet's syndrome will mostly be composed of neutrophils, and no inflammation of the blood vessels will occur with this increase in white blood cells. However, in rare cases, a lesion can only contain moderately high amounts of neutrophils, and in severe cases, the blood vessels of a patient may be inflamed. Therefore, there are other blood tests that can be used to diagnose a patient if the biopsy is not conclusive.

People with febrile neutrophilic dermatosis tend to have raised levels of C-reactive proteins, white blood cells, and anti-neutrophil cytoplasmic antibodies in their blood. If the symptoms do not respond to typical febrile neutrophilic dermatosis treatments, a doctor may run more tests or reconsider the diagnosis.

Treatment & Therapy

Sweet's syndrome gradually goes away without treatment, but medications can make the painful lesions clear up within just three days. The most common treatments for people with febrile neutrophilic dermatosis is corticosteroids. These medications can be applied as an oral pill, an injection, or an ointment. After the lesions clear up, patients on corticosteroids should gradually taper usage down over the next few weeks.

Low dosages may be given to patients for several months to prevent a re-occurrence from happening. For patients who have a bad reaction to corticosteroids or do not respond to corticosteroids, Sweet's syndrome may be treated with other medications that encourage neutrophils to migrate and dissolve.

Other medicines used to treat febrile neutrophilic dermatosis include dapsone, colchicine, potassium iodide, indomethacin, prednisone, cyclosporine, or doxycycline. While dealing with the lesions, it is necessary for patients to avoid picking at the lesions, and doctors may prescribe certain painkillers that can help to ease the discomfort caused by the lesions.

Prevention & Prophylaxis

If a person has already had febrile neutrophilic dermatosis, they can continue to take low dosages of medication to avoid having a recurrence and experiencing another outbreak of the lesions. Avoiding excessive exposure to sunlight is another beneficial way of keeping it from recurrence.