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Sweet's Syndrome

Sweet’s syndrome (also known as acute febrile neutrophilic dermatosis) is a rare skin disorder characterised by a fever and the appearance of tender red or purple lumps or patches on the skin that may ulcerate. Its main signs include fever and painful skin lesions that appear mostly on arms, neck, head and trunk. It is not contagious, not hereditary and not a form of skin cancer.

The diagnosis of Sweet's syndrome is made based on a combination of clinical symptoms and characteristic physical and pathologic features. Sweet's syndrome was first described by Robert Sweet in 1964.

The exact cause of Sweet's syndrome isn't known. In some people, it can be triggered by an infection, illness or certain medications. Sweet's syndrome can also occur with some types of cancer. It is much more common in females between 30-60 years old, although it can also occur in males and in other age groups. It can occur in people of any ethnicity and skin type. In about half of all cases, it manifests following an upper respiratory tract or gastrointestinal infection or a drug reaction from medications such as non-steroidal anti-inflammatory medications. In some patients, it can be a manifestation of another condition such as inflammatory bowel disease, lupus erythematosus or rheumatoid arthritis. In a few cases, it is a result of hormonal changes such as in pregnancy or thyroid gland disorders and more rarely may be a sign of cancer such as blood, breast or bowel cancer.

Some women develop Sweet's syndrome during pregnancy. Sweet's syndrome may result from a sensitivity to medication. Drugs linked to Sweet's syndrome include azathioprine (Azasan, Imuran), granulocyte colony stimulating factor, certain antibiotics and some nonsteroidal anti-inflammatory drugs.

There is also Neuro-Sweet's disease (NSD), which is a rare variant of Sweet's syndrome.

Symptoms

Sweet’s syndrome may cause some or all of the following symptoms. These may arise together or over a period of hours/days:

  • skin rash

  • tiredness, lack of energy and feeling unwell

  • high fever

  • aching joints and muscles

  • mouth ulcers

  • sore red eyes

 

Diagnosis

This is the revised Sweet's syndrome diagnostic criteria. Findings in patients must fulfil both of the major criteria and at least two of the minor criteria to allow a diagnosis of Sweet's syndrome:

 

Major Criteria

  • Abrupt onset of painful erythematous plaques or nodules

  • Predominantly neutrophilic infiltration in the dermis without evidence of leukocytoclastic vasculitis

 

Minor Criteria

  • Preceded by a nonspecific respiratory or gastrointestinal tract infection or vaccination OR associated with an underlying hematologic or visceral malignancy, inflammatory disease, or pregnancy

  • Temperature >38oC

  • Laboratory values during onset: ESR >20 mm/hr, positive C-reactive protein, segmented-nuclear neutrophils and bands >70% in peripheral blood smear, leukocytes >8000/microliter (three out of four of these values are necessary)

  • Excellent response to treatment with systemic steroids (anti-inflammatory glucocorticoids or steroids) or potassium iodide

 

Lab tests required to confirm the diagnosis:

  • Skin biopsy is one of the major criteria for diagnosis, all patients have a neutrophilic infiltrate on skin histology.

  • Blood tests such as high levels of a type of white blood cells called neutrophils, can help to make a diagnosis of Sweet’s syndrome. CBC with differential: Greater than 95% of patients have leukocytosis (>8 x 109/L) and anemia (Hg < 12 g/dL). In almost half of the patients there is neutrophilia (>70% neutrophils) and thrombocytosis (Plt > 400,000/mm3).

  • Inflammatory markers: Over 95% of patients have an elevated erythrocyte sedimentation rate (ESR) (> 20 mm/hour).

  • Pregnancy test: Pregnancy testing should be performed in all menstruating females to help diagnose or rule out pregnancy-induced Sweet syndrome.

 

Treatment

Systemic corticosteroids are the first-line therapy for the majority of patients, including patients with known underlying malignancy. Because systemic corticosteroid treatment can cause significant rise in peripheral blood neutrophil counts, laboratory studies should be performed prior to starting therapy. There is no standard dosing regimen, although a commonly used dose is 2 mg/kg/day followed by a tapering dose. Tapering needs to be slow as the disease can flare with lower doses of systemic corticosteroids.

If steroids don't work, other immunosuppressant drugs such as cyclosporine, dapsone, or indomethacin may be prescribed. Alternatives to corticosteroids are:

  • Dapsone

  • Potassium iodide

  • Colchicine (Colcrys, Mitigare)

 

Topical treatments: Strong steroid creams or ointments may help, especially with smaller lumps, and may help reduce the tenderness.

References:

- J Dtsch Dermatol Ges. 2017 Nov;15(11):1081-1088. doi: 10.1111/ddg.13350. Epub 2017 Oct 5. https://www.ncbi.nlm.nih.gov/pubmed/28981179

- British Association of Dermatologists, Sweet’s Syndrome

http://www.bad.org.uk/shared/get-file.ashx?id=182&itemtype=document

- Mayo Clinic, Sweet’s Syndrome

https://www.mayoclinic.org/diseases-conditions/sweets-syndrome/symptoms-causes/syc-20351117