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Synonyms: Sweet's syndrome
The disease is characterised by sudden appearance of red tender plaques on the skin, usually on the limbs or neck but sometimes elsewhere. It was first described in 1964 by the dermatologist, Dr Robert Sweet (1917-2001), from Plymouth.
It usually occurs in middle-aged women, but men, children and the elderly may also be affected. It is very uncommon. There were six case reports in world literature in 2008-2009. Women exceed men by 2 or 3:1 except in association with malignancy when it is equal. Women are typically 30 to 50 years old but men are typically 50 and older. In the limited number of cases seen in children, there is often disease of the immune system.
It appears to be a reaction to a number of possible triggering stimuli. They include:
- Upper respiratory tract infection, including bronchitis and streptococcal sore throat
- Inflammatory bowel disease
- Rheumatoid arthritis and other inflammatory diseases
- Haematological malignancy, most often acute myelogenous leukaemia or myelodysplasia
- Malignancy of bowel, genitourinary tract or breast
- It may occur at the site of trauma in areas exposed to the sun
- A number of drugs have been implicated, including granulocyte colony-stimulating factor (GCSF), and non-steroidal anti-inflammatory drugs (NSAIDs)
- In many cases no cause is found
The patient is usually systemically unwell:
- Moderate to high fever that may occur with the skin lesions or precede them by days or even weeks.
- General malaise.
- One or more tender red papules or plaques. They enlarge and persist for several weeks. They may have blisters, pustules or ulcers. Sometimes they appear to clear in the centre.
- Arthralgia and headache.
- Conjunctivitis and episcleritis.
- Ulcers on lips, buccal mucosa and tongue.
- Sometimes other organs are affected including bones, nervous system, kidneys, intestines, liver, heart, lungs, muscles and spleen.
- There may be pulmonary infiltration causing cough and a shadow on CXR, and lesions in the central nervous system (CNS) may cause convulsions. These lesions are rare. It has been suggested that the CNS disease is a separate entity.
There is a variant called "neutrophilic dermatosis of the dorsal hand", in which bluish or grey nodules like abscesses appear on the dorsum of the hands. These nodules may ulcerate. This is sometimes known as "pustular vasculitis" of the hands, because biopsy shows vasculitis with an infiltration of neutrophil white cells.
- White cell count is elevated with a neutrophil leucocytosis.
- Erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP) is raised.
- Biopsy if often required for confirmation. Numerous neutrophil inflammatory cells are seen with fragmented neutrophils, called leucocytoclasia, and swelling of the endothelial lining of blood vessels.
- Abrupt onset of tender or painful erythematous plaques or nodules, occasionally with vesicles, pustules, or bullae.
- Predominantly neutrophilic infiltration in the dermis without leucocytoclastic vasculitis.
- Preceding nonspecific respiratory or gastrointestinal tract infection or vaccination or associated with inflammatory disease, haemoproliferative disorders, solid malignant tumours, or pregnancy.
- Periods of general malaise and fever with body temperature above 38°C.
- Laboratory values during onset showing ESR greater than 20, positive CRP, segmented nuclear neutrophils, bands exceeding 70% in peripheral blood smears, and leucocytosis exceeding 8000/μL. At least three of these four values are necessary.
- Excellent response to treatment with systemic corticosteroids or potassium iodide.
Response to treatment is usually very swift, although it will resolve without treatment:
- Prednisolone is given at a dose of 1 mg/kg/day and, within a few days, the fever, skin lesions and other symptoms resolve.
- High-potency topical steroids, eg clobetasol propionate 0.05%, or intralesional glucocorticoids may also be useful in localised lesions.
- For long-term management many drugs are helpful. Many of the medications work by inhibiting neutrophil chemotaxis, but none has been shown to be better than corticosteroids. Examples include indometacin, colchicine, potassium iodide, dapsone, ciclosporin, doxycycline, metronidazole, isotretinoin, methotrexate, cyclophosphamide, chlorambucil, adalimumab, infliximab, intravenous immunoglobulin (IVIG), pulse doses of methylprednisolone and interferon alfa.[5, 6]
The lesion may be the first indication of an underlying malignancy and, if the disease is severe, this should be considered seriously. Cases associated with malignancy are often bullous or ulcerative and resemble atypical PG. These lesions are often resistant to treatment and are recurrent. About 15 to 20% of cases are associated with malignancy.
With or without treatment there is usually complete resolution without any residual scar. There is usually a single episode but, in about a third of cases, it is recurrent. These tend to be associated with malignancy.
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Further reading & references
- Derm Net NZ.; Sweet's disease. Excellent pictures.
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