Sweet described the syndrome of acute febrile neutrophilic dermatosis in 1964. The cause is unknown but may be associated with a variety of conditions including drug exposure. It can be diagnosed using specific criteria.


Major Criteria:

(1) abrupt onset of painful, erythematous plaques and nodules

(2) histopathologic evidence of a dense neutrophilic infiltrate in the dermis without evidence of leukocytoclastic vasculitis


Features of Classic Sweet's Syndrome:

(3) pyrexia > 38°C

(4) associated condition

(4a) an underlying hematologic or visceral malignancy

(4b) an inflammatory disease

(4c) pregnancy

(4d) following an upper respiratory or gastrointestinal infection

(4e) following a vaccination

(5) excellent response to treatment with systemic glucocorticoids or potassium iodide

(6) abnormal laboratory tests at presentation, with 3 or more of the following:

(6a) ESR > 20 mm/h

(6b) increased C-reactive protein

(6c) WBC count > 8,000 per µL

(6d) neutrophils in differential > 70%


Features of drug-induced Sweet's syndrome:

(7) pyrexia > 38°C

(8) drug associated

(8a) temporal relationship between drug ingestion and clinical presentation

(8b) recurrence after oral rechallenge

(9) temporally-related resolution of lesions after drug withdrawal



• diagnosis of classic Sweet's syndrome: 1 + 2 + (2 or more from 3, 4, 5, 6)

• diagnosis of drug-induced Sweet's syndrome: 1 + 2 + 7 + 8 + 9


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