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Skin-nontumor / Clinical Dermatology

Other dermatoses

Sweet’s Syndrome

Reviewer: Mowafak Hamodat, MB.CH.B, MSc., FRCPC, Eastern Health, St. Johns, Canada (see Reviewers page)
Revised: 2 August 2011, last major update August 2011
Copyright: (c) 2002-2011, PathologyOutlines.com, Inc.


● Also called acute febrile neutrophilic dermatosis
● Abrupt onset of tender or painful erythematous plaques and nodules on the face and extremities and less commonly on the trunk, in association with fever (usually), malaise and a neutrophil leukocytosis
● Associated with AML, less often with solid malignancies
● Often females, any age but rare in childhood
● Unknown etiology, but may represent immunological hypersensitivity reaction


● Most cases respond to oral corticosteroids
● Thalidomide was successful in one patient who failed to respond to metronidazole, dapsone and methotrexate; IV immunoglobulin was used in a child with concurrent immunodeficiency
● Also response to 5-azacytidine in patient with myelodysplastic syndrome
● A case of histiocytoid Sweet's syndrome was responsive to dapsone; dapsone has also been used with systemic corticosteroids in a patient who was HIV positive

Micro description

● Intense neutrophilic dermal infiltrate in reticular dermis, may be perivascular, diffuse and surround sweat glands; edema with marked leukocytoclasia; marked papillary edema
● Occasional presence of dermal papillary microabscesses can result in confusion with dermatitis herpetiformis
● Epidermis is normal, occasionally slight spongiosis, vesiculation with spongioform pustule
● Necrotic keratinocytes may be present
● Variable eosinophils, lymphocytes and histiocytes
● Blood vessels are dilated and show endothelial swelling

Micro images

Contributed by Angel Fernandez-Flores, MD, PhD, Hospital El Bierzo and Clinica Ponferrada, Spain:

Differential diagnosis

● Rheumatoid neutrophilic dermatitis, neutrophil-rich variant of anaplastic large cell lymphoma
● The presence of fibrinoid vascular changes distinguishes necrotizing vasculitis such as leukocytoclastic vasculitis, erythema elevatum diutinum, and granuloma faciale from Sweet’s Syndrome
● Granuloma fasciale: fibrinoid necrosis is minimal but eosinophils are prominent
● Late lesions of erythema elavatum diutinum and granuloma faciale show fibrosis, not seen in Sweet’s Syndrome
● Pyoderma gangrenosum: has ulcer, no leukorrhexis
● Gram stain and PAS exclude infection
● Behcet disease may be associated with lesions similar to Sweet’s syndrome

Additional references

Dermatol Online J 1999;5:8, DermNetNZ

End of Skin-nontumor / Clinical Dermatology > Other dermatoses > Sweet’s Syndrome

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