Acute Febrile Neutrophilic Dermatosis (Sweet Syndrome) Clinical Presentation

Updated: Jun 02, 2020
  • Author: Yoon-Soo (Cindy) Bae, MD; Chief Editor: William D James, MD  more...
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Typically, fever precedes the appearance of lesions in Sweet syndrome (acute febrile neutrophilic dermatosis) by several days to weeks; however, fever and lesions of may also occur simultaneously. [2] Many patients report an upper respiratory tract infection, tonsillitis, or flulike syndrome 1-3 weeks prior to onset of skin lesions. [2, 81] Recent vaccination or a gastrointestinal tract infection may also precede the eruption. [44, 82]

The crop of plaques or nodules in the classic form often appears abruptly and may persist for days to several months if untreated. [2, 82]


Physical Examination

Cutaneous manifestations of Sweet syndrome

Typical skin lesions are bright-red, reddish-blue, or violet papules, plaques, or nodules. Massive subepidermal edema can produce a deceptively vesicular appearance, with pustules sometimes studding these lesions. Papules often coalesce into circinate or arcuate plaques. [2, 16, 81, 82] Plaques can cause pain and burning, but they are not pruritic. Lesions spontaneously resolve without scarring. [2]

The face, neck, and extremities primarily are affected, characteristically in an asymmetric distribution. [2] However, several reports note atypical distribution of Sweet syndrome (acute febrile neutrophilic dermatosis) lesions. One report describes lesions in the external auditory canal and tympanic membrane. [83] Facial or giant cellulitis–like, [84] necrotizing fasciitis type, subcutaneous types, and photo-distributed violaceous plaques with heliotrope rash, malar erythema, scalp involvement, and Gottron-like papules [85] are other clinical subtypes reported. [86]

Ulcers and bullae are more common in malignancy-associated disease than in other forms. These lesions may be extensive and generally are hard to treat. [82]

See the images below.

Multiple lesions on the scalp. Courtesy of Alexa F Multiple lesions on the scalp. Courtesy of Alexa F Boer Kimball, MD, MPH.
Close-up of a scalp lesion. Courtesy of Alexa F Bo Close-up of a scalp lesion. Courtesy of Alexa F Boer Kimball, MD, MPH.

Sweet syndrome of the hands

Sweet syndrome on the dorsum of the hand is not uncommon. The lesions are predominantly distributed over the dorsal aspects of the fingers and hands in a roughly symmetrical pattern, with possible involvement of other extensor surfaces. [81]

Sweet syndrome of the oral and ocular mucosae

Sweet syndrome can also manifest in the oral cavity or eyes. The condition is known to manifest as oral lesions on the lips, buccal mucosa, and/or tongue; these lesions most commonly appear in context of a hematologic disorder. [10] Conjunctivitis and episcleritis are the most common ocular forms. Other reported ocular manifestations include uveitis, limbal nodules, glaucoma, subconjunctival hemorrhage, scleritis, iritis, and sudden visual loss. [87, 88, 89]

Extracutaneous manifestations of Sweet syndrome

Sweet syndrome can involve extracutaneous organ systems. [2] Pulmonary involvement may manifest as dyspnea, chronic cough, or pulmonary infiltrates or effusions on chest radiographs. In rare cases, symptoms may become severe enough to cause respiratory failure or bronchiolitis obliterans organizing pneumonia. Fortunately, most of these cases are highly responsive to glucocorticoid therapy. [39, 90, 91, 92]

Renal involvement can be demonstrated by the presence of proteinuria, hematuria, and decreased creatinine clearance. [2] See the Creatinine Clearance (measured) calculator.

Other sites that have been reported include the bones, intestines, joints, bone marrow, liver, heart, muscles, and spleen. [2, 13, 32, 45, 93, 94, 95, 96, 97, 98]

A few cases of systemic inflammatory response syndrome (SIRS) progressing to shock and organ dysfunction have been reported, with rapid improvement using high-dose intravenous methylprednisolone. The treatment efficacy highlights the association of SIRS with Sweet syndrome, which can be hard to distinguish from infection. [99, 100, 101]

Among children, cases of acquired cutis laxa have been reported in lesions consistent with Sweet syndrome. [102] A 2-year-old girl diagnosed with both Sweet syndrome and cutis laxa was found to have acute necrosis in the cardiac apex and interventricular septum and focal chronic inflammatory and granulation tissue in the aortic wall. The authors suggest that children with both Sweet syndrome and cutis laxa undergo complete cardiac evaluation by a pediatric cardiologist, as these findings can indicate a potentially fatal condition. [103]

CNS involvement has been reported in 69 cases in the literature since 1986. [104] Encephalitis and meningitis are common neurologic manifestations in these cases. [23] The most common symptoms reported are headaches, altered consciousness, and seizures. [23] There may be a genetic link, as reports have shown an association between HLA-B54 and HLA-CW1 and CNS-related Sweet syndrome in a population of Japanese patients. [23] CNS Sweet syndrome can be differentiated from Behçet syndrome, as the latter features more progressive and severe CNS involvement, whereas Sweet syndrome transiently involves the CNS, although recurrences may occur. [23] Of note, there can be a delay of up to 10 years from the onset of neurological symptoms to the onset of the characteristic skin lesions. [25]

In addition to CNS involvement, peripheral neuropathy has also been reported. [23] Cerebrospinal fluid pleocytosis also has been described, as has sterile chronic recurrent multifocal osteomyelitis in children. [105]

Ocular involvement has also been reported, characterized by conjunctivitis, scleritis, iritis, choroiditis, and retinal vasculitis; ocular involvement can be sight-threatening. [106]


Like pyoderma gangrenosum, Sweet syndrome is known to cause pathergy in which lesions occur in areas of minor trauma, such as sites of scratches, bites, and venipuncture. [35] The lesions may also be photodistributed or localized to the site of a previous phototoxic reaction (eg, sunburn). [2, 35]

Underlying disease

It is important to recognize and treat any associated or underlying systemic diseases or malignancies. Sweet syndrome may be a clue to the diagnosis of a systemic disorder or malignancy. [107] Imaging studies, such as ultrasonography, CT scanning, positron-emission tomography (PET) scanning, or MRI, may be helpful in identifying such underlying malignancies.


Sweet syndrome can occur during pregnancy and may recur in subsequent pregnancies. Presently, it is believed that the disease is not associated with fetal harm. [4]

Diagnostic criteria

Classic or idiopathic Sweet syndrome

Classic or idiopathic Sweet syndrome, as proposed by Su and Liu [108] and revised by von den Driesch, [28] depends on the presence of both major criteria and at least two minor criteria.

Major criteria are as follows:

  • Abrupt onset of tender or painful erythematous plaques or nodules, occasionally with vesicles, pustules, or bullae
  • Predominantly neutrophilic infiltration in the dermis without leukocytoclastic vasculitis per microscopic examination of a biopsy sample

Minor criteria are as follows:

  • Association with an underlying disorder, including the following: (1) respiratory tract infection, (2) gastrointestinal tract infection, (3) vaccination, (4) inflammatory disease, (5) hematoproliferative disorders, (6) solid malignant tumors, (7) pregnancy
  • Pyrexia (temperature >38°C)
  • Abnormalities in at least three of the following four laboratory tests during onset: (1) elevated erythrocyte sedimentation rate (ESR) (>20 mm), (2) positive C-reactive protein (CRP) result, (3) peripheral blood smear showing segmented nuclear neutrophils, bands >70%, (4) leukocytosis (count >8000/µL)
  • Excellent response to treatment with systemic corticosteroids or potassium iodide

Drug-induced Sweet syndrome

Drug-induced Sweet syndrome (proposed by Walker and Cohen [14] ) is diagnosed if all five of the following criteria are met:

  • Abrupt onset of painful erythematous plaques or nodules
  • Histopathologic evidence of a dense neutrophilic infiltrate without evidence of leukocytoclastic vasculitis
  • Pyrexia (temperature >38°C [100.4°F])
  • Temporal relationship between drug ingestion and clinical presentation, or temporally related recurrence after oral challenge
  • Temporally related resolution of lesions after drug withdrawal or treatment with systemic corticosteroids


Generally, lesions resolve without scarring, although pigmentary changes may take months to fade.