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Acute febrile neutrophilic dermatosis in Infant/Neonate
See also in: Cellulitis DDx
Other Resources UpToDate PubMed

Acute febrile neutrophilic dermatosis in Infant/Neonate

See also in: Cellulitis DDx
Contributors: Erin X. Wei MD, Tyler Werbel MD, Andrew Walls MD, Belinda Tan MD, PhD, Susan Burgin MD
Other Resources UpToDate PubMed


Acute febrile neutrophilic dermatosis, also known as Sweet syndrome, is an inflammatory disorder manifesting as multiple sterile, typically painful, edematous, erythematous plaques that are usually associated with fever and leukocytosis. The disease is typically limited to the skin, although any organ system may be affected. It is only rarely reported in children and infants, accounting for about 5% of all cases. In the pediatric population, the mean age of onset is 5 years, and there is a male predominance, particularly for children younger than 3 years. Sweet syndrome is classified by etiology:
  • Classic idiopathic
  • Pregnancy-associated
  • Parainflammatory
  • Paraneoplastic
  • Drug-associated
A recent classification contracts this as follows:
  • Classic (includes all inflammatory causes including infection, inflammatory bowel disease [IBD], and pregnancy)
  • Paraneoplastic and drug-related
Pediatric Sweet syndrome is usually "classic" (total approximately 75%, with around 40% idiopathic and a third parainflammatory). About 25% are associated with malignancies. The predominant malignancies are hematologic in children. Drug-induced pediatric Sweet syndrome is less common. In terms of infection, pediatric Sweet syndrome is most commonly proceeded by an upper respiratory tract or gastrointestinal (GI) infection but has also been reported to follow rotavirus infection, tonsillitis, otitis media, and HIV infection. Parainflammatory Sweet syndrome in children can be seen in lupus (systemic lupus erythematosus and subacute cutaneous lupus erythematosus), autoimmune hepatitis, Crohn disease, chronic granulomatous disease, primary T-cell immunodeficiency, and other primary immunodeficiencies. Paraneoplastic Sweet syndrome in children has been reported in Fanconi anemia, aplastic anemia, osteosarcoma, acute lymphocytic leukemia, myelodysplastic disorder, juvenile myelomonocytic leukemia, and acute myelocytic leukemia. Drug-related Sweet syndrome has been reported from granulocyte colony-stimulating factor, trimethoprim-sulfamethoxazole, all-trans retinoic acid, and azathioprine.

Sweet syndrome can proceed a diagnosis of malignancy by several months.

Pediatric Sweet syndrome is categorized into:
  • Neonatal Sweet syndrome (ages birth to 3 months).
  • Infantile Sweet syndrome (ages 3 months to 3 years).
  • Junior Sweet syndrome (ages 3-18 years).
Pediatric patients are less likely to report tenderness or pain compared to adults, and almost all pediatric patients will have leukocytosis, elevated erythrocyte sedimentation rate (ESR), and fever. Prodromal illness can be seen in just over one-half of cases. Arthralgia and arthritis are seen in over 20% of pediatric cases.

Pathergy is seen in up to a third of pediatric patients. Although still a minority of patients, it is slightly more common than in the adult population. When present, lesions will arise or worsen in sites of cutaneous injury, such as needle sticks. Fever may accompany or precede cutaneous involvement. The syndrome frequently includes extracutaneous manifestations such as fever, headaches, myalgias, malaise, arthralgias, and ocular inflammation. Other sites that may rarely be affected include the oral mucosa, liver (hepatitis), kidney (acute renal failure), lungs (pulmonary abscess and infiltrate), heart (pericarditis, aortitis), central nervous system (CNS) (encephalitis), GI tract (ileitis), lymphatics (lymphadenitis), musculoskeletal (myositis), and bones (sterile osteomyelitis). Hypotension and tachycardia are rare but can occur as a result of systemic inflammation.

Although the exact etiology is still unclear, abnormal cytokine expression and atypical neutrophil function are thought to contribute to the pathogenesis. A genetic predisposition may also contribute.

Sweet syndrome typically responds dramatically to systemic corticosteroids, but recurrences can be seen in up to a third of cases.


L98.2 – Febrile neutrophilic dermatosis [Sweet]

84625002 – Acute febrile neutrophilic dermatosis

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Differential Diagnosis & Pitfalls

  • Bacterial infections (Furunculosis, Cellulitis)
  • Sporotrichosis
  • Mycobacteria spp infections (typical and Atypical mycobacterial infection), including Mycobacterium marinum infection
  • Majocchi granuloma
  • Erythema nodosum – Primarily over the shins.
  • Acute hemorrhagic edema of infancy
  • Pyoderma gangrenosum – Begins as a pustule and evolves into a purulent ulcer with rolled borders. Has similar associations with IBD and malignancy.
  • Neutrophilic eccrine hidradenitis – Drug-induced toxicity of the eccrine coils 1-2 weeks following chemotherapy. Palmar involvement is more suggestive of this diagnosis. Patients typically lack fevers, but pathology may be required to differentiate these entities.
  • CANDLE syndrome
  • Erythema multiforme – Should display classic target lesions with 3 zones of color; favors acral surfaces. Oral involvement is common.
  • Bowel-associated dermatosis-arthritis syndrome – Pustular skin lesions and aseptic arthritis in bowel-bypass patients.
  • Majeed syndrome – Multifocal osteomyelitis, congenital anemia, and Sweet syndrome-like skin dermatosis.
  • Chronic granulomatous disease
  • Eosinophilic cellulitis – Involved skin is typically neither tender nor warm. Eosinophilia is present in 50% of individuals; neutrophilia is unusual. Eosinophils and flame figures can be seen on pathology.
  • Drug eruption general overview
  • Azathioprine hypersensitivity syndrome – Acute neutrophilic and systemic reaction after initiating azathioprine. See Drug-induced hypersensitivity syndrome.
  • Urticarial vasculitis
  • Erythema elevatum diutinum – A form of necrotizing vasculitis that primarily involves extensor surfaces.
  • Cutaneous small vessel Vasculitis – Presents symmetrically on the lower extremities; typically smaller than the plaques of Sweet syndrome.
  • Behçet syndrome – Rare, recurrent, and associated with oral or genital ulcers.
  • Bromoderma or Iododerma
  • Cutaneous leishmaniasis – Recent travel to endemic areas.
  • Lymphoma / Leukemia cutis
  • Metastatic cutaneous carcinoma
  • Sarcoidosis
  • Orf
  • Cat-scratch disease
  • Cutaneous anthrax
  • Coccidioidomycosis
  • VEXAS syndrome

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Drug Reaction Data

Below is a list of drugs with literature evidence indicating an adverse association with this diagnosis. The list is continually updated through ongoing research and new medication approvals. Click on Citations to sort by number of citations or click on Medication to sort the medications alphabetically.

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Last Reviewed:12/05/2022
Last Updated:07/18/2023
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Acute febrile neutrophilic dermatosis in Infant/Neonate
See also in: Cellulitis DDx
A medical illustration showing key findings of Acute febrile neutrophilic dermatosis : Fever, Asymmetric trunk or extremity distribution, Painful skin lesions, CRP elevated, ESR elevated, WBC elevated, Smooth nodules, Smooth plaques
Clinical image of Acute febrile neutrophilic dermatosis - imageId=1858339. Click to open in gallery.  caption: 'A well-demarcated, deep pink, pseudovesicular plaque over the medial clavicle.'
A well-demarcated, deep pink, pseudovesicular plaque over the medial clavicle.
Copyright © 2024 VisualDx®. All rights reserved.