Sweet's syndrome

Background

Normal dermal anatomy.

• Acute febrile neutrophilic dermatosis
• Rare skin condition
• Usually affects age 30-60, but can happen in any age group
• Classic Sweet syndrome affects women > men
• Unclear pathologenesis, but possibly factors include hypersensitivity reaction, cytokine dysregulation, or genetic susceptibility

Etiologies

• Classical Sweet syndrome, usually secondary to:
  • Infection: Typically 1 to 3 weeks following upper respiratory infection or gastrointestinal infection
  • Inflammatory bowel disease: Crohn's disease or ulcerative colitis
  • Pregnancy
• Malignancy-associated Sweet syndrome
  • Hematologic (~85%), most commonly acute myeloid leukemia
  • Solid tumor (~15%), most commonly carcinoma of GU organs, breasts, GI tract
• Drug-induced Sweet syndrome, most commonly granulocyte-colony stimulating factor (G-CSF)
  • Typically 2 weeks after drug exposure in patient without prior exposure
• Fever and rash

Clinical Features

Sweet's Syndrome of index finger

Sweet's syndrome with lesions distributed in a sporotrichoid pattern.

Targetoid papules and plaques in Sweet's syndrome

• Cutaneous disease
  • Painful, edematous, and erythematous papules, plaques, or nodules
  • Often exhibit a mamillated surface with significant superficial dermal edema leading to pseudovesicular quality
  • Usually upper extremities > lower extremities, with asymmetrical distribution
• Extracutaneous disease: neutrophilic infiltration of organ systems
  • Ocular infiltration (most common): conjunctivitis, scleritis, keratitis, iritis
  • Muscular system: arthralgias, arthritis, myalgia
  • Less commonly CNS, cardiovascular system, pulmonary system, liver, intestines, kidneys, bones
• Fever and leukocytosis

Differential Diagnosis

• Infectious
  • Adenovirus
  • Arbovirus
  • EBV
  • Ehrlichiosis
  • Enterovirus
  • Fifths disease
  • HHV 6
  • Leptospirosis
  • Lyme
  • Meningococcemia
  • Mycoplasma
  • Parvovirus (B19)
  • Primary HIV
  • Psittacosis
  • Rickettsia
  • Rubella
  • Rubeola
  • Secondary syphilis
  • Streptobacillus moniliformis
  • Typhoid fever/typhus

• Noninfectious
  • Acrodermatitis enteropathica
  • Allergy
  • Dermatomyositis
  • Erythema marginatum
  • Erythema multiforme
  • Lupus
  • Serum sickness
  • Sweet's syndrome

Evaluation

Workup

• CBC
  • leukocytosis with neutrophilia
  • anemia (more common in malignancy or drug associated)
  • platelet abnormalities (more common in malignancy or drug associated)
• Complete metabolic panel
• Urinalysis
• ESR
• CRP

Diagnosis

Major criteria

• Abrupt onset painful erythematous plaques or nodules
• Histopathological evidence of neutrophilic infiltrate without evidence of leukocyoclastic vasculitis

Minor criteria

• Fever
• Associated malignancy, IBD, pregnancy, preceding URI, preceding GI infection
• Improvement with treatment with systemic steroids
• Abnormal labs (3+ of following): ESR > 20, elevated CRP, leukocytosis, neutrophilic predominance

Management

• Systemic glucocorticoids - prednisone 0.5 - 1.0 mg/kg per day with taper after symptom improvement
• Topical and intralesional corticosteroids - limited data, mostly used as adjunct, for mild disease (<5% BSA), or absence of systemic symptoms
• Alternatives agents include colchicine, dapsone, potassium iodide if steroids contraindicated
• Referral to dermatology for biopsy
• Evaluation for malignancy (if clinically appropriate)
  • If other concerning symptoms and no other explanation for diagnosis

Disposition

• Usually outpatient with close dermatology follow up

External Links

• https://dermnetnz.org/topics/acute-febrile-neutrophilic-dermatosis/