Acute generalized exanthematous pustulosis

Background

• T-cell mediated rash with systemic features
• >90% of cases attributable to a medication (usually an antibiotic)
• Mortality rate of ~5%

Clinical Features

Acute generalized exanthematous pustulosis

• Onset 1-5 days after starting causative medication
• Rash:
  • Large areas of edematous erythema with numerous small, non-follicular pustules
  • Predominantly affects main body folds and upper trunk, but can involve face
  • NO mucous membrane involvement (in contrast to SJS/TEN)
• Systemic findings:
  • Fever
  • Leukocytosis, specifically neutrophilia
  • +/- Facial swelling
  • +/- Hepatitis
  • +/- Eosinophilia

Differential Diagnosis

Erythematous rash

• Positive Nikolsky’s sign
  • Febrile
    • Staphylococcal scalded skin syndrome (children)
    • Toxic epidermal necrolysis/SJS (adults)
  • Afebrile
    • Toxic epidermal necrolysis
• Negative Nikolsky’s sign
  • Febrile
    • Toxic shock syndrome
    • Kawasaki disease
    • Scarlet fever
    • DRESS syndrome
    • Cellulitis
    • Acute generalized exanthematous pustulosis
  • Afebrile
    • Alcohol intoxication
    • Anaphylaxis
    • Cellulitis
    • Dermatitis (multiple types)
    • Drug rash
    • Erysipelas
    • Erythema multiforme
    • Exfoliative erythroderma
    • Scombroid
    • Vancomycin infusion reaction

Evaluation

Workup

• Clinical diagnosis
• CBC
• BMP
• LFTs

Table of Severe Drug Rashes

Charateristic	DRESS	SJS/TEN	AGEP	Erythroderma
Image
Onset of eruption	2-6 weeks	1-3 weeks	48 hours	1-3 weeks
Duration of eruption (weeks)	Several	1-3	<1	Several
Fever	+++	+++	+++	+++
Mucocutaneous features	Facial edema, morbilliform eruption, pustules, exfoliative dermattiis, tense bullae, possible target lesions	Bullae, atypical target lesions, mucocutaneous erosions	Facial edema, pustules, tense bullae, possible target lesions, possibl emucosal involvement	Erythematous plaques and edema affecting >90% of total skin surface with or without diffuse exfoliation
Lymph node enlargement	+++	-	+	+
Neutrophils	Elevated	Decreased	Very elevated	Elevated
Eosinophils	Very elevated	No change	Elevated	Elevated
Atypical lymphocytes	+	-	-	+
Hepatitis	+++	++	++	-
Other organ involvement	Interstitial nephritis, pneumonitis, myocarditis, and thydoiditis	Tubular nephritis and tracheobronical necrosis	Possible	Possible
Histological pattern of skin	Perivascular lymphocytcic infiltrate	Epidermal necrosis	Subcorneal pustules	Nonspecific, unless reflecting Sezary syndrome or other lymphoma
Lymph node histology	Lymphoid hyperplasia	-	-	No, unless reflecting Sezary syndrome or other malignancy
Mortality (%)	10	5-35	5	5-15

Management

• Stop inciting agent
• IVF- treat similar to fluid resuscitation in burns
• Wound care, infection control

Disposition

• Admit

See Also

• Erythematous rash
• Stevens-Johnson syndrome and toxic epidermal necrolysis
• DRESS syndrome