Small group; drug eruptions

Question 1

How long do individual urticaria lesions last?

Answer 1

Lesions are migratory and individual lesions last less than 24 hours, though the urticarial reaction as a whole may last longer

Question 2

What causes urticaria?

Answer 2

• **hives
• caused by IgE-mediated immediate hypersensitivity
• most cases of acute urticaria are idiopathic
  
  • most common identified cause is upper respiratory infection
  • drugs cause only 10% of cases.

Question 3

How do you treat urticaria?

Answer 3

**oral antihistamines;

• Non-sedating H1 antihistamines
  
  • loratadine
  • cetirizine
  • fexofenadine
• Sedating classic H1 antihistamines
  
  • diphenhydramine
  • hydroxyzine

Question 4

What is an exanthematous drug eruption?

Answer 4

• also called morbilliform drug rashes
• the most common cutaneous drug eruption
• a manifestation of type IV (delayed) hypersensitivity
• monomorphic (individual lesions look very similar to one another) macules and thin papules start on the face and trunk, then spread to the extremities
• lesions are usually pruritic and a low grade fever may be present, but the reaction is limited to the skin

Question 5

What is DRESS?

Answer 5

• “drug reaction with eosinophilia and systemic symptoms”
• resembles that of exanthematous drug eruptions, but it is commonly associated with fever, facial edema, enlarged lymph nodes, and arthralgias
• systemic involvement; liver, myocarditis, pneumonitis, nephritis, thyroiditis, and brain
• fatal in 10% of cases, so prompt recognition and discontinuation of the suspected drug cause is imperative
  
  • treat with systemic corticosteroids

Question 6

What is Erythema multiforme (EM)?

Answer 6

• target lesions characterized by 3 or more color zones and a dusky red or purple center
• arise abruptly on acral areas such as the hands, feet, elbows, and knees and last up to 2 weeks (involvement of the ocular, oral, and genital mucosa can be seen in some cases)
• Infectious triggers (most commonly herpes simplex virus) are responsible in 90% of cases while drug causes make up <10%
• self resolves

Question 7

What is SJS/TEN?

Answer 7

• Stevens-Johnson syndrome (SJS)/ toxic epidermal necrolysis (TEN)
• preceded by a prodrome of fever, malaise, and upper respiratory symptoms before the onset of cutaneous lesions
• painful red patches evolve rapidly into bullae and areas of necrosis (skin easily sloughs off; sepsis common)
• commonly caused by allopurinol, NSAIDs, sulfa drugs, anticonvulsants (lamotrigine, carbamazepine, phenobarbital, phenytoin), and antibiotics

Question 8

What is vasculitis?

Answer 8

Inflammation and destruction of blood vessels, either arteries or veins

Question 9

What is LCV?

Answer 9

• Leukocytoclastic vasculitis (palpable purpura)
• a histologic diagnosis; small vessel vasculitis of the skin when neutrophils are the predominant inflammatory cell seen on biopsy
• drug (antibiotics) hypersensitivity, infections (upper respiratory, group A streptococcal, hepatitis B and C, HIV) and ~50% of cases are idiopathic

Question 10

What is Henoch-Schonlein purpura (HSP)?

Answer 10

• small vessel vasculitis that predominately affects children
• IgA immune complexes (on direct immunofluorescence)
• commonly triggered by infections (group A streptococcal infection and other upper respiratory infections)
• palpable purpura on the skin, especially on the buttocks and lower extremities
  
  • arthritis, abdominal pain, gastrointestinal bleeding, and nephritis possible
• self-limited and resolves over the course of 2-4 weeks