Urticaria

Urticaria is rapid onset of wheal and flare cutaneous lesion involving superficial dermis resulting formation of central swelling with or without surrounding erythema and associated with pruritis lasting for 24 hours.

Classified as:

1. Ordinary: acute and chronic diffrentiated by 6 weeks duration
   
   • Autoimmune
   • Allergic
   • Drugs
   • Infection
   • Idiopathic
2. Special
   • Physical
   • Urticarial vasculitis
   • Contact
   • Angioedema with wheals
   • Recurrent (recurrent episodes each episodes lasting 6 weeks)

Causes: 

• Infection: Viral, H.pylori, mycoplasma, hepatitis, paracitic
• Drugs: B-lactam antibiotics, NSAIDS, Aspirin, ACEIs, Opiates
• Food: peanuts, pork, buff meat, tomatos, milk products, eggs
• Inhalants: pollens, mods, duts, mites
• Emotional stress
• Systemic factors: SLE, thyroid disorders, mastocytosis

Pathogenesis:

Causative agents enters host -----> Immune cells activated and release mediators -------> mast cells release cytokines and mediators responsible for symptoms

Clinical Features:

Symptoms:

• itching
• circular red rashes
• swelling of body parts
• constitutional symptoms: fever, malaise, headache, pain, arthralgia, dissiness, syncope

Signs:

• erythematous macules; pale pink wheals with surrounding flare
• last for around 24 hours
• can be circular, annular, serpenginous, bizzare
• swelling of lips, mouth, legs, hands or any other body parts
• associated signs of constitutional symptoms

Investigation: 

• Baseline Routine examination: including ESR, CRP, S. uric acid, LFT
• Special investigation:
  • skin prick test
  • fluorescence enzyme immunoassay
  • serum raioallergosorbent
  • histopathology in case of urticarial vasculitis
  • low C1-INH, C4 indicates heriditary angioedema

Treatment:

General measures:

• conselling and avoidance of aggravating factors
• reassure patient, educate about its relapse and recuurance

Special Measure:

• First line therapy:
  • H1 blocker 
    • 1st generation: promethazine, cyclizine, chlorphenaramine
    • 2nd generation: cetrizine, loratidine, terfenadine
    • 3rd generation: levocetrizine, fexofenadine
  • H2 blocker: Cemitidine, Ranitidine
• Second line therapy: Adrenergic drugs(terbutaline, adrenaline), oral steroids
• Third line therapy: Immunomodulators, IV IG, cyclosporine
• in case of emergency: adrenaline