Urticaria aka hives

Urticaria is a chronic inflammatory disease of the skin as a result of type 1 hypersensitivity reaction. It is characterized by transient erythematous itchy wheals over the entire body. The lesions are highly pruritic, raised above the skin surface, palpable and can be blanched. They involve variable regions of the body and dont have any particular shape or size.

If the patients complaints are for less than 6 weeks the condition is acute and Ig E involvement is expected. Complaint for more than 6 weeks is chronic and Ig G is involved.

There are several causative factors of the disease (10 I's and 3 P's!):

  • Idiopathic
  • Iatrogenic- Tetracyclines, Ace-inhibitors, Sulfa group drugs, NSAID's and Penicillins.
  • Ingestion: beef, fish, chicken, wheat, eggs, foods containing colored dyes,sea-food.
  • Injection: anti-diptheria serum, anti-tetanus serum, anti-snake serum.
  • Inhalation: pollen grains, smoke, dust.
  • Infections: Hepatitis B/C, H Pylori.
  • Infestaion: hook work, round worm.
  • Immune Disorders: SLE, rheumatoid arthiritis, chaugat's disease.
  • Irridation: x-rays, radiotherapy.
  • Internal malignancy: leukemia, lymphoma, sarcoma, carcinoma.

  • Psycogenic: stress
  • Physical: exposure to sea water, extreme weather conditions.
  • Physiological: pregnancy.

Pathogenesis:

Antibodies(IgE) are produced against the causative antigen. These antibodies recruit mast cells, basophils and eosinophils which consequently release mediators - histamine, serotonin, bradykinin, prostaglandins, leukotriens, kimases and tryptases. These mediators bind their respective mediators and causing the clinical manifestations of the disease.

This disease can manifest in four ways according to severity:

1) it is limited to the skin and the typical lesions are seen on examination.

2) Angioedema: most commonly associated with deficiency of C1 esterase inhibitor(controls clotting mechanism- factor 12). It appears as swelling mostly around the mouth/throat/tongue (muco-cutaneous junction) and may be itchy. Sensations are decreased as nerves may be compressed).

3) Anaphylaxis: skin, muco-cutaneous junction and systemic involvement. Causes respiratory distress and colicky abdominal pain. This stage is further divided into:
  • immediate: symptoms occuring within 2 hours of exposure and involving Ig E
  • delayed: symptoms occuring within hours and involving Ig G.
4)Anaphylactoid Reaction: this requires only 30 minutes to develope as it does not require the formation of immunoglobulins. the antigens directly attack mast cells to release the mediators and cause an anaphylactic reaction. If immediated care is not given patient may progress to anaphylactic shock and death. This reaction is mostloy caused by drugs or anti sera.


Diagnosis:
Dermograph- when the insulting agent is stroked in a linear fashion along the skin, the rash appears along the same region os contact.


Treatment:
Anti-histamines
Oral steroids- acute: short courses of high doses.
chronic: long courses of low doses.
Mast cell stabalizers
Immunosupressants
Immuno-modulators
IV Immunoglobulins
Plasmapheresis

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