Urticaria is one of vascular Dermatoses. Many People have suffered
urticaria caused by allergy reaction.
Urticaria is a vascular reaction dne by erytheatous skin or whitish skin
due to local intercellular which is limited to skin or mucosa only. The commonly
seen entity of urticaria, or hives, can be acute or chronic and due to known or
unknown causes..
Numerous factors, both immunologic and nonimmunologic, can be involved
in its pathogenesis. Nonimmunologic factors that can release histamine from
these cells include chemicals, various drugs (including morphine and codeine),
ingestion of lobster, crayfish, and other foods, bacterial toxins, and physical
agents. Examples of the type caused by physical agents are the linear wheals
that are produced by light stroking of the skin, known as dermographism.
Immunologic mechanisms are probably involved more often in acute than
in chronic urticaria. The most commonly considered of these mechanisms is the
type I hypersensitivity state that is triggered by polyvalent antigen bridging
two specific immunoglobulin E molecules that are bound to the mast cell or
basophil surface.
CAUSES. After careful questioning and investigation, many cases of
hives, particularly of the chronic type, are concluded to result from no apparent
causative agent. Other cases, mainly the acute ones, have been found to result
from the following factors or agents:
- Drugs or Chemicals. Penicillin and derivatives are probably the most common causes of acute hives, but any other drug, whether ingested, injected, inhaled, or, rarely, applied on the skin, can cause the reaction
- Foods. Foods are a common cause of acute hives. The main offenders are seafood, strawberries, chocolate, nuts, cheeses, pork, eggs, wheat, and milk. Chronic hives can be caused by traces of penicillin in milk products.
- Insect Bites and Stings. Insect bites, stings from mosquitoes, fleas, or spiders, and contact with certain moths, leeches, and jellyfish cause hives.
- Physical Agents. Hives result from heat, cold, radiant energy, and physical injury. Dermo-graphism is a term applied to a localized urticarial wheal produced by scratching the skin in certain people. Dermographism is commonly overlooked as a cause of the patient's “welts” or vague itching.
- Inhalants. Nasal sprays, insect sprays, dust, feathers, pollens, and animal danders are some offenders.
- Infections. A focus of infection is always considered, sooner or later, in chronic cases of hives, and in unusual instances it is causative. The sinuses, the teeth, the tonsils, the gallbladder, and the genitourinary tract should be checked.
- Internal disease. Urticaria has been seen with liver disease, intestinal parasites, cancer, rheumatic fever, and others.
- “Nerves.” After all other causes of chronic urticaria have been ruled out, there remain a substantial number of cases that appear to be related to nervous stress, worry, or fatigue. These cases benefit most from the establishment of good rapport between the patient and the physician.
- Contact Urticaria Syndrome. This uncommon response can be incited from the local contact on the skin of drugs and chemicals, foods, insects, animal dander, and plants.
- Cholinergic Urticaria. Clinically, small papular welts are seen that are caused by heat (hot bath), stress, or strenuous exercise.
Patients
with chronic urticaria present a major problem in diagnosis and management.
These patients are often subjected to detailed and expensive medical
evaluations that usually prove unrewarding. Recent studies have demonstrated
the value of a complete history and physical examination followed by the
judicious use of laboratory studies in evaluating the results of the history
and physical examination.
