CLINICAL MANIFESTATIONS OF ALLERGY : SKIN
Skin is the largest organ, covering the entire body. It is the ultimate vessel for human body; which receives and transports, accepts and expels according to the body’s needs.
In addition to serving as a protective shield against heat, light, injury, and infection, the skin also:
- Regulates body temperature
- Stores water and fat
- Is a sensory organ
- Prevents water loss
- Prevents entry of bacteria
ALLERGIC MANIFESTATIONS OF SKIN
ECZEMA The word “Eczema” is a Greek word, which means to “boil out”.
Basically, the factors combining to cause Dermatitis and Eczema, are ENDOGENIC (internal) which render the skin allergic or vulnerable and secondly the EXOGENIC (external), i.e., the invasion by an allergen through contact, inhalation or ingestion.
Truly speaking there is no eczematous patient, as the exciting factors have to be established. Once the skin has been irritated and sensitized, it becomes prone to further insults. Scratching, chemical trauma, climatic strains and psychogenic stresses keep the process going, with the result that it becomes chronic. In such cases there is usually a FAMILY HISTORY of allergy e.g. Urticaria, Allergic Rhinitis, Asthma etc.
There is a multitude of allergens that cause Eczema. The most common ones are:
- Irritants: Physical, chemical or electrical
- Sensitizers : Plants, cosmetics, clothing, ointments and occupational hazards, alkalis like soap
- Climate: Temperature and humidity e.g. photodermatitis
- Drugs: Given for the disease or otherwise. Systemically administered drugs can produce a number of morphologically distinct cutaneous eruptions. Macular, maculopapular lesions and Urticaria are the most undesirable effects caused by drugs along with itching, fever, eosinophilia etc…
Mental and emotional conflicts
Eczema is an inflammation of the skin which may cause dryness, flakiness, heat and most importantly, itching. It is usually said that in Dermatitis “it is an itch that rashes rather than a rash that itches”. It is a pruritic papulovesicular process. First, there is superficial inflammation of the epidermis then there is vesication, which causes mild to severe itching. It then goes through the stages of formation of watery discharge, crusting and finally scaling. Ultimately, it heals without any scars but if the Eczema becomes chronic there is lichenification of the skin, i.e., the skin becomes hard and leathery.
URTICA or HIVES
Urticaria or Hives are itchy, burning eruptions that appear on the skin as an indication of an allergic sensitivity to various allergens.
The development of Urticaria occurs when the body releases histamines into the blood stream or tissues as an allergic response causing widening of the capillaries thereby allowing the plasma to escape through its walls resulting in raised eruptions on the skin surface.
The most common allergies are:
Food: Food allergy due to some item that has been consumed within a day or two will give rise to generalized itching, abdominal cramps and loose stools. The common (food) allergens are eggs, nuts, wheat, chocolate, cocoa, prawn, crabs, nuts and food dyes and additives etc.
Sprays and inhalants.
Dust and Pollutants.
Drugs: Many Drugs, vaccines and hormone preparations can precipitate Urticaria.
Physical factors: e.g. cold, heat, pressure, and exertion.
Urticaria appears as red or white blotches on the skin accompanied by itching and burning. They may disappear as suddenly as they came or they may last for several days.
Severe itching preceeds the attack.
Eruptions of various sizes usually appear.
In a few minutes, eruptions may develop, spread, and coalesce to form larger hives.
Any part of the body may be affected.
The most serious complication is the development of giant hives known as Angio-neurotic oedema. This condition appears on eyelids, lips or tongue accompanied by swelling. When the swelling is internal especially in the air-passages it can lead to obstruction in breathing.