Urticaria is a relatively common heterogeneous skin disorder that may be acute or chronic. The etiology is often difficult to determine, especially as it becomes chronic.
There are two types of Urticaria to classify such as:
A. Spontaneous Urticaria- It is the most common type of urticaria The symptoms and the signs of illness will be visible such as wheals , angioedema and itchiness. According to the duration, spontaneous urticaria classified into two types such as:-
1. Acute Spontaneous urticaria – It is characterized by spontaneously according wheals for at less than 6 weeks.
2. Chronic urticaria – It is characterized by spontaneously occurring wheals and itchiness for at least 2 days per week for a period of 6 weeks or more.
B. Inducible urticaria (also known as chronic physical urticaria) occur when triggered by specific physical stimuli
Pruritus(Itching) is the most predominate symptom. Other characteristic signs include wheals and flares that vary in size, with individual wheals usually resolving within 24 hours without residual hyper pigmentation.
Pathogenesis : Acute or chronic urticaria may occur as a result of mast cell and basophil release of bio active mediators, such as histamine and leukotrienes, after activation of either the innate or adaptive immune system.
Therefore activation of mast cells by particular IgE, IgG or IgM antibody results urticaria activates the classical complement pathway. Other mediators (neuropeptides such as substance P, calcitonin gene related peptide and neurokinin A) and medications such as opiates can also activate mast cells or basophils through specific receptors and for cyclooxygenase inhibitors (i.e., ASA, NSAIDS) to induce hives through non-IgE mediated pathways.
Treatment lies in removing the source of allergy. Since common causes of acute urticaria include infection and food allergy, investigation for these underlying causes should be guided by the history and physical examination. Detailed evaluation needs to be done for patients with chronic urticaria.
Antihistamines form the baseline for management. Newer treatment options include usage of Omalizumab