Hives (Urticaria): Definition and symptoms,Causes,Types,Diagnosis

Hives, also known as urticaria, affects about 20 percent of people at some point in their lives. Urticaria is one of the most common dermatological and allergic skin reactions and, compared to other diseases, it is easily recognizable by patients and doctors. , the disease is very complex in terms of causes, clinical manifestations and therapy

Urticaria is a vascular reaction of the skin characterized by evanescent edematous plaques (bruises). Angioedema differs only in the fact that edema extends into the deep dermis and subcutaneous tissue. About 15% of the population develops this problem at some point in life

Definition of Hives 

Hives are defined by the appearance of hives (urticaria or individual hives) of any size and configuration on any part of the skin. The hives are made up of a circumscribed, slightly raised, erythematous, generally itchy and edematous swelling of the upper skin tissue which disappears in a few minutes or hours, leaving the substantially normal-looking skin unchanged (restauratio ad integrum)

Urticaria is defined by the welt characterized by three typical aspects:
• A central welt with surrounding reflex erythema
• Associated itching
• Its fleeting nature, with the skin returning to its normal appearance, generally within a few minutes and rarely after a few hours

What normally happens when you have urticaria?

Almost all hives disappear in a couple of days up to a week. Sometimes there are people who experience inflammation and itching that occur and then disappear for several years only to return

These two types of urticaria are distinguished only by the duration of the disease. By definition, acute urticaria lasts for up to 6 weeks (some authors use four weeks as a cut line), but can recur intermittently in weeks or months. Chronic urticaria is defined as the duration of over 6 weeks, with a continuous or recurrent pattern, depending on the frequency of urticaria episodes

• Acute urticaria: acute urticaria is characterized by scattered bruises that are larger than 1 cm and rarely only 2 to 3 mm in diameter, with surrounding erythema and associated itching. Angioedema can be prominent in some patients. In about 15% of patients, systemic reactions can be associated with moderate nausea and dyspnoea

• Chronic urticaria: with the exception of the duration of the disease, there are no differences between acute and chronic urticaria as regards the clinical aspect. Angioedema can occur with or without associated bruising

Histopathology

The usual ephemeral urticaria lesions show very few distinctive pathological features on light microscopic examination of skin biopsies. The edema of the papillary and reticular dermis can be so intense as to cause a separation of the epidermis from the dermis. The small venules in the upper dermis are dilated, but the capillaries of the subpapillary plexus can narrow due to the pressure of severe skin edema. A cellular infiltrate is absent in early lesions. Electron microscopy shows mast cell degranulation or only specific intracellular granules of swollen mast cells, brighter for electrons

Immunoglobulins, mast cells, mast cell mediators

In the skin, mast cells are found all over the dermis, but with a fondness for The proximity of the appendages, including pilosebaceous follicles, nerve fibers and blood vessels. The turnover of dermal mast cells is slow
Mast cells are generally recognized as the main cell type for initiating immediate hypersensitivity reactions (type I) and more recently as a cell that also contributes to innate and acquired immunity and to the remodeling of tissues. Mast cells can be activated to release mediators such as histamine from both IgE-dependent and IgE-independent stimuli and are an integral part of urticaria and associated angioedema. The experimental challenge of an IgE sensitive host with allergen reveals two phases of the subsequent immediate hypersensitivity reaction

Causes of Hives

Main categories of stimuli or causes of the urticaria reaction

• Food proteins, preservatives, dyes: food does not consist only of basic nutrients in the form of fats, carbohydrates and proteins, but also contains vasoactive amines, histamine liberators, toxic products of bacteria or mold contaminants, antibiotics, spices, flavorings, dyes. and preservatives. Chronic urticaria due to food intolerance reactions is mainly based on pseudo-allergic mechanisms. In acute urticaria, type I allergic reactions mediated by IgE are rare, but should be excluded if any allergens are ingested shortly before the onset of urticaria. Food reactions are caused by allergens that are resistant to acids, 18-36 kD glycoproteins and are associated with the production of IgE and IgG to allergens, and the latter has no pathological importance

• Medicines: allergic mechanisms are involved in less than 25% of drug reactions and manifest themselves clinically as urticaria, angioedema and rarely as anaphylactic shock. Pharmacological reactions occur mainly as morbilloform or horticular rashes, although mixed types of reactions may also occur. Antibiotics are the most frequent cause of anaphylactic reactions, with penicillin the most frequent. According to the literature, up to 7% of the general population is sensitized and hives account for up to 40% of reactions to penicillin

• Inhalant allergens: reticular reactions to inhaled substances are relatively rare. In contrast, asthma and rhinitis are the most common manifestations in the primary contact organs. The reactions are particularly frequent in highly sensitized patients with allergies to pollen and drugs, workers and smokers exposed professionally. Cigarettes can also induce urticaria, with three different allergens identified so far. In cigarette smoke and aqueous extracts of hardened tobacco leaves, an 18 kD glycoprotein has been found to cause positive skin test reactions in a third of smokers and nonsmokers

• Infections and infestations: considering the almost continuous exposure of the individual to the antigens of infectious agents, the low incidence of urticaria reactions to them is surprising. This may be due to the fact that microorganisms tend to stimulate the production of IgG antibodies instead of IgE. Despite their high frequency, bacteria rarely cause urticaria reactions, probably because they induce the synthesis of IgG instead of IgE. Furthermore, there is probably also an increase in allergic tolerance in the adult population due to frequent and intense previous exposure, while children still show relatively frequent reactions

Hives are a rare manifestation of allergy to inhalants. Asthma and rhinitis are much more frequent and during exposure to industrial allergens, contact eczema is even more frequent. However, there are well documented clinical cases and urticaria studies induced by respiratory exposure

• Internal diseases: the association of urticaria and internal disease is rare. Two types of disease seem to distinguish themselves, the so-called autoimmune or connective tissue diseases and dysproteinemias with or without malignant tumors

Autoimmune diseases: SLE, Still's disease, rheumatic fever, polymyositis:

• Dysproteinemias: IgM-paraproteinemia (Schnitzler syndrome) dysproteinemias associated with cold urticaria
• Neoplasms: Hodgkin's disease, lymphatic leukemia, non-Hodgkin lymphomas, polycythemia vera, carcinoma of the colon and rectum
• Various other diseases: sarcoidosis, amyloidosis (+ deafness = Muckle-Wells syndrome)

• Malignancy

• Hormones: urticaria due to allergic reactions to endogenous hormones are very rare, while hormonal drugs are a more likely cause. Acute or chronic urticaria occurs rarely in association with hormone therapy. Anaphylactic reactions to endogenous hormones and urticaria in association with endocrine disorders are even less frequent

• Insulin and other hormones
• Thyroid disease
• Progesterone and Pregnancy

• Physical and mental stress: in clinical practice, patients whose hives develop or exacerbate during stress can be repeatedly observed. In several larger studies, psychological factors and stress have been identified as the main cause of urticaria in 11.5% of patients and 24-51% as an aggravating factor

• Physical agents

• Contactants the pollutants

Types of Hives

a) Acute urticaria This includes isolated attacks of urticaria lasting <6 weeks, although the mainly idiopathic systemic causes include viruses, drugs and type I hypersensitivity reactions

• Continuous acute urticaria
• Acute intermittent urticaria

b) Chronic urticaria attacks last> 6 weeks and the frequency may be intermittent or persistent every day or urticaria every day. Chronic idiopathic urticaria and autoimmune urticaria fall into this category

• Chronic continuous urticaria
• Chronic recurrent urticaria

c) Special types of urticaria

• Cholinergic urticaria (generalized rash of urticaria in response to exercise, increased body temperature or emotional provocation): may be accompanied by angioedema; Exercise-induced anaphylaxis can occur rarely
• Physical urticaria
• Localized response of skin contact urticaria to contact with an allergen, but the response may also be non-allergic (pseudo-allergic): it can be associated with angioedema
• Urticarial vasculitis (a chronic urticaria with histological evidence of vasculitis in the affected skin and which may be idiopathic or secondary to systemic disease): may be associated with angioedema
• Urticaria pigmentosa (mastocytosis) (cutaneous mastocytosis) (urticaria associated with hyperproliferation of dermal mast cells): rarely associated with angioedema


Classification of urticaria, based on possible pathogenic mechanisms:
I Immunoglobulin-dependent urticaria (mainly IgE)

• Atopic diathesis
• Specific antigen sensitivity (drugs, pollen, food, contaminants, insect poisons)
• Physical urticaria
• Dermographic urticaria
• Cold urticaria
• Solar urticaria
• Cholinergic urticaria

II urticaria mediated by complement

• Hereditary angioedema
• Acquired angioedema
• Necrotizing vasculitis
• Heat urticaria
• Serum sickness
• Reactions to blood products or substitutes

III. Nonimmune urticaria

A. Direct mast cell release agents

• Opioids
• Antibiotics
• Curare
• Radiocontrast media
• Chemical contactants

B. Intolerance reactions

• Aspirin and nonsteroidal anti-inflammatory agents
• Azodi and benzoates

IV. Mast cell disease, urticaria pigmentosa

V. Idiopathic urticaria

Diagnosis of Hives

The goal of a diagnostic measure is to distinguish the type of urticaria and the especially cause.  Hives are generally diagnosed by taking the patient's history along with the physical exam, without the need for research to confirm the diagnosis

Acute urticaria does not require extensive diagnostic procedures. The urticaria activity score is a useful tool for evaluating urticaria. Complete blood count, globular sedimentation rate and C-reactive protein are important research for the diagnosis of urticaria infections

The autologous serological skin test is a simple office procedure for the diagnosis of self-reactive urticaria. The closed tip of the pen is a simple test to diagnose dermographism

Some tests carried out on patients with urticaria:

• Food skin test; Here is how the skin reacts to different dietary compositions after ingestion or contact
• Safely stop all concomitant medications to see the body's response; if there is a reduction in attacks
• Measurement of thyroid gland functions; This includes the presence of anti-thyroid peroxidase and anti-thyroglobulin antibodies. NB // More than 22% of intensive care cases are associated with Hashimoto's thyroiditis disorders
• Get a complete blood cell count and globular sedimentation rate; CBC and ESR
• Chest X-ray: This is done to examine the inside of the body