It's winter now, and there's a long line of outpatients in dermatology department. What skin disease occurs more often in winter and what is reason? Once "acquired", how to deal with it?
Some skin diseases occur only in winter, such as frostbite, cold urticaria, etc. Of course, in addition to them, pruritus, erythema nodosum, herpes zoster, ichthyosis, herpes simplex, etc. often occur.Today we will talk about cold urticaria
[First, what is urticaria? 】
Urticaria is a temporary, itchy, vasoreactive skin disease characterized by reddening of skin and mucous membranes and blistering.
This is a local reaction of skin edema caused by expansion and increased permeability of small blood vessels in skin and mucous membranes.
This is a common condition, and between 15 and 25% of people will experience hives at least once in their lives. The prevalence of idiopathic urticaria is 0.5% to 1.5%.
[Etiology and pathogenesis] (this paragraph is not easy to understand, you may want to read it carefully)
The etiology is complex, physical and chemical environmental factors can cause disease, such as infection, food, drugs, temperature changes, dust, pollen, etc.;
Self-diseases, such as atopic constitution, patients with autoimmune diseases are also prone to disease.
By pathogenesis, urticaria can be divided into immune-mediated and non-immune-mediated urticaria.
Immune mechanisms are divided into three types: allergic, complement-mediated and autoimmune.
Most allergic patients have Type I allergies mediated by 1gE. Specific IgE binds to receptors on surface of mast cells or basophils, causing degranulation of mast cells and basophils, release of histamine and other mediators, increased vascular permeability, telangiectasias, smooth muscle contraction, increased secretion of glandular body, resulting in a number of symptoms such as skin and mucous membranes, gastrointestinal tract and respiratory tract. Type II allergic urticaria is more common in patients with selective IgA deficiency and can occur with transfusion reactions, causing anaphylactic shock, etc. Type III hypersensitivity is urticarial vasculitis, often Because there are many antigens, antigen-antibody immune complexes deposit on blood vessel wall, activate complement, and cause mast cells and neutrophils to release histamine and other inflammations. media, causing increased permeability and edema of vessel wall. A solitary skin lesion in vasculitic urticaria usually lasts more than 24 hours, in contrast to usual type, which usually disappears within 24 hours.
Autoimmune urticaria includes 2 situations:
①The patient's blood contains its own anti-IgE IgG antibodies, which can bind to IgE bound to surface of mast cells, cause mast cell degranulation and cause blisters;
②The patient's blood contains its own IgG antibodies to Ige Fc receptors, which directly bind to high-affinity Fc Ige receptors to degranulate mast cells. Non-allergic urticaria is mainly caused by histamine releasing agents. Various drugs such as atropine, morphine, quinine, aspirin, pilocarpine, pethidine, polymyxin B, codeine, tween-80, vitamin B1, tubocurarine and various animal toxins. There are also certain foods such as fish, shrimp, meat, eggs, mushrooms, strawberries, eggplant, bamboo shoots, spinach, apples, plums, yeast, salicylic acid, citric acid, and other nutritional supplements. Urticaria associated with abnormal metabolism of arachidonic acid,for example, urticaria caused by aspirin and other non-steroidal anti-inflammatory drugs may be due to abnormal arachidonic acid metabolism rather than an allergic reaction.
The mechanism of urticaria is still unknown.
Conscious itching, can sometimes be accompanied by fever, swelling and pain in joints, headache, nausea, vomiting, abdominal pain, diarrhea, chest tightness, shortness of breath, wheezing, palpitations and other systemic symptoms. Physical examination revealed blisters of various sizes. Depending on whether wheal occurs spontaneously or must be caused by physical factors, it can be divided into spontaneous urticaria and physical urticaria. Spontaneous urticaria is divided into two types: acute and chronic. Onset more than 2 days a week - acute urticaria if history is less than 6 weeks, and chronic urticaria - more than 6 weeks. Non-weekly onset, with longer intervals between attacks - intermittent urticaria. Most solitary wheals of spontaneous urticaria disappear within 24 hours. Urticarial vasculitis should be suspected if it does not recur for more than 24 hours. If fever, arthralgia, proteinuria, and an elevated white blood cell count occur simultaneously, this is called a serum sickness-like syndrome.
[What is cold urticaria? 】
Cold urticaria is a type of special urticaria
Cold urticaria: divided into two types: acquired and hereditary.
Appears as blisters that appear a few minutes after exposure to cold. If cold urticaria occurs while swimming, it can lead to death by drowning. Drinking cold drinks can also cause swelling in throat. This type can be diagnosed with an ice cube test, i.e. a small ice cube is placed on skin of forearm for 5 minutes and diagnosis can be confirmed if a local blister is induced. Hereditary cold urticaria is a familial autosomal dominant inheritance, more common in women, onset usually begins in childhood, and generalized wheals appear hours after exposure to cold, which may be accompanied by chills, fever, headache, joint pain, and increased white blood cells, test negative for passive transfer.
Serum cryoglobulin, cold fibrinogen, and antinuclear antibodies in patients with cold urticaria may be positive or negative.
Western medicine usually uses antihistamines and leukotriene antagonists, or a combination of two.
In some patients, low doses of corticosteroids are effective.
Antibiotics such as penicillin or tetracycline may completely relieve or improve symptoms in some patients.
For patients with cold urticaria, in initial period, “desensitization therapy” can be carried out, that is, a gradual transition from washing face with warm water to washing face with cold water, and after an adaptation period, exposure to cold water or cold air will help to avoid allergic reactions. This method is simple and easy to use and is effective for most patients, but temperature of water should not be too low and should not be so low that it appears to be cold, otherwise it may be counterproductive.
The treatment of primary cold urticaria is relatively difficult. Treatment of secondary cold urticaria requires treatment of underlying disease. If primary disease improves, urticaria will also improve.
Chinese medicine treatment of cold urticaria
Traditional Chinese medicine believes that this disease is caused by wind-chill attack and disharmony, so strengthening body to dissipate cold and reconcile camp and health are main principles of treatment.