【 Etiology and Pathogenesis 】 The etiology of this disease is complicated.
Systemic itching is often accompanied by some systemic diseases, such as diabetes, uremia, hepatobiliary diseases, visceral tumors, hematological diseases, thyroid diseases, allergic diseases, intestinal parasites, habitual constipation, irregular menstruation, pregnancy and mental anxiety, and nervous system diseases. The itching of Hodgkin's disease is persistent and sometimes accompanied by burning sensation. The incidence of pruritus is 10% ~ 25%, which is the first symptom of 7% patients, but the cause is unknown. Patients with polycythemia above 1/3 have itching, which is mostly caused by temperature change and has nothing to do with histamine level; 20% ~ 50% patients with obstructive jaundice have itching, and the severity of itching is sometimes parallel to the concentration of bile salts in the skin. Because the level of carboxyl amino acids in patients' central nervous system is increased and naloxone is effective, itching may be caused by central mechanism. Uremic patients also have common unbearable itching all over the body, which may be related to some metabolic imbalances; Visceral tumors can be seen in 3% ~ 47% patients with systemic itching. Abnormal skin condition and function (such as dryness and atrophy, etc.). ) and climate change (such as hot and cold, etc.). ) can cause itching; Contact with dust, glass fiber and dust mites in daily work and life, eating some spicy food and wearing some close-fitting clothes will all cause itching all over the body. Systemic itching can also be caused by drugs, such as opium alkaloids, nicotinic acid, antidepressants, cimetidine and some central nervous system stimulants.
The cause of localized itching is sometimes the same as systemic itching. For example, diabetes can cause generalized itching and localized itching. Anal pruritus is mostly related to pinworm disease, prostatitis, hemorrhoids and anal fistula, scrotal itching is often related to local hyperhidrosis, friction and tinea cruris, and vulvar itching is mostly related to leucorrhea, vaginal trichomoniasis, vaginal mycosis, gonorrhea, diabetes and cervical cancer, and may also be related.
【 Clinical manifestations 】 According to the scope of itching, the disease can be divided into systemic and localized.
1. Patients with systemic itching have paroxysmal itching all over the body and often move from one place to another. The degree of itching is different, some itching can be tolerated, and some itching consciously. It is necessary to scrub and iron the skin with an iron brush or hot water until the skin bleeds and feels pain and burning, and the itching is temporarily relieved; It often gets worse at night, which affects patients' sleep. Due to severe itching and constant scratching, secondary lesions such as scratches and scabs may appear on the whole body skin, and sometimes eczema-like changes, lichen-like changes or pigmentation may occur. Scratched skin is prone to secondary bacterial infection.
Systemic itching can be divided into:
(1) Senile pruritus: It is mostly induced by factors such as decreased sebaceous gland secretion, dry skin, degenerative atrophy, etc., and it is more common in trunk.
(2) Winter itching: induced by cold, often accompanied by dry skin, aggravated when undressing and sleeping.
(3) Summer itching: high fever and humidity are often the inducement, and sweating often aggravates itching.
2. localized itching refers to itching that occurs in a certain part of the body and is common in clinic:
(1) anal pruritus: the most common. Both men and women can get sick, mostly in middle-aged men, and children are more common in pinworm patients. Itching is often confined around the anus, sometimes spreading forward to the scrotum and backward to both sides of the gluteal groove. The skin around the anus is often grayish white or pale white, and the anal folds are thick, resulting in radial chapping due to scratching; Sometimes secondary infection occurs; After a long time, the skin around the anus becomes thicker and covered with moss, and pigmentation will also occur.
(2) Vulvar pruritus: mainly occurs in labia majora and labia minora, and the pubic mound and clitoris can also occur. Due to itching, the vulva skin is often scratched and grayish white, and the clitoris and vaginal mucosa can be red, swollen and eroded.
(3) Scrotal itching: Itching occurs in scrotum, but it can also spread to penis or anus. Due to constant scratching, scrotal skin is thickened, pigmented and lichenoid, and some patients can see erosion, exudation, scabbing and eczema-like changes.
(4) Others: such as head itching, leg itching, palmoplantar itching, etc. In addition, there is hereditary localized itching, which is more common in women aged 20 ~ 30.
[Diagnosis and differential diagnosis] According to the fact that there is no primary skin lesion, there is only itching, which is easy to diagnose. In order to find the pathogenic factors, a comprehensive physical examination and laboratory examination are often needed.
Once secondary skin lesions appear, they should be differentiated from the following diseases according to their medical history:
(1) Urticaria: There are specific lesions (wheal) and course evolution.
(2) Insect bite: Typical lesions are wheal-like papules with small blisters at the top, and most of them have no systemic symptoms.
(3) Drug eruption: there are certain drug addicts with a certain incubation period. Sudden skin lesions, except fixed drug eruption, are symmetrically distributed.
(4) Scabies: there is a history of contact infection, prone parts and typical skin lesions. If we can find the scabies, we can make a diagnosis.
[Treatment] Try to find out the reason and cure it.
1. Pay attention to skin hygiene in general treatment and strive for regularity in life. Avoid scratching, scalding with hot water, drinking, drinking strong tea and eating spicy food. Patients with systemic diseases should actively treat the primary disease; For patients with neurasthenia, sedatives and hypnotics can be appropriately selected.
2. Systematic therapy
(1) antihistamines: As first-line drugs, various H 1 receptor antagonists can be selected, and H2 receptor antagonists can also be used in combination; Calcium and vitamin C can enhance the efficacy of antihistamines.
(2) Venous occlusion of procaine hydrochloride: procaine 4 mg/(kg d) dissolved in physiological saline for 500mI, 10 day as a course of treatment; In severe cases, intravenous lidocaine is effective, but this effect lasts for a short time (only a few hours) and can cause hypotension. Long-term use of procaine hydrochloride and lidocaine should pay attention to the possibility of contact allergy.
(3) Sex hormones: commonly used in elderly patients. Male patients are given testosterone propionate 25mg/d by intramuscular injection twice a week or methyltestosterone 5mg/d by oral administration; Female patients can take diethylstilbestrol 1 mg/d twice orally or inject progesterone 10 mg/d intramuscularly. Patients with reproductive system tumors or hepatic and renal insufficiency should avoid hard or cautious use.
(4) Others: injection of naloxone is effective in patients with cholestasis, and amitriptyline can be used when it is ineffective.
3. Local treatment
(1) External drugs: such as phenol calamine lotion, glucocorticoid ointment or cream; Patients with vulvar pruritus or anal pruritus should avoid using irritating drugs.
(2) Local blocking therapy: Diphenhydramine 25mg and procaine were injected subcutaneously at the focus, every other day 1 time; Triamcinolone acetonide or dexamethasone plus procaine can also be used to block the skin lesions subcutaneously, once a week 1-2 times.
(3) Physical therapy: ultraviolet irradiation, subcutaneous oxygen delivery, starch bath, bran bath or mineral spring bath are feasible for itching all over the body; When local itching is ineffective after repeated treatments, isotope deficiency or shallow X-ray treatment can be considered.
Experts interpret skin itching in autumn and winter.
It's late autumn. With the climate change in the north, people's skin becomes dry, and the number of patients suffering from skin pruritus increases, most of whom are middle-aged and elderly people. Many people feel itchy for unknown reasons, and the more they scratch, the more itchy they get. Some people scratch their skin, but they still don't solve the problem, which is very annoying. In this regard, we specially invite experts to interpret skin itching.
Interviewee: Li Qing, member of the Expert Committee of Dermatology and Venereology of Beijing Medical Doctor Association, member of the Department of Dermatology and Venereology of Capital Medical University, and deputy chief physician of dermatology of Beijing Tiantan Hospital.
Interviewer: Zhu Lili
■ Why does the skin itch after autumn?
Interviewer: Every autumn and winter, my father always feels itchy, especially afraid of taking a bath, because every time I take a shower, I feel itchy all over, and my skin is itchy when I scratch it. Why?
Li Qing: If your father has no other systemic diseases, he may have itchy skin.
Skin covers the surface of human body and is the natural coat of human body. The outermost layer of skin is stratum corneum, and there is a layer of sebum film on stratum corneum, which plays an important role in the integrity of skin barrier function. Sebum membrane is a translucent milky membrane formed by emulsification of sebum, sweat and epidermal cell secretions. Free fatty acids, lactate, urea and uric acid in sebum membrane are natural moisturizing factors, which can moisturize the skin. The stratum corneum and sebum membrane can prevent the loss of skin moisture.
In autumn and winter, the sebum and sweat secreted by human sebaceous glands and sweat glands decrease, and the sebum membrane decreases obviously. The sebaceous glands and sweat glands of the elderly shrink, and the skin becomes thinner and drier, which is more prominent. The sebum membrane of people who often take a bath is thin, and the integrity of the stratum corneum of people who have the habit of taking a bath is destroyed. Old people and people who often bathe in autumn and winter have dry skin and are prone to chapped and itchy skin. Scratching will damage the epidermis and aggravate itching.
Clinical manifestations of skin itching
Interviewer: Which parts of the skin itch easily?
Li Qing: Skin itching is mainly manifested as itching on skin that looks normal. It can be general itching or local itching of the whole body skin, and its position is not fixed, but it is more common in calves, forearms, back and waist and abdomen. It can also be aggravated by emotional excitement, temperature changes, drinking or eating spicy food.
Interviewer: What kinds of itching are there?
Li Qing: Itching can be divided into persistent or paroxysmal, with different degrees. Generally, it is heavier at night, and mild itching can be tolerated. In severe cases, the itching is unbearable. Once it happens, it is difficult to stop, and it is often difficult to fall asleep through severe scratching. The duration of itching varies from several hours to several minutes. Because of itching, repeated scratching for a long time can cause scratches, scabs, chapped skin, pigmentation and even moss-like or eczema-like changes, resulting in thickening and roughness of the skin, and even secondary skin infection after scratching. Local itching often occurs in a certain part of the body. Such as anal pruritus, scrotal pruritus, vulvar pruritus and scalp pruritus.
■ methods for preventing skin itching and skin care
Interviewer: What causes itchy skin?
Li Qing: Many internal and external factors can cause itching. Common ones are: environmental factors (season, temperature, humidity, etc. ), living habits (such as bathing habits, soap, cleaning skin care products, wearing clothes, etc. ), individual skin characteristics (such as aging, dryness, etc. ), neuropsychiatric factors (such as emotional tension, anxiety, excitement, depression, etc. ), as well as systemic diseases (such as liver and kidney diseases), but the most common cause of skin itching is improper nursing.
Interviewer: How to care for skin to prevent skin itching?