Itching

Introduction The release of histamine from the affected area can promote itching. Scratching has an itching effect due to tenderness, but promotes the release of more histamine, aggravates the itching sensation, and forms a itch-gravity cycle that leads to more severe skin damage and inflammation. No special itch receptors have been found in histology. It is generally believed that itch is closely related to pain sensation, which may be transmitted through free nerve endings or peripheral nerve networks around the hair follicles. Some scholars believe that itch is mainly transmitted by the sensory organs at the junction of the epidermis and the dermis and the superficial skin plexus. The mechanism of itch is very complicated, and most skins are accompanied by varying degrees of itching.

Cause

The cause of the disease is complicated. Experiments have shown that the dog's skin has a susceptive receptor and is transmitted to the brain through the nerve endings. The release of histamine from the affected area can promote itching. Itching has an itching effect due to tenderness, but it also promotes the release of more histamine, aggravates the itching sensation, and forms a itch-gravity cycle that leads to more serious skin damage and inflammation. No special itch receptors have been found in histology. It is generally believed that itch is closely related to pain sensation, which may be transmitted through free nerve endings or peripheral nerve networks around the hair follicles. Some scholars believe that itch is mainly transmitted by the sensory organs at the junction of the epidermis and the dermis and the superficial skin plexus. The mechanism of itch is very complicated, and most skins are accompanied by varying degrees of itching.

an examination

Related inspection

Skin color skin elasticity check physical examination of skin diseases

According to the scope of itching, the disease is divided into two types: systemic and local.

1. Patients with systemic scrapie have paroxysmal itching throughout the body and often move from one place to another. The degree of itching is not the same, some itching can be tolerated, and some consciously itchy, need to use iron brush to brush the skin or hot water to wash, until the skin bleeding and feel pain and burning, the itch is temporarily relieved; often intensified at night , affecting the patient's sleep. Due to intense itching, the skin can be scratched, blood stasis and other secondary skin lesions, sometimes with eczema-like changes, mossy changes or pigmentation, scratching the skin is prone to secondary bacterial infection. Systemic scrapie can be further divided into:

(1) pruritus susilis (pruritus senilis): mostly due to sebaceous gland secretion function decline, skin dryness and degenerative atrophy and other factors induced, the trunk is more common.

(2) Winter scrapie (pruritus hiemalis): induced by cold, often accompanied by dry skin, undressing and sleeping.

(3) summer scrapie (pruritus aestivalis): high heat, humidity is often the cause, sweating often makes itching.

2, localized scrapie, refers to itching occurs in a certain part of the body, clinically common:

(1) Anal scrapie: the most common. Both men and women can be ill, more common in middle-aged men, children are more common in mites. Itching is often confined around the anus, sometimes spreading forward to the scrotum, back to the sides of the gluteal groove. The skin around the anus is usually grayish white or pale white, and the anus is thick and wrinkled. Radial cleft palate occurs due to scratching; sometimes secondary infection occurs; the skin around the anus is thickened to become lichen, and hyperpigmentation may occur. .

(2) Female pruritus: mainly occurs in the labia majora, labia minora, pubic lice and clitoris. Because itching is often scratched, the vulva skin is thick, grayish white, and the clitoris and vaginal mucosa may appear red and swollen.

(3) scrotal scrapie: Itching occurs in the scrotum, but it can also affect the penis or anus. Due to constant scratching, the scrotal skin is hypertrophic, pigmented, and lichen-like, and some patients may see erosion, exudation, scarring, and eczema-like changes.

(4) Others: such as scrapie in the head, scrapie in the lower leg, and scrapie in the palm. In addition, there are hereditary localized scrapie, which is more common in women aged 20-30.

According to the absence of primary skin lesions, only itching is easy to diagnose. In order to find the cause of the disease, a full physical examination and laboratory examination are often required.

Differential diagnosis

Once secondary lesions occur, they need to be identified based on their history and the following diseases:

(1) Urticaria: specific skin lesions (wind group) and the course of disease progression.

(2) Insect bite: The typical skin lesion is a wheal-like papule with a small blister at the top and no systemic symptoms.

(3) drug eruption: there is a clear medication, there is a certain incubation period, skin lesions suddenly occur, in addition to the fixed drug eruption, more symmetric distribution.

(4) Hemorrhoids: There is a history of contact infection, good hair and typical skin lesions. If you can find sputum, you can confirm the diagnosis.

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