Symptom >> Dermatology >> Dermatology

Wheal-like lesions at the skin line

Introduction
Cause
Examine
Diagnosis

Introduction

Introduction Use a cotton swab (or pencil tip) to scribe on the patient's back skin. Use force to avoid scratching the skin. 1 to 3 minutes after the stroke, the wind-like lesions consistent with the scratches were found at the scribe line, and the diameter was 3 to 5 mm for 10 to 60 minutes. The patient felt itching, which was positive for the skin scratch marks.

Cause

Cause

Due to the allergic reaction of the skin after physical stimulation, the mast cells release the bioactive substances of histamine, causing the skin to expand and expand the permeability, so that the plasma and tissue fluid penetrate into the dermis.

Examine

an examination

Related inspection

Radioallergen Adsorption Test (RAST) Blood Routine

Skin scratch marks, also known as artificial measles, are allergic reactions to skin blood vessels, and the formation of allergic reactions is caused by internal and external factors. There is a special protein in the serum of such patients, which is immunoglobulin IgE. When such proteins are combined with allergens, the body will cause a series of reactions, and finally the mast cells around the blood vessels of the skin will release a large amount of histamine. , histamine causes skin vasodilation, and serum oozes out of the blood vessels, causing itching. At this time, the skin scratch test is positive.

The most common allergens causing skin scratch marks are drugs, especially penicillins, serum preparations, as well as bacteria, fungi, plant proteins, animal proteins, and the like.

Diagnosis

Differential diagnosis

There are two types of skin scratches:

A kind of simple skin scratch marks, more common in women, is a physiological abnormal reaction. The symptom is a piece of rubella that appears after the skin has been scratched by nails or other blunt objects, and is often accompanied by itching or other discomfort.

Another type of skin scratch is called a symptomatic skin scratch, which is common in young people with allergies. The cause of this is due to the abnormal reaction of the skin after physical stimulation, which causes the mast cells to release the bioactive substances of histamine, causing the skin to expand and expand the permeability, so that the plasma and tissue fluid penetrate into the dermis. . People with this kind of skin scratches often feel itchy skin for no reason, but unlike the common urticaria, the whole body has a rash, but when the skin is scratched with nails or other blunt objects, the skin appears first. The erythema of the road, then the edema of the wheal is higher than the skin, and the blush appears on the edge of the erythema, which is shaped like the traces left by the skin after being beaten by the skin whip. Some patients with severe symptoms may experience swelling of the lips even after the lips are bitten by the teeth.