radiation dermatitis
Introduction
Introduction to radiation dermatitis Radiation dermatitis (adiodermatitis) is caused by mucosal inflammatory damage caused by various ionizing radiation including X-rays and radioisotopes. With the improvement of radiation awareness and protection methods, people's alertness to such diseases has been greatly improved, but with the increasing popularity of radiation for medical diagnosis and treatment, and the continuous development of the atomic energy industry, The opportunity for people to contact with radiation is increasing, so the disease has an increasing trend. basic knowledge The proportion of illness: 0.025% Susceptible people: no special people Mode of infection: non-infectious Complications: fibrosarcoma
Cause
Causes of radiation dermatitis
(1) Causes of the disease
Radiation that can cause ionization of a substance is called ionizing radiation, including X-rays, gamma rays, boundary lines, electrons, protons, neutrons, etc. Ionizing radiation can cause reversible or irreversible damage to DNA of biological tissue cells, seriously interfering with metabolism. Even causing cell death, or causing DNA structural errors, causing mutations. In addition, it can also cause intramolecular ionization to cause secondary damage, such as ionization into hydroxyl groups, oxygen free radicals and peroxides, which can cause skin. Acute and chronic inflammation, ulceration, atrophy, pigmentation disorder or cancer formation, the incidence and severity of radiation dermatitis depends on the following factors:
1. There are differences in biological effects between different types of radiation.
2. The total dose of radiation and the dose of fractionated radiation, the incidence of skin cancer after irradiation requires at least 20cGy dose, the fractional irradiation method allows the skin to have enough time to recover, but the tumor tissue continues to destroy.
3. The radiosensitivity of the tissue increases as the degree of cell differentiation decreases.
4. The influence of biological factors, such as increased blood supply, increases sensitivity through oxidation, actinomycin D and metronidazole are radiosensitizers, and chloroquine and methoxalin (8-methoxy supplement) Osteolipin) has been shown to have protective effects in experimental studies.
(two) pathogenesis
Ionizing radiation can cause reversible or irreversible damage to the DNA of biological tissue cells, severely interfere with metabolism, or even cause cell death, or cause DNA structural errors, produce mutations, and, in addition, ionize the molecules in the tissue to cause secondary damage. Such as ionization into hydroxyl, oxygen free radicals and peroxides, these can cause acute and chronic inflammation of the skin, ulcers, atrophy, pigmentation disorders or cancer formation, etc., the incidence and severity of radiation dermatitis depends on: total radiation dose and The dose of secondary radiation, there are differences in biological effects between different types of radiation, and the radiosensitivity of tissues increases with the degree of cell differentiation, and the influence of biological factors.
Prevention
Radiation dermatitis prevention
Prevention of the occurrence of this disease should pay attention to:
1 Avoid excessive doses during radiotherapy.
2 Detailed observation of skin changes after radiotherapy, such as dermatitis has occurred, should be stopped, and regular follow-up observation.
3 Personnel engaged in radiation work should strictly abide by the operating procedures and strengthen protective measures.
4 regular physical examination, those who have a tendency to have lesions should rest in time, and those who are seriously ill should consider changing jobs. If a person who is engaged in X-ray work is found to have neoplasms in his hand, he should be closely followed up to prevent cancer.
Complication
Radiation dermatitis complications Complications fibrosarcoma
Acute radiation dermatitis is three degrees, and the chisel-like "radioactive ulcer" with sneak edge and dry base can last for several years and malignant.
Symptom
Symptoms of radiation skin inflammation Common symptoms Dry skin spotted pigmentation Deficiency scales Itching hair loss
Radiation has a certain incubation period for skin damage, short-term exposure to large doses of skin, short incubation period, usually several days after the onset of symptoms, manifested as acute radiation dermatitis, after a few years or decades of latent period, showing late damage, Long-term, low-dose radiation has a cumulative effect, and after years or decades, radiation dermatitis or even cancer can occur.
1. Acute radiation dermatitis is caused by receiving large doses of radiation in a short period of time and is generally divided into three degrees.
Once: The localized erythema with clear boundary, edema, accompanied by burning and itching, gradually subsided within 3 to 4 weeks, and there was scaling, residual pigmentation and temporary or permanent hair loss.
Second degree: the lesion is more obvious, in addition to erythema, edema, blistering, erosion or superficial ulcers, usually heal within 1 to 3 months, after the pigmentation, pigmentation, capillaries Expansion, skin atrophy, permanent hair loss, scar formation and sweat gland dysfunction.
Third degree: local redness and severeness, tissue necrosis soon, ulceration, lesions can extend to subcutaneous tissue, bone and viscera, chisel-like "radioactive ulcer" with sneak edge and dry base can last for several years and malignant transformation (Figure 1), this kind of ulcer can be accompanied by severe pain. If it is cured, it can form atrophic scar, and it can have secondary damage such as pigmentation, pigment loss, hair loss and telangiectasia.
2. Subacute radiation dermatitis In a few cases, scaly erythema occurs several weeks to several months after irradiation. The lesion is similar to once acute radiation dermatitis, but its histopathology indicates a cellular immune response, but not a direct toxic injury.
3. Chronic radiation dermatitis often occurs several years after irradiation, which may be the inevitable result of short-term large-scale irradiation treatment of skin malignant tumors. Other reasons include repeated sub-erythema zonal dose X-ray irradiation for hemorrhoids, repeated X-ray fluoroscopy, boundary line treatment , superficial and deep X-ray, radium and electron beam treatment, the total dose of different rays and irradiation determines the severity of the reaction, with local skin dryness and atrophy, gland dysfunction, hair loss, telangiectasia, pigmentation increase or decrease The nails are dark, brittle, longitudinally split, and fall off, and can form intractable ulcers or skin cancers for a long time.
4. X- ray erythema single-radiation amount super-domain value causes double-phase or three-phase erythema, superficial radiation often causes biphasic reaction, while deep penetrating radiation produces three-phase reaction, and fractional radiation can be significantly delayed And prolong the occurrence of radiation erythema, one-stage erythema begins to appear within a few minutes to 24 hours after X-ray irradiation for 2 to 3 days. Depending on the radiation dose, the second stage erythema can appear immediately after irradiation or 8 to 9 days after irradiation. Occurred, the erythema deepened and increased in the next 7-8 days, and the proteolytic enzyme released from the damaged epithelium may play a regulatory role in this period. This period is about 4 weeks after irradiation, and the pigmentation may increase, occasionally Three stages of erythema occur 6 to 7 weeks after irradiation for 2 to 3 weeks, and the coexisting increase in pigmentation makes it less noticeable.
Examine
Radioactive dermatitis examination
Histopathology:
1. Acute radiation dermatitis lesions involve the epidermis and dermis. In severe cases, the subcutaneous tissue may be involved. The epidermis has moderate to obvious intracellular and intercellular edema, basal cell pyknosis and liquefaction degeneration, mitosis is rare or absent, and the epidermis is flat or disappears. The dermis has obvious edema and diffuse distribution of various inflammatory cells, and the blood vessels are obviously dilated, and venous thrombosis and micro-bleeding are common.
2. Chronic radiation dermatitis epidermis atrophy and thinning, epidermal process disappears, superficial fibrosis of the dermis, large, shape-specific, sometimes multinucleated fibroblasts, superficial blood vessels wide, fibrous red dyed cellulose around the blood vessels Deposition, deep intimal thickening, basal cell liquefaction degeneration, visible melanocytes.
3. X-ray erythema histopathology shows that the upper vascular vasodilation with a certain degree of endothelial cell swelling and increased vascular permeability, can also occur mast cell degranulation and mild non-specific perivascular cell infiltration, lymphocytes and polymorphonuclear Cell-based, mitosis in the epidermis, hair and sebaceous gland can be inhibited at the beginning of erythema, while cell differentiation, keratinization and shedding are not affected by radiation, which leads to a certain degree of epidermal thinning, after irradiation 2 to 3 weeks, the melanin-filled chromophores increased significantly in the dermis, but with the increase in the number of melanocytes, and finally, the lesions subsided, the epithelium recovered, and other abnormal changes were reversed.
Diagnosis
Diagnosis and diagnosis of radiation dermatitis
The diagnosis can be determined based on medical history and clinical manifestations.
Chronic radiation ulcers must be differentiated from ulcerative cancer by biopsy.
