Pediatric drug-induced dermatitis

Introduction to pediatric drug dermatitis Dermatitis medicinal dermatitis (dermatitis medicinal rash) is also called drug rupture (drugruption), which refers to the skin or mucous membrane reaction caused by drugs entering the body through various routes (such as internal administration, injection, inhalation or stuffing). Severe cases may be associated with systemic damage, may be accompanied by visceral damage, or even death. Drug eruptions can be caused by allergies and non-allergic reactions. The latter refers to pharmacological predictability, often related to dose, while the former is not related to pharmacological effects, and is found in a small number of individuals, which occurs through an allergic reaction mechanism. The former type of drug eruption discussed in this article mainly refers to those caused by drug allergy, but the rash caused by the local action of the drug itself, such as the erythema reaction of amyl nitrite, is not included in the scope of this article. basic knowledge The proportion of sickness: 0.01% Susceptible people: children Mode of infection: non-infectious Complications: sepsis erythroderma anaphylactic shock

Pediatric drug dermatitis etiology

(1) Causes of the disease

The external factors of drugs include impurities in drugs, dosage, type, route of administration, accumulation and antigenicity, and many other factors related to drug eruption. However, the antigenicity of drugs is the most important cause of drug eruption. Drug-induced dermatitis refers to the inflammatory reaction of the skin mucosa after the drug enters the body by internal administration, injection or other means. The drug allergy refers to the allergic reaction caused by the drug as an allergen. The drug is an external cause of drug eruption. It goes without saying that most of the drugs are small molecule chemicals, which can only be regarded as haptens. They must be combined with proteins in the body to become whole antigens, and the drugs are antigenic.

There are four main types of drugs that often cause drug dermatitis:

1. Antipyretic and analgesic drugs, among which pyrazolone and salicylic acid are the most common, such as aspirin, soami pain tablets, analgin.

2. Sulfonamides are mostly caused by SMZco.

3. Antibiotics are most caused by penicillin, especially ampicillin.

4. Sedative and anti-epileptic such as barbital, phenytoin.

Other drugs such as furazolidone (), serum products, and drug allergies caused by traditional Chinese medicine in recent years have also received increasing attention.

(two) pathogenesis

Its mechanism is the same as allergic reaction. Some drugs are complete antigens, such as tetanus antitoxin, Baibai broken vaccine, etc. Most drugs are non-protein, called haptens, when they invade human and body tissue proteins (also known as carrier proteins). The covalent bond is an irreversible and stable hapten-protein complex, which becomes a complete antigen, which can stimulate the body to produce specific antibodies. These antigenic antibodies produce allergic reactions on the skin and mucous membranes, which causes drug-induced dermatitis. A rash can occur even in very small amounts for every same drug.

The manifestation of drug-induced allergic reaction is not related to the pharmacological action of the drug. It is not related to the dose and toxicity. The incidence is limited to a small number of sensitized people, and there is a certain incubation period. Take the skin rash type as an example. After the first dose, after the drug is used, The sensitization period of 4 to 20 days (average of 8 to 10 days) is in a state of potential allergic, asymptomatic. If the drug continues to be administered, it will be an allergic reaction after 4 to 5 days. If the drug has changed in the past, the body has changed. Should be in the state, re-medication, within 24h of the reaction, some individuals can tolerate a drug for several months to several years, once the body changes, the reaction can occur within a few minutes to 24h, occurred In some allergic reactions, there may be cross-allergy to drugs or their metabolites that are similar in chemical structure, and polyvalent allergies may occur, that is, in the extreme phase of drug dermatitis, for some structurally different drugs, Allergies should be noted in medications.

Non-allergic mechanisms can also trigger drug dermatitis, which refers to the intrinsic pharmacology of drugs, intolerance of toxicity, and so on.

After the patient's skin is exposed to certain substances (including drugs), a rash occurs due to the specific sensitivity of the epidermis, which is called contact dermatitis.

Pediatric drug dermatitis prevention

Strictly grasp the indications, side effects, correct use of drugs, avoid allergic reactions, carefully ask about the history of drug allergy, and avoid using sensitizing drugs again.

Pediatric drug dermatitis complications Complications sepsis erythrodermic anaphylactic shock

Complications of liver toxicity, nephrotoxicity, sepsis, pneumonia complicated with heart failure, erythroderma, hypertension, suppurative tonsillitis, anaphylactic shock, etc., the following three types of clinically occurring:

1. Septicemia: It often occurs in severe cases that are extremely serious and have not been treated in time. As pathogens invade the blood circulation, they rapidly grow and multiply within them. It is a serious infection when the patient's general condition is poor and the pathogenic bacteria are virulence and quantity.

2. erythroderma: also known as exfoliative dermatitis, clinical manifestations of flushing, desquamation, involving the whole body or most of the skin surface. The disease is currently considered to be a response to some skin diseases or drugs, or may be complicated by leukemia, lymphoma or visceral malignancy.

3. Anaphylactic shock: A strong systemic allergic reaction caused by the body's allergy to drugs or certain biological products. The most common is anaphylactic shock caused by injection of penicillin. The clinical features are short-term rash, laryngeal edema, decreased blood pressure, and difficulty breathing.

Pediatric drug-induced dermatitis symptoms Common symptoms scaly scarlet fever-like skin rash fever accompanied by rash wind group hypothermia glottic edema nodular exfoliative dermatitis maculopapular rash like urticaria...

The clinical phenomenon of drug dermatitis is intricate. On the one hand, different drugs can cause the same rash; on the other hand, a drug can cause a variety of rashes.

1. Different types of drug eruptions

(1) fixed drug eruption: common in the country, refers to the same form of drug dermatitis repeated in the same part, is more common in drug eruptions, typical lesions are round or oval edematous purple red spots, the edge is clear, There may be small blisters on it, such as in the mouth or external genital area, which is characterized by erosion and erythema. Each time it occurs in the original part and gradually enlarges, new skin lesions may occur in other parts, and pigmentation may remain after disappearing, such as taking medicine again. When the pigment spots are obviously red, occasionally patients with extensive skin lesions may be accompanied by fever, vomiting, loss of appetite and other systemic symptoms, often by sulfa drugs, barbiturates, pyrazolone, antipyretic and analgesic drugs, phenolphthalein and antibiotics. Tetracycline, penicillin, quinine and other drugs.

(2) urticaria type drug eruption: refers to urticaria caused by drugs, the typical skin lesions are unequal wheals, often spread from the head and face to the body, may be accompanied by low fever, abdominal pain, chest tightness, etc., some may be associated with blood vessels Neuropathic edema, often caused by penicillin, furazolidone (cyclidine), streptomycin, tetracycline, sulfonamides, vaccines, enzymes, insulin, etc., tetanus antitoxin can cause delayed urticaria, about 7 days after injection It happened.

(3) Measles-like erythema: for scattered or dense red maculopapular rash, or cap needle to rice-sized papules, trunk, and limb rash.

(4) Scarlet fever-like erythema: flaky erythema of different sizes from the beginning, from the head, rapid fusion, development to the trunk, limbs, intense itching, after 1 to 3 weeks, sputum or flaky scales, often by Sulfonamides, streptomycin, barbital, penicillin, streptomycin, antipyretic analgesics, pyrazolones, phenylbutazone, p-aminosalicylic acid, griseofulvin, etc.

(5) rare types are: pityriasis-like rose, acne-like, lichen-like drug dermatitis, hair loss, pigmentation, purpura or eczema-like drug dermatitis, hospitalized pediatric drug eruption is the most common form of urticaria, followed by measles Or scarlet fever like rash type drug eruption, severe drug rash ranked in the third place, followed by polymorphic erythema type, fixed erythema type and purpura type, sensitizing drugs are most common with antibiotics, followed by antipyretic analgesics, sulfa drugs , preventive injections and anti-epileptic drugs.

2. Drug and rash types

A typical rash of various drugs is described below:

(1) Penicillin: anaphylactic shock, urticaria, angioedema, measles-like, scarlet fever-like rash.

(2) Streptomycin: fixed drugs, erythema multiforme, exfoliative dermatitis, maculopapular rash and nodular erythema.

3) Sulfonamide: fixed drug, erythema multiforme, exfoliative dermatitis, maculopapular rash and nodular erythema.

(4) Aspirin: fixed drugs, erythema multiforme, exfoliative dermatitis, maculopapular rash and nodular erythema.

(5) Furazolidone (Metring): a fixed drug, a measles-like scarlet fever rash, a bullous epidermis release, a urticaria-like, nodular erythema, exfoliative epidermitis, purpura.

(6) belladonna and atropine: fixed drug eruption, urticaria, angioedema, polymorphous erythema, purpura.

(7) phenobarbital chloramphenicol: urticaria multi-annular intermediate skin is hairy, edema of the eyelids, or red papules, red hot rash and purpura involving the palm and sole.

(8) phenacetin: fixed drug eruption, scarlet fever rash, measles-like, erythematous erythema, eczema-like, bullous epidermis release.

(9) procaine: anal itching, angioedema.

(10) Arsenic: fixed drug eruption, urticaria, erythema multiforme, angioedema.

(11) : polymorphous erythema, urticaria, itching.

(12) Bromine: erythema, coloring, keratinization, herpes zoster, herpes, pustules, ulcers, urticaria, exfoliative dermatitis, may be caused by glottic edema or exfoliative dermatitis.

(13) chloral hydrate: gingival coloration, stomatitis, erythroderma, scarlet fever rash, erythema, urticaria and itching.

(14) Digitalis: Acne-like, nodular, proliferative, a small number of bullae.

(15) Ephedrine: erythema, a small number of urticaria, papules, blisters and purpura.

(16) Iodine: Scarlet fever rash, erythema and papules.

(17) Mercury: Scarlet fever rash, erythema, eczema-like rash, purpura.

(18) Opium: acne-like, nodules, blisters.

(19) Phenol: gingival coloration, stomatitis, scarlet fever or eczema-like rash.

(20) quinine: erythema, urticaria; salicylic acid: fixed erythema, occasionally exudative.

(21) Shi Ning: erythema, scarlet fever like rash.

(22) Serum (including diphtheria and tetanus antitoxin): erythema, urticaria, occasionally measles-like, rubella-like or scarlet fever-like rash.

(23) Immunosuppressive agents: hair loss, stomatitis, pigmentation of the skin nails.

Pediatric drug dermatitis examination

1. Blood routine: Eosinophilic basophils may be elevated.

2. Intradermal test: The resulting sensitizing drug is formulated into a concentration, and 0.1 ml of intradermal injection is performed in the forearm for observation. If a wheal is present, the infiltrating nodule is extremely positive.

3. Passive transfer test: 1-2 ml of blood was taken from the patient to be examined, serum was prepared, 0.1 ml of normal human forearm was aspirated with a syringe, and 24 hours later, suspicious drugs were injected into the sensitive area to observe the local reaction. Usually after 5-30 minutes. If local erythema appears, the wind group is positive. Partial erythema and wheal are positive after several minutes to several hours after oral administration. In this way, look for drugs for allergens.

4. Alkali signal degranulation test.

Diagnosis and diagnosis of pediatric drug dermatitis

diagnosis

Drug-induced dermatitis is similar to skin symptoms of many diseases in childhood, such as measles, scarlet fever, purpura, rubella, polymorphous erythema, etc. For plaques of unknown cause, it is often necessary to consider the possibility of drug-induced dermatitis. It is necessary to accurately understand the history of medication, latency and rash. The development process, otherwise difficult to diagnose, based on medication history, incubation period, clinical manifestations and development process for comprehensive analysis, if necessary, through objective experimental methods to determine the type of sensitizing drugs, often using skin scratches and intradermal injection experiments , patch test, before making a diagnosis.

Differential diagnosis

Asked about the history of medication is easy to distinguish from other causes of urticaria, herpes, eczema, scarlet fever.

(1) Urticaria: a common disease in the dermatology department, whose clinical manifestations are localized edema of the skin mucosa with varying degrees of edema, accompanied by severe itching. It has no peeling and pigmentation, skin scratch test. Positive does not have a history of medication, so as to distinguish.

(2) Eczema: It is a common allergic skin disease with obvious tendency of exudation, accompanied by severe itching, slow course of disease and easy recurrence. It occurs in summer, no history of medication, no history of medication, easy to distinguish .

(3) Scarlet fever: It is a pediatric acute respiratory infection caused by group A hemolytic streptococcus, which is caused by respiratory tract infection. It is also a common rash infection in pediatrics. The disease is clinically characterized by fever, angina, systemic scarlet fever rash and rash. It can be peeled or desquamated. It has the characteristics of Pap disease, pale ring and strawberry tongue. There is no history of medication. Use this to distinguish.

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