Definition: Superficial dermal and epidermal inflammation caused by a variety of internal and external factors.
Clinical features: often symmetrical distribution, the acute phase of the lesions are mainly papules, with a tendency to exude; the chronic phase is dominated by mossy changes, prone to recurrent attacks.
Etiology and pathogenesis
Complex interaction of various internal and external factors, possibly related to delayed (type IV) allergic reactions
May be related to the following factors
Internal factors
Chronic infectious lesions: chronic cholecystitis, tonsillitis, intestinal parasitosis, etc.
Endocrine and metabolic changes: menstrual disorders, pregnancy
Blood circulation disorders: varicose veins in the lower legs
Neuropsychiatric factors: such as mental stress, overwork, etc.
Genetic factors (allergic qualities): related to the susceptibility and tolerance of the individual.
External factors
Food: fish, shrimp, beef and mutton, etc.
Inhalants: pollen, dust mites, microorganisms, etc.
Living environment: such as sunlight, heat, dryness, etc.
Animal skin and fur
Various chemical substances: such as cosmetics, soap, synthetic fibers, etc. can induce and aggravate the disease.
External factors
Food: fish, shrimp, beef and mutton, etc.
Inhalants: pollen, dust mites, microorganisms, etc.
Living environment: such as sunlight, heat, dryness, etc.
Animal skin and fur
Various chemical substances: such as cosmetics, soap, synthetic fibers, etc. can induce and aggravate the disease.
Clinical manifestations
The course of the disease and clinical manifestations are divided into
Acute eczema
↑↓
subacute eczema
↑↓
Chronic eczema
Acute eczema
Prevalent sites: face, ears, hands, feet, forearms, exposed parts of the lower legs, or in severe cases, diffuse throughout the body, often symmetrically distributed.
Characteristics of lesions: polymorphic, with pinhead to corn-sized papules and papules on the basis of erythema, and in heavy cases, small blisters, fused into patches, with indistinct boundaries, punctate vesicles and oozing after scratching.
Self-perceived symptoms: intense itching, scratching, hot water can be aggravated. In case of secondary infection, pustules, pus and crusts are formed, and even systemic symptoms such as fever and enlarged lymph nodes appear. If herpes simplex virus infection is combined, herpes-like eczema may occur.
Subacute eczema
It develops due to improper treatment of acute eczema.
It is characterized by reduced redness and exudation, but there are still papules and a small amount of papules, dark red lesions, a little scaling and mild infiltration; it is still consciously and intensely pruritic.
Re-exposure to allergens, new stimuli or improper treatment can lead to acute flare-ups; if prolonged → chronic eczema.
Chronic eczema
Chronic eczema can be caused by acute eczema and subacute eczema, or it can be chronic from the beginning due to mild and continuous irritation.
It occurs on the hands, feet, calves, elbow fossa, femur, breast, vulva, anus, etc., and is mostly symmetrical in onset.
It is characterized by papules, scratches and scales on infiltrative dark red patches of the affected skin, local hypertrophy, roughness, mossy changes, hyperpigmentation or hypopigmentation. It is often paroxysmal, with marked pruritus. The disease may be mild or severe, and may last for months or longer.
Special types of eczema
Eczema of the vulva, scrotum, and anus Itching is intense, often due to excessive scratching, hot water, and redness, vesicles, and oozing, and may be chronic with long-term recurrent attacks and localized mossy skin.
Varicose eczema (depressed dermatitis) Mostly affects patients with venous hypertension in the lower extremities, especially in those with varicose veins in the lower extremities, accompanied by swelling of the lower legs and easily forming ulcers that do not heal easily.
Coin-shaped eczema occurs on the extremities. The lesions are dense small papules and papules, fused into round or round-like coin-shaped patches, with clear boundaries, 1~3 cm in diameter, flushing and oozing in the acute phase, hypertrophy and increased pigmentation in the chronic phase, dry and scaly surface, and intense itching.
Diagnosis and differential diagnosis
The diagnosis is not difficult based on features such as polymorphic, symmetrical lesions with a tendency to exude and intense pruritus in the acute phase and mossy lesions in the chronic phase.
Acute eczema should be differentiated from acute CD, chronic eczema should be differentiated from chronic simple moss, and hand and foot eczema should be differentiated from tinea cruris.
Treatment
Attention should be paid to avoiding various suspected causative factors, spicy and stimulating foods and alcohol, and excessive scalding.
Internal drug treatment
Antihistamines, sedatives and tranquilizers, and glucocorticoids are generally not recommended; in the acute stage, calcium, VitC, sodium thiosulfate, etc. can be injected or procaine can be closed intravenously; antibiotics should be added for secondary infection.
Topical drug treatment
The principles of topical medication should be fully followed:
In the acute stage, when there is no exudate or not much exudate, zinc oxide oil can be used, and in many cases 3% boric acid solution can be applied wet; after the exudate is reduced, glucocorticoid cream, which can be used alternately with oil.
In the subacute stage, glucocorticoid emulsions and pastes can be used, and antibiotics can be added to prevent and control secondary infections.
In the chronic stage, glucocorticoid creams, hard creams and coating agents can be used; in the stubborn limited lesions, glucocorticoids can be injected into the skin lesions.