Dermatitis eczema is a common disease in dermatology, accounting for about 20-30% of dermatology outpatients. Its etiology is complex and the condition is prone to recurrence, and it belongs to one of the difficult diseases in dermatology.
First, let us understand the concept of eczema, which is currently considered to be a non-infectious inflammatory skin disorder of unknown etiology that may be caused by a variety of internal or external factors. It is only a morphologic descriptive name, not an etiologic diagnosis. Clinically, any rash with features such as erythema, papules, blisters, vesicles, oozing, desquamation, hypertrophy, and chapping, with significant itching, exudation and tendency to fuse, and unknown etiology, can first be proposed to be diagnosed as eczema. Eczema is a general term for a specific type of inflammatory skin disorder. Each clinical case of eczema may have a different etiology.
So what is the difference between eczema and dermatitis?
One viewpoint does not strictly distinguish between dermatitis and eczema, for example, some people refer to atopic dermatitis as atopic eczema and seborrheic dermatitis as seborrheic eczema, etc. Another viewpoint is that dermatitis refers to inflammation of the skin in general, such as contact sensitization, infection, etc., while eczema refers specifically to a non-infectious inflammatory condition. The third point of view will be the pathogenesis or clinical features are relatively clear called a certain dermatitis, where the etiology is temporarily unclear are generally diagnosed as eczema. The first is that the person who has been in contact with the outside world is called a dermatitis, and the second is that the person who has been in contact with the outside world is called a dermatitis. Eczema is a temporary concept, once the cause of eczema is clear, this eczema should be diagnosed as so-and-so dermatitis, and should no longer be diagnosed as eczema.
Classification of eczema
There are two main clinical categories, one is based on the stage of the lesions for classification, the eczema lesions into acute, subacute and chronic stage lesions. The corresponding clinical diagnosis is acute eczema, subacute eczema and chronic eczema. This classification focuses only on clinical manifestations and does not suggest etiology. The other is to classify eczema into various subtypes based on the site of onset and clinical characteristics.
Classification according to lesion staging
Dermatitis and eczema can usually be divided into three types of lesions: acute, subacute and chronic. The acute phase is characterized by erythema, edema, and may be accompanied by papules, blisters, or exudates. In the subacute phase, blistering and exudation decrease, and crusting and flaking occur. The chronic phase is characterized by hypertrophic leathery skin and may be accompanied by hyperpigmentation or hypopigmentation.
Classification according to clinical features
We have tried to classify eczema into two main categories, classified eczema and unclassified eczema. Any eczema with relatively specific clinical features that can be clinically diagnosed is called classified eczema, such as bruising eczema, seborrheic dermatitis, etc. For those who have the clinical features of eczema and cannot be further classified, the diagnosis is unclassified eczema. Diagnosis can be based on the location such as perianal eczema, calf eczema, scrotal eczema, external ear eczema, etc. Diagnosis can also be based on factors such as lesion classification stage or season.
Contact dermatitis
Contact dermatitis is an inflammatory skin reaction caused by skin contact with certain substances in the living or occupational environment. According to the pathogenesis is mainly divided into the following categories.
1, allergic contact dermatitis: contact dermatitis caused by sensitive individuals exposed to allergens, the mechanism is a delayed allergic reaction. Its onset is mainly due to skin contact with allergens, mostly 1-2 days after contact onset. Since the onset of the disease requires a sensitization process, initial exposure does not usually lead to the onset of the disease. Common contact allergens are p-phenylenediamine in hair dyes, fragrances in cosmetics, nickel in metal products, and neomycin in topical medications.
2, irritant dermatitis: is a contact dermatitis caused by external substances through non-immune mechanisms. It can be caused by direct damage to tissue cells due to contact with substances, such as acid or alkali chemical burns, also known as “primary irritation”. Long-term exposure to soap, laundry detergents and other detergents, as well as plant juices can cause chronic skin irritation.
3, phototoxicity and photomorphic reactions: skin local contact or systemic absorption of certain compounds, and then after sunlight exposure, in the irradiation site caused by the skin inflammatory reaction.
4, systemic contact dermatitis: it is contact sensitive individuals systemic reaction after the absorption of the corresponding allergens.
Clinical manifestations: allergic contact dermatitis mostly manifested as acute or subacute eczema dermatitis, lesions are clearly defined, consistent with the shape of the contact, if not timely removal of allergens, this lesion can be extended to the surrounding or other parts. Chronic contacts can cause changes such as hypertrophy, dryness and cracking of the skin. Irritant dermatitis can manifest as acute, subacute or chronic eczematous dermatitis.
Diagnosis: A clear diagnosis can often be made based on well-defined, oddly shaped lesions and by following the history of exposure. Some contact dermatitis, especially chronic contact dermatitis, is often atypical and difficult to distinguish from eczema and requires patch testing for a clear diagnosis.
Treatment: remove the cause, through a detailed history and physical examination can be presumed some common irritants or allergens. Choose antihistamines with sedative effect to control itching and help patients rest well for inflammation recovery. If there is no contraindication, corticosteroid treatment is available for severe symptoms. Antibiotics are used for secondary infections.
Topical treatment: Select appropriate drug formulations according to the principles of topical drug use. Acute erythematous papules can be treated with topical corticosteroid cream, those with blistering exudation can use 3% boric acid solution for cold wet compresses, those with reduced exudation and crusting can use 25%-40% zinc oxide oil, those with chronic hypertrophy can use topical medium or strong corticosteroid ointment and hard cream, etc.
Prevention: It is important to have an awareness of common contact pathogenic factors, raise awareness of protection, and avoid exposure to strong allergens and irritants. Protective measures should be in place when these items must be used. Avoiding topical application of drugs that are easily exposed to sensitization, such as topical neomycin and topical antihistamines, can reduce the occurrence of systemic contact dermatitis.
Seborrheic dermatitis
The etiology of seborrheic dermatitis is unclear. It is mainly seen on the scalp, face, and diaper area of infants, and in adults it is mainly at the site of seborrhea. However, there is no direct relationship with the amount of sebaceous gland secretion. It is now mostly believed that oval-shaped Sporotrichia furfuracea infection is associated with seborrheic dermatitis. This bacterium is a putrefactive microorganism that is parasitic on the body surface of normal adults and is not seen in healthy children. Clinically, the use of topical ketoconazole for the treatment of seborrheic dermatitis is effective, so it supports the association of oval spores of furfur infection with this disease. Also emotional stress can trigger or exacerbate seborrheic dermatitis. The relationship between diet and seborrheic dermatitis is unclear.
Clinical manifestations: There are infantile and adult forms.
The infantile type occurs 3 to 4 weeks after birth and presents with erythema and greasy scales on the scalp, face, including the arch of the eyebrows, cheeks, trunk, diaper area, and axillae, and tends to form yellowish scabs. Pruritus is not obvious. It is self-limiting.
In adults, seborrheic dermatitis mainly affects the scalp and the anterior chest area, axillae, inframammary area, and groin. Seborrheic dermatitis of the scalp is divided into two types: inflammatory and non-inflammatory. Inflammatory cases show typical erythema and greasy flaking. It often extends to the hairline and behind the ears. There is mild pruritus. The non-inflammatory ones show light and heavy bran-like flaking, which is commonly known as dandruff, also known as dry pityriasis, and it has no obvious inflammatory damage. Facial seborrheic dermatitis mainly involves the arch of the eyebrow, the eyelid margin, the nasolabial folds and the beard area, showing erythema and greasy scales.
Diagnosis and differential diagnosis: The diagnosis is mainly based on clinical manifestations. It should be differentiated from atopic dermatitis, tinea capitis, psoriasis, interscalene rash, contact dermatitis, and other skin diseases. Infantile seborrheic dermatitis is generally self-limiting, with mild itching and quick response to treatment, whereas atopic dermatitis is difficult to treat and has a chronic recurrent course.
Scalp psoriasis: mostly red patches with clear borders and thick silvery-white scales, which are easier to identify if typical psoriasis damage is found in other parts of the body.
Contact dermatitis: the site of onset is not related to the site of seborrhea, the rash has clear borders, and there is a history of contact.
Intertriginous eruptions (folds) occurring in the periumbilical or perineal skin folds are easily confused with seborrheic dermatitis, but other seborrheic sites without seborrheic dermatitis damage can be differentiated.
Treatment: Infant scalp seborrheic dermatitis can be treated with baby shampoo to wash away the scabs, followed by emollient oil. Adults can first use a shampoo containing tar or ketoconazole to shampoo their hair twice a week, or once a day if the results are not good. If the effect is still not good, topical corticosteroid solution or ketoconazole cream can be used. The disease is prone to recurrence.
Other areas of seborrheic dermatitis can be treated with low potency corticosteroids for intermittent topical use, but be careful not to use them around the eyes. Creams containing ketoconazole may also be used. After the rash is controlled, only topical ketoconazole-containing creams may be used.
Seborrheic eczema
This condition is very common in clinical practice and is associated with a decrease in oil on the skin surface. It is commonly seen in patients with ichthyosis or in the elderly. Excessive bathing, the use of strong alkaline soaps, facial cleansers, or bathing water that is too hot can cause artificial skin defatting. Caused by the reduced function of sebaceous glands, the onset is mostly slow. Generally, in people over 50 years old, itching often occurs after bathing and gradually worsens with age. Those caused by excessive washing or the use of degreasing agents often have an acute onset, and it is actually an irritant contact dermatitis. It can also be seen in patients with tumors, people who use diuretics or histamine blockers, and people with HIV infection. The disease is most often seen in winter and is prone to develop in the elderly and those who take baths excessively, with the extensor side of the calf and the hands being the preferred sites.
Treatment: First remove the cause of the disease. Use some emollients to treat. For example, white petroleum jelly, vitamin E cream, mineral oil, etc. Available 1 to 2 times a day. Use emollient oils immediately after bathing to retain the moisture in the skin from evaporating. Topical corticosteroid preparations are best avoided because the skin barrier function has been significantly disrupted.
Coin-shaped eczema
Coin-shaped eczema is also known as discoid eczema. The etiology is unknown and the detection rate of bacteria on the lesions is high, but the relationship to bacterial infection is unclear. Patients are generally in relatively good health.
Clinical manifestations: The lesions of coin-shaped eczema tend to occur on the lower extremities, and the self-conscious symptom is itching. The lesions are coin-sized eczema-like damage with yellow ooze or yellow crust. It can be acute, subacute or chronic. The lesions can be single or multiple, with a tendency to be symmetrical. They may fuse into large areas. The disease is often prone to recurrence. There are no specific findings in routine laboratory tests.
Diagnosis: It is mainly based on typical clinical manifestations. The disease needs to be differentiated from tinea corporis, which is mostly dry and non-exudative, with peripheral expansion and central receding, and fungal microscopy can detect fungi.
Treatment: Topical corticosteroid preparations and antibacterial drugs can clear most lesions. Internal medication is generally not necessary.
Eczema of the hands
Hand eczema is very common and most have a chronic course. The incidence is high. The incidence is higher among nurses in the occupational population and may be related to factors such as repeated hand washing and exposure to medications. A significant proportion of hand dermatitis may eventually be identified as contact dermatitis. Some may be related to dust drift and ingestion of certain things. Most are difficult to treat because it is difficult to completely avoid these environmental factors. Some patients have difficulty finding the cause.
Clinical manifestations: Self-perceived symptoms are mainly pruritus, but there can be tingling or burning sensations. Other perceived symptoms can be classified into several types according to the mechanism.
Skin irritation: mainly acute or chronic irritation resulting in irritant dermatitis. The chronic ones are mostly seen in young and middle-aged women, especially housewives, so they are also called housewife dermatitis. Characterized by dry erythema, cracking and flaking, generally not seen edema and blisters.
Allergic contact dermatitis: The onset of the disease can be acute or slow. Acute cases have a clear history of exposure. The rash is mostly seen on the skin of the back of the hands. For example, contact dermatitis caused by wearing latex gloves in latex allergic individuals. Pruritus is evident, with erythema, papules, blisters and oozing at the site of contact. Chronic patients have an unclear exposure history and it is difficult to find the cause. For example, chronic erythematous hypertrophy of the hands due to allergy to nickel in labor tools has been reported.
Keratotic hypertrophic eczema: It can occur on the palm or dorsal side of the hand and presents as a limited patchy hypertrophic plaque, which may be accompanied by chapping or mild desquamation, mostly without exudation, and the etiology is mostly unidentified at present.
Diagnosis: It is easy to diagnose based on the history and clinical manifestations. The difficulty lies in finding the cause of the disease. Careful history taking and patch test can help to diagnose the cause.
Differential diagnosis: This disease needs to be differentiated from tinea cruris and exfoliative keratolytic disease.
Tinea capitis
It occurs mostly on the palms of one hand or in a typical bipedal one-handed pattern. The rash usually starts from the skin between the fingers, especially at the tiger’s mouth, and gradually expands. The lesions appear dry, rough and flaky. Fungi can be detected by fungal microscopy or culture. Hand dermatitis mostly occurs bilaterally, with indistinct rash borders, mild to severe lesions, and acute episodes where no fungus can be detected locally.
Exfoliative keratolytic disease: Mostly seen in children and adolescents. It is a symmetrical patchy repeated peeling of the palmoplantar area, leaving a red base, without inflammation and itching, often accompanied by sweaty hands and feet.
Treatment: Same as contact dermatitis. Hypertrophic chapped lesions can be treated with keratolytic agents, such as 20% urea cream, to make the skin thinner before applying corticosteroids. Some stubborn cases can be tried PUVA treatment. Attention should be paid to removing the cause and aggravating factors and to skin protection.
Prevention
Skin protection: This includes not using too strong alkaline soap when washing hands and not using non-skin cleansers. Do not wash your hands too many times a day. Dry hands immediately after washing and use hand rubs or silicone creams. Wear gloves when in contact with irritants or allergens.