Eczema


The terms eczema and dermatitis are used interchangeably, denoting a polymorphic inflammatory reaction that affects the epidermis and dermis. There are several causes and a wide variety of clinical manifestations. Acute eczema / dermatitis are characterized by pruritus, erythema, and vesicle formation; chronic eczema / dermatitis are characterized by pruritus, xerosis, lichenification, hyperkeratosis, desquamation, and fissures.

Classifications of dermatitis according to the state of the skin.

Acute:
Well-defined erythema and edema and superposition of very close papules or vesicles without umbilication (Figure 3-3); in severe reactions, blisters, confluent erosions that exude serum and scab formation. The same reactions can occur after several weeks in unexposed sites.

Subacute:
Plaques with mild erythema showing flaking with small, dry scales, sometimes associated with small, erythematous, punctate or rounded papules and flaking (Figures 3-4 ). Chronicles. Lichenification plates (thickening of the epidermis with deep skin lines in a parallel or rhomboidal pattern), desquamation with satellite papules, small, firm consistency, with flat or rounded upper edge, excoriations and pigmentation.

Distribution:
Initially, limited to the area of ​​contact with the allergen (eg, ear lobe [earrings], back of the feet [shoes], wrist (wristwatch), neck [collar use] and lips [pencil] labial]), often with linear distribution, with artificial patterns, contact with plants often results in linear lesions (eg, Rhus dermatitis), initially limited to the site of contact and later with extension of the lesion .

Extension:
Isolated lesions, localized to a region (eg, footwear dermatitis) or generalized (eg, plant contact dermatitis).

Allergens

TABLE 1. MAIN CONTENT ALLERGENS (CONTACT DERMATITIS IN THE UNITED STATES) AND OTHER COMMON CONTACT ALLERGENS

Contact dermatitis or contact eczema is a generic term applied to acute or chronic inflammatory reactions by substances that come into contact with the skin.

Irritant contact dermatitis (ICD) is caused by chemical irritants.

Allergic contact dermatitis (ACD) is caused by an antigen (allergen) that triggers a type IV hypersensitivity reaction (cellular or delayed).

Irritant contact dermatitis occurs after single exposure to an aggressive substance that is toxic to the skin (eg, castor oil) and in severe cases may cause necrosis. Depends on the concentration of the aggressor agent and occurs in all individuals, depending on the penetration and thickness of the stratum corneum.

There is a concentration threshold for these substances above which they cause acute dermatitis and below which they do not produce it. This differentiates contact dermatitis by irritants from allergic contact dermatitis, which depends on sensitization and occurs only in sensitized individuals. Depending on the degree of sensitivity, small amounts of the aggressor can trigger a reaction.

Contact dermatitis due to irritants is a toxic phenomenon and is limited to the area of exposure and therefore always has well-defined edges and does not usually extend. Allergic contact dermatitis is an immune reaction that tends to affect the surrounding skin (dissemination phenomenon) and may extend beyond the affected sites.

MOST COMMON IRRITANT AND TOXIC AGENTS

  • Soaps, detergents, hand cleansers without water.
  • Acids and alkalis: hydrochloric acid, cement, chromic acid, phosphorus, ethylene oxide, phenol, metal salts.
  • Industrial solvents: solvents with coal tar, petroleum, chlorinated hydrocarbons, solvents with alcohol, ethylene glycol, ether, turpentine, ethyl ether, acetone, carbon dioxide, DMSO, dioxane, styrene.
  • Plants: Euphorbiaceae (tabaibas, poinsettias, manzanillo tree), Ranunculaceae (buttercup), Cruciferae (black mustard), Urticaceae (nettle), Solanaceae (pepper, capsaicin), Opuntia (cactus).
  • Others: fiberglass, wool, synthetic clothing, fire retardant fabrics.

Eczema
Figure 3-1. The rash is characterized by massive erythema with formation of vesicles and blisters and is limited to the sites exposed to the toxic agent.
Acute contact dermatitis
Figure 3-2. Acute contact dermatitis in the hand, caused by industrial solvents. There is massive formation of blisters in the palm of the hand

CONTACT DERMATITIS BY IRRITANTS

Clinical manifestations:
Symptom. (burning sensation, itching, stinging) can occur in terms of a few seconds after exposure (immediate symptoms), for example with exposure to acids, chloroform and methanol. Late symptoms occur in 5 to 10 minutes, reaching their maximum in 30 minutes and are caused by substances such as aluminum chloride, phenol, propylene glycol and other substances. In contact dermatitis due to late irritants, skin symptoms do not start until 8 to 24 hours after exposure (eg, anthralin, ethylene oxide, benzalkonium chloride) and are accompanied by burning sensation rather than pruritus.

Cutaneous manifestations:
They appear minutes after exposure or until after 24 h. Lesions range from erythema to vesicle formation (Figures 3-1 and 3-2) and cause burn with necrosis. Clearly framed erythema and superficial edema correspond to the site of application of the toxic substance (Figure 3-1). The lesions do not spread beyond the contact site. In the most severe reactions, vesicles and blisters appear (Figures 3-1 and 3-2) with formation of erosions or even frank necrosis, as occurs with acidic or alkaline solutions. No papules are formed. The configuration is often anomalous or linear (“drip effect”) (Figure 3-1).

Evolution of the injuries:
Erythema with a matte-looking surface (Figure 3-1) → formation of vesicles or blisters) (Figs 3-1 and 3-2) → erosion → crust formation → crust detachment and peeling or (in cases of chemical burn) erythema → necrosis → necrotic tissue detachment → ulceration → scarring. Distribution. Isolated, localized or generalized lesions, depending on the type of contact with the toxic substance. Duration. Days or weeks, depending on the damage to the tissues.

PREVENTION AND TREATMENT OF THE CONTACT DERMATITIS BY IRRITANTS


Prevention

  • Avoid exposure to irritants or caustics with the use of protective clothing (eg, protective goggles, covers, gloves).
  • If contact occurs, wash with water or a weak neutralizing solution.
  • Creams as a barrier.
  • In occupational contact dermatitis due to irritants that persists despite adherence to the aforementioned measures, labor relocation may be necessary.

Treatment (Acute)

  1. Identify and eliminate the causal agent.
  2. Wet dressings with Burow solution, which are changed every 2 to 3 h.
  3. Large vesicles can be drained, but the vesicle is not removed.
  4. Topical preparations of glucocorticoids of classes I-II. In severe cases, systemic glucocorticoids may be indicated.

Treatment (Subacute and chronic)

  1. Potent topical glucocorticoids and adequate lubrication. As the healing occurs, lubrication is continued.
  2. Topical calcineurin inhibitors are usually not strong enough to suppress chronic inflammation in the hands with sufficient intensity.
  3. In contact dermatitis due to chronic irritants of the hands, the effect of tolerance can be achieved in most cases with topical treatment (compresses or baths).

ALLERGIC CONTACT DERMATITIS

Allergic contact dermatitis is a systemic disease defined by T cell-mediated inflammation. It is one of the most frequent, irritant cutaneous problems. It usually occurs due to a new exposure to a substance to which the individual is sensitized.

Clinical manifestations:
The rash begins in an individual sensitized 48 h or in terms of days after contact with the allergen; Repeated exposures cause gradually more intense reactions, that is, the rash gets worse. The site of the eruption is limited to the exposure site. Symptoms: Intense itching; in severe reactions, also pain and itching.
General symptoms:
“Acute disease syndrome”, which includes fever, but only in severe cases of allergic contact dermatitis (eg, exposure to poison ivy).

Mouth Eczema
Figure 3-3. Acute allergic contact dermatitis by lipstick. The patient had hypersensitivity to eosin. Note the bright erythema with microvesicle formation. With careful inspection, a papular component can be identified. In this stage, there are well-defined edges.

 

Allergic contact dermatitis of the hands
Figure 3-4. Allergic contact dermatitis of the hands: chromates. Confluent papules, vesicles, erosions and scabs on the back of the left hand in a construction worker with chromate allergy.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Thank you for the wonderful article

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