Eczema,_urticaria

Eczema / Dermatitis Dr. Sahar Ismail

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Eczema is an inflammatory skin reaction characterized histological y by spongiosis and clinical y by itching, redness, scaling and papulovesicular eruption. The terms eczema and dermatitis are general y regarded as synonymous. Eczema/dermatitis may be presented as Acute, subacute or chronic. In the acute eczema, erythema, edema, oozing and papulovesicular eruptions are the presenting features.

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In the sub-acute eczema, the lesion shows less erythema, edema and oozing with scaling and crusting. In the chronic eczema, the lesion shows dryness and thickening (lichenification).

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Varieties of eczema /dermatitis:•Contact dermatitis.•Atopic dermatitis.•Infective dermatitis.•Seborrhoeic dermatitis.•Discoid eczema.•Pompholyx. •Gravitational eczema. •Pityriasis alba.

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Contact dermatitisThere are 2 types of contact dermatitis: irritant and al ergic contact dermatitis. A-Irritant contact dermatitis: Irritant dermatitis is an inflammatory reaction in the skin resulting from exposure to a substance that causes an eruption in most people who come in contact with it if a sufficiently high concentration of the substance is used. No previous exposure to the substance is necessary, and the effect is evident within minutes or a few hours at most. There are many substances acting as irritants that wil produce a non-al ergic inflammatory reaction of the skin. Of the common irritants are: alkalies, weak acids, detergents, organic solvents and topical medicaments.

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B-Allergic contact dermatitis: Al ergic contact dermatitis is an acquired sensitivity to various substances that produce inflammatory reaction in only those who have been previously exposed to the al ergen (sensitizer) i.e. does not occur from the first exposure. It results from a specific acquired hypersensitivity of the delayed type i.e. cel -mediated immunity. Persons may be exposed to the al ergens for years before developing dermatitis.

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Common allergens (sensitizers): Elements e.g. chromium (in cement), nickel (in artificial jewelleries). Cosmetics e.g. balsams, perfumes. Rubbers e.g. clothes, shoes. Medicaments e.g. penicillin, neomycin sulphonamides.Insecticides, dyes, tar, plants.

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Clinical picture: The clinical pictures of irritant and allergic contact dermatitis are more or less the same.The primary signs in contact dermatitis are erythema, swelling, papules and papulo-vesicles.If contact dermatitis persists, it may be due to continued or repeated exposure to the allergen or irritant. It becomes dry, scaly and lichenification and fissuring may develop later. The site and morphology of the lesion may point to the cause.

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Diagnosis: History. Site and morphology of the dermatitis.Patch testing in allergic contact dermatitis. Treatment:Detection and avoidance of the cause.The use of protective measures e.g. gloves. Treatment of the dermatitis.

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Atopic dermatitis

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Atopic dermatitis is an itchy, chronic, relapsing inflammatory skin condition, frequently associated with other atopic conditions (asthma, hay fever, atopic dermatitis) in the individual or other family members.Clinical Picture: Atopic dermatitis may start at any age. The distribution of the eruption varies with age, as described below.

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Infantile phase (2 months- 2 years): The lesions frequently start on the face but may occur anywhere. The lesions consist of erythema and edematous papules. The papules are intensely itchy, and may become exudative and crusted. Secondary infection and lymphadenopathy are common.

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Childhood phase (2-12 years) The sites most commonly involved are the elbow and knee flexures, sides of the neck, wrists and ankles. The erythematous and edematous papules tend to be replaced by lichenification, true eczematous lesions with vesiculation may occur. Itching is also intense.

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•Adult phase (12 years and more): The picture is similar to that in later childhood, with lichenification, especially the flexures and hands.

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Infective dermatitis

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Infective eczema is eczema which is caused by microorganisms or their products, and which clears when the organisms are eradicated. Often it develops about a discharging abscess, sinus, or ulcer as an area of erythema with microvesicles. Treatment:Treatment of the infection in addition to treatment of the eczema.

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Seborrhoeic dermatitis

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It is a chronic dermatitis, which has a red sharply marginated lesions covered with greasy scales and distributed in areas with a rich supply of sebaceous glands namely the scalp, face and upper trunk . The yeast Malassezia may have a role in the etiology of the disease especial y in adults.

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Clinical picture:Dandruff (visible desquamation from the scalp surface) appears to be the precursor of seborrhoeic dermatitis, and this may progress through redness, irritation and increasing scaling of the scalp to seborrhoeic dermatitis.Seborrhoeic dermatitis commonly originates in hairy skin, and involves the scalp, face, pre-sternal and inter-scapular regions and the flexures. The lesions tend to be dul or yellowish red in color and covered with greasy scales. The lesions may be generalized, with erythema, scaling, oozing and pruritus and may progress to erythroderma.

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Treatment: Dandruff is usually treated by medicated shampoos as ketoconazole and selenium sulphide shampoos. Seborrhoeic dermatitis of the glabrous skin is treated as eczema.

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Discoid eczema (Nummular eczema)

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Discoid eczema is characterized by circular or oval plaques of eczema with a clearly demarcated edge. Clinical picture:The diagnostic lesion of discoid eczema is a coin shaped plaque of closely set, thin-walled vesicles on an erythematous base. Itching is usual y severe. Middle aged men are most frequently affected. Discoid eczema usual y begins on the lower legs, dorsa of hands, or extensor surfaces of the arms.

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Pompholyx (Dyshidrotic eczema)

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Pompholyx is characterized by sudden onset of crops of clear vesicles, which appear deeply seated on the palms and soles. Vesicles may become confluent and present as large bul ae. Itching may be severe. The attack subsides spontaneously, and resolution with desquamation occurs in 2-3 weeks.

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Gravitational eczema (Venous or stasis eczema)

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Gravitational eczema is commonly secondary to venous hypertension, usual y occurs in the lower leg and affects mainly middle-aged or elderly females. The eczema is usual y accompanied by other manifestations of venous hypertension, including varicosity, edema, purpura, hemosiderosis and ulceration.

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Pityriasis alba

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Pityriasis alba is a type of non specific dermatitis, of unknown origin. It is more common in children. It is characterized by erythematous scaly patches which subside to leave areas of hypopigmentation. The lesions are often confined to the face.

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Treatment of eczema:The cause should be removed or avoided.Wet dressings e.g. potassium permanganate 1/8000 are used for the acute cases.Creams are used for the sub-acute cases.Ointments are used for the chronic casesAntihistamines for itching.Antibiotics, local and systemic for secondary infection.Corticosteroids, local for the majority of cases and systemic for the severe, generalized or resistant cases.

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Urticaria

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Urticaria is a transient eruption of erythematous or edematous swellings of the dermis and is usual y associated with itching. The urticarial wheal results from increased capillary permeability, which al ows proteins and fluids to extravasate.  Increased capil ary permeability results from increased release of histamine from mast cel s.

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Classification: Urticaria may be acute with complete resolution within 6 weeks of onset or chronic lasting more than 6 weeks. It can also be classified into: immunologic, non-immunologic or idiopathic.

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Etiologic factors:•Drugs e.g. penicil in, salicylates, morphine, nonsteroidal anti-inflammatory drugs and codeine.•Foods e.g. seafood, strawberries, chocolate, nut, cheese, eggs and milk, and food additives as tartrazine. •Insect bites and stings. •Physical agents e.g. heat, cold and physical injury. •Inhalants e.g. nasal sprays, pol ens and animal dander. •Infections e.g. focus of infection in the sinuses, teeth or tonsils.•Parasitic infestations e.g. ascaris & ankylostoma. •Emotional stress. It is important in cholinergic urticaria.

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Clinical picture: Itchy erythematous macules develop into wheals consisting of pale-pink, edematous, raised skin areas often with a surrounding flare. They occur anywhere on the body, in variable numbers, sizes and shapes and last a few hours and resolve within 24 hours. Mucosal swel ings occur inside the oral cavity, tongue, pharynx and larynx. In 50% of cases, there is associated angioedema.

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Special varieties of urticaria •Papular urticaria.

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•Physical urticaria e.g. dermographism, cholinergic urticaria, cold urticaria.

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•Angioedema (angioneurotic edema) is a type of acute urticaria affects the most distensible tissues e.g. eyelids, lips, lobes of the ears and external genitals with circumscribed edema. The swelling affects the deeper parts of the skin or the subcutaneous tissue with the overlying skin unaltered. It may also affect the mucous membranes. Affection of the larynx is a life threatening condition. Itching is usual y absent.

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Treatment: Detection and avoidance of the cause. Antihistamines.Corticosteroids (systemic) in severe cases. Adrenaline 0.2-0.5 ml of 1:1000 solution given subcutaneously in severe cases associated with angioedema. Topical antipruritic e.g. calamine lotion.

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Papular urticariaPapular urticaria is a characteristic reaction to insect bites as mosquitoes or fleas that affects mainly infants and children.

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Clinical pictureThe lesions develop mainly on the upper and lower extremities particularly the forearms and legs. Initially, an extremely itchy urticarial wheal develops at the site of the bite, and this is succeeded by a firm pruritic papule, which may be surmounted by a tiny vesicle. Itching is an almost constant symptom and secondary infection is a common complication. The condition usually subsides spontaneously.

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Treatment•Control of insects. •Antihistamines. •Topical antipruritics e.g. calamine lotion.

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Prurigo of Hebra

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It is a pruritic papular eruption believed to be a continuation of papular urticaria, which caused by insect bites. Clinical Picture It is a disease of children and affects mainly the extensor surfaces of the extremities but in long standing cases, other areas may be affected. The lesions are characterized by excoriated papules and dryness and thickening of the skin (lichenification). Lymph-adenopathy is common. Spontaneous cure usual y occurs in adolescence.Treatment- As for papular urticaria

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Erythema multiforme

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EM is an acute self-limited eruption of the skin and mucous membranes characterized by the distinctive target or iris lesion.Etiology:The precise etiology is unknown. The trigger factors are: Viral infections e.g. herpes simplex.Mycoplasma pneumoniae.X-ray therapy.Drugs e.g. sulphonamides, non-steroidal anti-inflammatory drugs.Lupus erythematosus.Carcinoma, lymphoma.

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Clinical picture Erythema multiforme is a self-limited, recurrent disease, usual y of young adults. It lasts 1 to 4 weeks.

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Erythema multiforme minor: (80% of the cases) It occurs seasonally in the spring and fall. There is no prodrome. The lesions are dull red maculopapules in addition to the characteristic target or iris lesions. A typical target lesion has 3 zones: a central area of dusky erythema or purpura, middle paler zone of edema and an outer ring of erythema.Classical y, the backs of the hands, palms, wrists, feet and extensor aspects of the elbows and knees are affected, less commonly the face. There may be erosions or bul ae on the mucous membranes

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Erythema multiforme major (Stevens-Johnson syndrome): It is the severe form of the disease and frequently accompanied by a febrile prodrome.Mucous membranes show extensive bul ae formation and erosions. The skin lesions may be in the form of maculopapules, bullae or pustular lesions. The eruption usual y heals without sequels.

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Treatment:Treatment or eradication of the trigger factor.Antihistamines, and antibiotics if there is secondary infection.Topical corticosteroids, and systemic therapy in severe cases.Management in a burn unit if the bul ous lesions and erosions are extensive.Care of the mucous membrane lesions.

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Erythema nodosum:

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Erythema nodosum is a nodular erythematous eruption affecting mainly the extensor aspects of the legs, and most cases occurring in young adult women.

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Clinical picture:The eruption consists of bilateral, symmetrical, deep and tender nodules. The skin over the nodules is red, smooth and shiny.The onset is acute, frequently associated with malaise, leg edema and arthritis or arthralgia. The nodules last few days or weeks, and then slowly involute without scarring or atrophy.

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Etiology: As in erythema multiforme the etiology is unknown. The trigger factors may be:Streptococcal infection.Tuberculosis.Intestinal infections e.g yersinia, salmonel a, shigel a.Fungal infections e.g. histoplasmosis, sporotrichosis.Sarcoidosis.Drugs e.g. sulphonamides, contraceptive pil s.

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Treatment Treatment or eradication of the trigger factor.Rest in bed.Supportive bandages or stockings.Acetyl salicylic acid or non-steroidal anti-inflammatory drugs.

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Drug eruptions

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Drug eruptions are probably the most frequent of all manifestations of drug sensitivity. They may arise as a result of immunological al ergy directed against the drug itself, a reactive metabolite or some contaminant of the drug or more commonly, by non-immunological mechanisms.Certain drugs are commonly associated with a specific eruption, most drugs are capable of causing several different types of eruption e.g. ampicil in usually causes a morbil iform rash, but it can cause, fixed drug eruption, erythema multiforme, Henoch-Schönlein purpura and serum sickness.

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Fixed drug eruption: Fixed drug eruptions characteristically recur in the same site or sites each time the drug is administered. The drugs commonly cause this eruption are: sulphonamides, tetracyclines, phenol-phthalein (laxative), non-steroidal anti-inflammatory drugs, barbiturates and tranquillizers.

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Clinical picture:  The lesion usually presents as sharply marginated, round or oval itchy plaques of erythema and edema becoming dusky violaceus or brown, and sometimes vesicular or bullous. Lesions are commoner on the limbs, but about half the cases occur on the oral and genital mucosa. Characteristically prolonged post-inflammatory hyperpigmentation results.

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Treatment:  The suspected drug must be stopped. Oral antihistamines. Systemic corticosteroids in severe cases. Topical anti-pruritics and steroids.

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