Aprovechamiento hídrico y consecuencias sobre el estado de las aguas superficiales

threshold to pruritus. It may arbitrarily be divi­

ded into infantile, childhood/adolescent and adult variants.

In infants it usually appears about the third months of life. The child is usually fair, fat, anxious, with shiny eyes and glassy expression.

The face, particularly the cheeks are the usually affected site. The lesions are erythematous and dry or mildly oozing. It is characterized by remis sion and relapses. However, it usually disappears at the age of 2 years. In a high proportion of patients, the condition recurs in late childhood, adolescence or early adult life.

At this time, dermatitis tends to localize in the flexural areas, the antecubital and popliteal fossae, neck, eyelids, and behind the ears. At times the eruption may become generalized.

The features are essentially of erythema, edema, vesiculation, and oozing. In the adult phase, the skin may be lichenified.

Several of the patients of atopic dermatitis have atopic diathesis, characterized by history of hay fever, asthma and/or urticaria in the patient or in the family.

Seborrheic dermatitis: It is the part compo nent of seborrheic diathesis which includes acne vulgaris, rosacea, seborrheic dermatitis, and labile personality. The dermatitis is characteri­

zed by scaly patches, the margins of which are indistinct. The lesion is erythematous with

25

Eczema/Dermatitis scales which are greasy and greyish white or yellow in color. It has a centrocorporeal (shower bath) distribution with a predilection for scalp, eye brows, forehead, paranasal folds, retro­

auricular areas, presternal, interscapular, and pubic areas. In obese patients, the intertriginous folds of the trunk may also be involved.

Nummular dermatitis: It presents with cha rac­

teristic round, nummular, coin­like lesions, distributed on the extensor surface of the extre­

mities, posterior aspect of the trunk, buttocks, and lower legs. The dermatitis may remain localized as a few small, scaly patches or there may be a gradual relentless appearance of new lesions. Eventually the lesions may involute in 2­3 months time.

Stasis dermatitis: It usually affects persons like teachers, laborers, rickshaw­pullers, athletes, etc. whose work requires long hours of stan­

ding. This predisposes to varicose veins with tortuous, dilated veins over the legs. It is followed by stasis of blood on the dependent parts of the legs.

Over a period of time, there is diapedesis of red blood corpuscles into the surrounding tissue and this manifests as petechiae over the skin surface, usually confined to around the ankles.

Subsequently, the red blood cells are hemolyzed

and hemosiderin is liberated. It is evident as pigmentation over the area. This acts as foreign substance and evokes eczematous response.

Also the oxygenation of the part is impaired resulting in ulceration. The ulcer margins may develop pseudoepitheliomatous hyper plasia and sub sequent malignant transformation.

ExogEnous EczEmas

Air-borne contact dermatitis: It is usually en­

coun tered in those who work in open and are exposed to dust, pollens, and other particles suspended in the air. The laborers, farmers, industrial workers, gardners are often affected by air­borne contact dermatitis. The particles tend to lodge in body folds. Repeated exposure to the allergen causes sensitization and sub­

sequently there is eczematous response in the form of erythema, edema, vesiculation, oozing and crusting, usually confined to the flexures.

On withdrawal from the environment, the eczema subsides. However, when the person returns to the same surroundings, there is a relapse of dermatitis (exposure­withdrawal test) (Figs 5.1A and B).

Photodermatitis: It is the general name used to define the abnormal eczematous response to the stimulus of light. It is usually evoked in

Figures 5.1a and B: Air-borne contact dermatitis: Erythema, edema scaling

a B

26

Textbook of Clinical Dermatology association with chemicals which are innocuous

to the skin in absence of light exposure.

However, when the skin is challenged with appropriate concentration of the agent and the wavelength of the light, dermatitis is produced.

These photo sensitivity reactions may either be photoallergic or phototoxic, depending upon whether the immune system is participating or not. The photoxic reaction may be elicited in any indivi dual provided there is enough light energy of appropriate wavelength and ade­

quate concen tra tion of the agent. However, in photoallergic dermatitis, the absorbed light energy promotes a photochemical reaction bet­

ween the chemical and skin proteins resulting in the formation of photoantigen. There is sensi­

ti zation to this photo antigen and on subsequent exposure, an eczematous response is elicited.

There is usually a prodrome of itching and/

or burning on areas exposed to sunlight, namely forehead, butterfly area of the face, tip of the nose, pinna, ‘V’ of the neck, and extensor aspects of the forearms. This is followed by eczematous response in the form of erythema, edema, vesi­

culation, and oozing. On healing, these areas may show hyperpigmentation. Exposure­withdrawal test is positive in photo dermatitis also. When the patient is withdrawn from sunlight and confined to a darkroom, the eczema subsides. However, re­exposure to sunlight again precipitates the eczematous response. Photopatch test may also be perfor med by using a blackened X­ray film with a window. This is applied to an area exposed to light. Eczematous response would be elicited on the skin underneath the window which was accessible to light exposure (Figs 5.2A and B).

diagnosis

The diagnosis of acute eczema is made by the presence of cardinal clinical features of

Figures 5.2a and B: Infectious eczematoid dermatitis (IED)

erythema, edema, vesiculation, and crusting, and associa ted itching. The chronic lichenified dermatitis is characterized by hyperpigmenta­

tion, thickening of the skin, and exaggeration of skin markings. The clinical features of respec­

tive eczemas (vide supra) should help in forming the diagnosis. Office procedures, namely patch test for contact dermatitis, photo patch test for photodermatitis and exposure—withdrawal

a

B

27

Eczema/Dermatitis

Table 5.2: Treatment of eczema/dermatitis

Types of eczemas Mainlines of treatments Other associated treatments

Atopic eczema A. Topical corticosteroids as creams Explain regarding the relapses

Infantile: Hydrocortisone butyrate (Locoid) and remission.

Adolescent: Bland compresses in exudative stage, followed by application of topical corticosteroids like Betamethasone valerate or Beclomethasone dipropionate (Diplene) Adult: Topical corticosteroids, if lichenification has occurred,

prefer ointments.

B. Antihistamines

Phenergan 10 to 25 mg thrice daily

Practin 4 mg thrice daily.

Seborrheic eczema Topical corticosteroids like betamethasone-17 valerate Corticosteroid lotions (Flucort

(Diplene) applied twice or thrice daily. lotion) and cetrimide

Oral corticosteroids if dermatitis is severe. shampoo.

Pompholyx Oral corticosteroids like decadron (0.5 mg) 2 tabs thrice Treat the focus of infection

daily or Prednisolone 40 mg/day. with suitable antibiotics.

test for air­borne contact dermatitis (ABCD) are useful supple ments in diagnosis.

TrEaTmEnT

The corticosteroids form the mainstay of treat­

ment. These may be combined with antihista­

mines. Antibiotics may be indicated in asso cia ted

secondary infection. Topical bland compres­

ses like potassium permanganate, boric acid or aluminium subacetate are essential (Table 5.2).

rEcommEndEd rEading

1. Sehgal VN, Jain S. Eczema/dermatitis. J Indian Med Assoc 1993;91:78­79.

Exfoliative dermatitis/erythroderma is an ext­

reme state of skin irritation affecting either whole or most of the skin surface. It is conceived as a secondary or reactive process to a host of cuta­neous­and/or­systemic­affliction.­How­ever,­

a proportion of cases belong to the idiopathic group.

The etiology of exfoliative dermatitis may show geographical and regional variations.

In­ India,­ the­ important­ causes­ of­ it­ are­ as­

follows:

I. Pre-existing skin dermatoses

They may give rise to exfoliative dermatitis per se or it may be the result of treatment taken for­ these­ disorders.­ In­ order­ of­ frequency,­

the most common skin dermatoses which may progress to erythroderma are:

•­ Psoriasis

•­ Air-borne­contact­dermatitis

•­ Phytophotodermatitis

•­ Staphylococcal­ scalded­ skin­ syndrome­

(SSSS)

•­ Seborrheic­dermatitis

•­ Atopic­dermatitis

•­ Photosensitive­dermatitis

•­ Pityriasis­rubra­pilaris­(PRP)

•­ Stasis­dermatitis

•­ Norwegian­scabies

•­ Ichthyosiform­dermatoses.

6 Erythroderma/Exfoliative

In document La Sagra Toledana, un espacio de oportunidades entre influencias metropolitanas: propuesta de Plan de Ordenación Territorial (página 34-43)