Dermis:

• • Vasodilatation in the papillary dermis and also lympho – histiocytic infiltrate accompanies it.
  • Polymorphs and eosinophils are seen in acute eczema and in chronic stage infiltration is dense and mixed.

Etiology:

• • Dermatitis and also eczema are a common problem all over the world.
  • Their incidence is 2-3 per cent of all medical problems in practice.
  • Despite this confusion, the two terms ‘Dermatitis’ and ‘Eczema are in synonymous use by the dermatologists.
  • Moreover, in the practice of dermatology, the first step is to establish the clinical diagnosis of dermatitis and eczema then decide the clinical -morphological pattern.

Basically two factors causes eczema are ,

• • Allergic or sensitive skin
  • And also Exposure to an irritant

Other factors responsible ;

• • Irritants – physical, chemical or electrical
  • Sensitizers – plants, cosmetics, clothing, medicaments and occupational hazards
  • Infections – streptococci, staphylococci, fungus etc.
  • Mental and emotional conflicts, strains and stresses
  • Internal septic focus shedding toxins or causing bacteraemia
  • Diet and state of digestion.
  • Diathesis – allergic, xerodermic, hyperhidrotic or seborrhoeic
  • Drugs – given for the disease or otherwise
  • State of local or general nutrition
  • And also Climate – temperature and humidity

General predisposing causes:

• • Firstly, Age
  • Secondly, Familial predisposing
  • Thirdly, Allergy
  • Debility
  • Climate
  • Finally, Psychological factors

Exogenous eczema:

Contact dermatitis:

• • It is an inflammatory process in skin.
  • The cause is by an exogenous agent or agents that directly or indirectly injure the skin.
  • Injury by a direct toxic action on the skin – refers to irritant contact dermatitis (ICD).
  • Agents that causes allergic contact dermatitis (ACD) induce an antigen- specific immune response.
  • The most common cause of contact dermatitis are ; plants, clothing and footwear, cosmetics, occupational chemicals, medicaments.
  • Removal of the offending agent is the first and foremost step.
  • And so the eruption will resolve.
  • Moreover, Administration of high – potency fluorinated topical glucocorticoid is the choice of treatment.

Infective dermatitis:

• • This results from sensitization to certain organisms like streptococci, staphylococci, dermatophytes and yeast organisms.
  • It’s more common in tropical countries.
  • About three-fourths of hospital eczema cases fit into this category.
  • Clinically it is characterized by its slow development, so no vesicles is evident but a crust is formed instead.
  • The patches formed are clearly defined, and there is no erythematous halo, they take the form of circles which by union become polycyclic.
  • The lesion spread not only by direct contiguity but also to the other body folds, parts and hair follicles.
  • Infective eczema can be divided further into three sub-types according to their distribution: post traumatic infective eczema, follicular infective eczema, flexural infective eczema.
  • These eczema responds to mild antiseptic astringents.

Photodermatitis:

• • Photodermatitis resembles an exaggerated sunburn reaction commonly due to phototoxic drugs like psoralens.
  • It is confined to the exposed parts of the body viz., Face, neck, hands, and external surfaces of the forearms and dorsa of feet and the adjoining parts of leg.
  • The integument is sensitive to sunlight and ultraviolet rays. Eruption develops, or becomes aggravated on exposure to light.
  • The common causes of photodermatitis are:
  • 1)drugs like sulphonamides, chlorpromazine, promethazine, declamycin, different hypotensive and anti-diabetic drugs, quindexin in animal feeding stuff etc.
  • 2) foods like figs, buckwheat
  • 3) external application of bithionol, tetrachlorsalicylanilide etc.
  • 4) plants and their products like parsnips, meadow grass, mustards, limeoil, celery, etc.
  • Predisposing factors are: vitamin B complex deficiency, porphyrinuria, seborrhoeic diathesis and liver disorders.