Contact Dermatitis

A contact or exogenous dermatitis is one in which an external irritant is the m?st important cause; but a constitutional factor undoubtedly also plays a part, and accounts for the fact that only a certain proportion of a community, in contact with the same irritant, develops dermatitis. Most cases of contact dermatitis clear up quickly when the irritant is removed, but in some the rash persists and sPreads to other areas because the patient has a constitutional tendency to. e^elop eczema. Contact dermatitis is responsible for a great loss of manpower j*1 mdustry, and causes disability amongst the general population, especially in housewives.. The clinical appearances and histopathology of patches of eczema or derma-are identical; the former term is commonly used when constitutional factors are thought to be responsible for the condition, and the latter when external actors predominate. Unfortunately dermatitis suggests occupational dermatitis to the worker, and it is advisable to avoid the use of this name whenever possible, ^uless an occupational cause is likely, e.g. seborrhoeic eczema instead of Seborrhoeic dermatitis. The first clinical finding is erythema of the affected area. Papules appear and then vesicles which burst and give rise to weeping. Action may then supervene or the exudate may dry up and leave a scaling ?0ridition. Irritation is a prominent symptom and the rubbing and scratching CaUse thickening or lichenification of the skin. /he irritants can be divided into primary and sensitizing irritants. The P^niary ones are those which, used repeatedly, or in sufficient concentration, ^ affect the skins of most people. Examples of these are the strong acids,. ahs and soaps, degreasing agents such as petrol, lime and cement. Sensitizing lrntants are those to which the skins of some people become sensitive after one ^any contacts. Primulas, aniline dyes, turpentine, penicillin and strepto-^cin, antiseptics, and elastoplast are a few well-known substances of this group. most any chemical can sensitize the skin and cause dermatitis in a small ^r?portion of people, but it is often very difficult to convince a patient that his *"ash has been produced by something which he has been handling for many ears> and the patch test, if positive, is helpful in these cases. Primary irritants ?bably account for about eighty per cent of cases of contact dermatitis.