Eczema is an inflammatory reaction of the skin of a different type, and probably due to a diversity of causes, often complicated. For a patient may inherit a state of nutrition predisposing to it, or acquire such by his habits and mode of life, and then various exciting causes come into play and complete the story. Eczema is not a parasitic disease, although the pyogenic cocci find a congenial soil in the inflammatory area, and are frequently a cause of the persistence of the trouble.
To repeat what we have said about other reactions it is important to bear in mind that, although many irritants are potent enough to inflame any skin (see Artificial Dermatoses), there are states of malnutrition brought about by inherited or acquired influences which make the skin abnormally vulnerable. In such cases external irritants of little potency, such as a cold wind or sun exposure, will suffice to excite an eczema. Thus we constantly observe masons, bakers, polishers, laundry-women, scrubbers, etc., who suddenly become attacked with eczema, because the resistance of their skin tissues has diminished from various causes. These causes comprise all the factors that go to make up the mode of life and inherited tendencies. Thus we find associated with the eczema reaction such states as anaemia, gout, liver and gastro-intestinal disorders, oxaluria, lithiasis, diabetes, obesity, asthma, chronic bronchitis and interstitial nephritis. It is almost universally held that various disorders of metabolism, the excessive intake of foods or certain foods especially with a sedentary life, and deficient elimination may strongly predispose to eczema, and it is possible that certain toxic products may actually be the excitants, but our knowledge is not very sure on this point. Certain it is that we meet with many cases in which no clue to external excitement can be traced, and on the other hand it is sometimes impossible to detect any metabolic disorder. The state of the nervous system probably has a marked influence, either directly or indirectly, in the causation of certain cases of eczema. We meet with it in neurotic individuals who live carefully, and attacks seem to be excited sometimes by strong mental strain. It will be gathered from these remarks that in planning a treatment for a case of eczema it will be desirable to make an exhaustive examination into the general health of the subject, and the functioning of the various organs, especially the gastrointestinal tract, liver and kidneys; to note the mode of life and habits, especially as regards the quality and quantity of the diet, the consumption of alcohol and amount of tobacco smoked. The diet arranged must obviously depend to some extent on the condition present, whether gout, diabetes, etc. Eczema may occur in low states of nutrition from want of proper food; on the other hand, in most cases it is well to impress the necessity of slow mastication; to diminish the quantity of food; to take easily digestible bland foods such as, for dinner, a sole, chicken and milk pudding; to avoid pig flesh, sweets, pastry, and fruits, piquant sauces, oily fish, curries, and to cut off alcohol or greatly limit its use. A little sound whisky, if any alcohol, is usually allowed. Salted foods are very commonly prohibited, and tea and coffee may not agree. In acute and obstinate cases it is useful to cut down the meals to a minimum, and even for a time put the patient on special diet (milk, lacto-vegetarian, etc.), the details of which are given elsewhere.
As for the very common and troublesome infantile eczema we ought to be in a position to understand the etiology, for many complicated factors acquired by the adult are absent. Nevertheless, we are very far from thoroughly understanding the etiology. Allowing that the cutaneous nervous system is in an excitable condition in the infant, we have two categories of provocatives, external irritants of various kinds and gastro-intestinal troubles often due to improper feeding as regards quantity and quality. It is therefore of the first importance to have the child fed on proper principles in every respect. Some of the most troublesome cases are those in which infants seem to have idiosyncrasies against certain foods. Having spent a large portion of my life in observing babies suffering from eczema, I have watched many who were apparently, apart from their eczema, perfectly healthy in every respect and properly fed; and in my opinion a great deal of so-called infantile eczema belongs to the pityriasis group and is purely a skin disease, except that the susceptibility of the soil is important. It is notable that the eczema so frequently commences by the scalp, and descends over the face and elsewhere. It is often characterized by pityriasic patches which become readily "ecze-matized" by external irritation, and is then indistinguishable from true eczema.