8. It is wise to note certain differences, not only as to the general nature and character of cutaneous diseases as they exist in the old and young, but also in reference to the same diseases as it occurs in the old and young. The cutaneous diseases of childhood are essentially distinguished from those of the adult, in that they are uncomplicated by organic diseases of the internal organs, and by those more complex and profound perversions of nutrition which arise from overworked or badly used organs, such as gout, dyspepsia, free retention of excreta in the blood, rheumatism, and so on. They contrast with those in the old by the absence of coincident degenerative changes in the body, which are to be the lot of the man who passes the meridian of life. The cutaneous diseases of children are uncomplicated in this respect, and speaking generally, they are the result of the misuse of pabulum supplied to the body, or the direct consequence of improper diet. The case of eczema infantile may be taken as an example. But there is a differences in constitutional conditions-the diathetic conditions in the child who suffers from skin diseases are different from those of the adult or aged. It does not take any long time to see how frequently the subjects of skin diseases in the young are strumous, and what an influence this diathesis has on the skin diseases of the young as contrasted with those of the middle aged and of an age beyond the latter period of life; that syphilitic affections other than those hereditarily transmitted are specially the privilege of the adult, and so on; that in the advanced in years there are not only complicating organic diseases of internal organs, blood alterations due to mal-assimilation, degenerative tissue changes such as cancer, but disease specially connected with decay of the nervous system, as in senile pruritus. But to put what I wish to enforce in a few words, I may say that, as regards kind, the diseases of children are the result of malnutrition from deficient or bad feeding; those of the adult the result of mal- assimilation; those of the aged the result of degenerative changes. As regards complications, diseases of the young are often closely connected with the strumous diathesis especially; those of the adult with functional derangements of internal organs and mal-assimilation, such as dyspepsia, hepatic and renal torpor- and with the diathetic conditions, phthisis, rheumatism, and the commencement of gout; those of the aged are linked with nerve pareses and degenerations of the skin, as evidenced by increased pigmentation, atrophy of the glands, and of the nerves in the papillae, and also with organic diseases of important internal organs. All this is important therapeutically.
9. It is to be remembered that there is a difference in the conditions associated with skin diseases, as they occur in hospital and private practice. The constitution of the hospital patient is depraved by mal-hygiene and want of proper food, that of the private patient is depraved, no doubt by want of hygiene oftentimes, but also by over loading of the digestive organs, and not from actual want of food. But more than this; the nervous system participates in the latter much more actively in helping, controlling, or modifying the existing disease; and this as the result of the luxury enjoyed by the rich, and the greater mental toil undergone by the busy man of the middle classes, the effects of which, in both cases, are felt by the offspring. The old amongst the hospital patients show especially nervous symptoms connected with physical decay, and at the two extremes of life the evil consequences of uncleanliness are most marked, because there is less power to resist its influence-in the hospital patient.
10. There are differences in the same disease as seen in this and other countries, as well as a distinction to be drawn between the several kinds of cutaneous affections occurring in this country and abroad. There is, indeed, a nationality of disease as well as of character or physique.
11. A very close relation exists in many instances between cutaneous disorders and functional disturbances in internal organs. Dr. Singer calls attention to this relation, and thinks that it is more frequent than is generally known, as the symptoms, meteorism, flatulence, eructations, loss of appetite, and constipation, may be lacking. Examination of the urine with detection of the greater or less excretion of indican will give one an index of how matters stand. Urticaria is nearly always accompanied by digestive disturbances. In the so-called idiopathic urticaria the amount of indican in the urine is nearly constantly increased. Collect the twenty-four hour’s quantity and test from that as it varies during the day. He employed Obermayer’s reagent. In certain forms of facial acne, and in nearly all cases of senile pruritus, he found a constant relation between the skin eruption and increased intestinal fermentations at the lower portion of the small intestine. In some instances hyperaemic changes in the skin and mucous membrane have a common origin, as in lichen planus and pityriasis rubra, from disturbance of the sympathetic for example, and this is the explanation of the coincidence in the two diseases named, of the skin changes, and pyrosis, menorrhagia, and the like. In other instances the changes in skin and internal organs, instead of having a common origin, react the one upon the other, and the important point to notice is this: that the cutaneous troubles may be excited and intensified by internal troubles. There are four organs whose derangement excites or intensifies skin mischiefs. The stomach, the liver, the kidney, and uterus. In the vast majority of cases it is rather intensification than excitation that the practitioner has to deal with.
12. It is important always to be aware of the fact of the bias impressed upon skin diseases by various diatheses-especially the syphilitic, the gouty, the strumous, and the nervous.
13. Observers should accustom themselves to examine microscopically the morbid products of skin diseases. The surgeon and the physician obtain most valuable indications from the examination of the minutest portions of morbid tissue and the juice it may yield; and the dermatologist is much to blame for an omission in this respect. The microscope affords very valuable assistance in the differential diagnosis of herpes, eczema, psoriasis, and tinea especially. For instance, inflammatory products are absent in psoriasis, present in the other three diseases; whilst in all forms of parasitic disease resembling herpes and eczema, as in so-called eczema, marginatum, fungus elements are detected, provided proper care is observed.
