The Scope of Dermatology. Chairman’s Address read In Section of Dermatology and Syphllography, at the Forty-fourth Annual Meeting of the American Medical Association. LOUIS A. DUHRING, M.D. PROFESSOR OF DERMATOLOGY IN THE UNIVERSITY OF PENNSYLVANIA. PHILADELPHIA. REPRINTED FROM THE JOURNAL OF THE AMERICAN MEDICAL ASSOCIATION, FEBRUARY 17, 18%. PRINTED AT THE OFFICE OF THE JOURNAL OP THE ASSOCIATION. 1894. CHICAGO; THE SCOPE OF DERMATOLOGY. LOUIS A. DUHRING, M.D. On the occasion of the last annual meeting of this Section of the Association, the honor to preside over the deliberations of the present meeting was conferred upon me. It affords me pleasure to greet you as mem- bers of the Association, and especially as attendants upon the work of this Section, whose importance I be- lieve must be more fully recognized by the profession with each succeeding year. Before taking up the origi- nal papers to be presented for reading and discussion I would ask your attention for a few moments to con- sider of what dermatology actually consists. The subject, I believe, will not prove uninteresting nor without profit practically. Let me propound the questions, What are so-called skin diseases, and what is their nature? Which diseases are entitled to be designated “ skin diseases?” Is it possible to sep- arate them from the many general diseases accom- panied by cutaneous symptoms? Answers to these questions may at first thought appear easy, and so they seemed to the writer many years ago, when thoroughly imbued with the spirit of local pathology, as taught by his former and respected master Hebra, it was deemed all sufficient to study cutaneous diseases purely objectively. But the questions propounded upon investigation really became difficult problems, especially with the light that has been thrown upon dermatology by compar- atively recent studies. The field, viewed in every direction, has become immensely enlarged, and the amount of work done, both clinical and patho- 2 logical, has been remarkable. I believe, however, that a satisfactory solution of these problems may be found. The questions that immediately confront us are, shall the term, “skin disease,” continue to be used in its ancient sense? Shall the affections of the skin be looked upon as morbid entities, as diseases whole and complete in themselves and confined to the skin? Or, taking a broader view of the subject, shall they be defined so as to include all manifesta- tions that may occur upon the integument irrespec- tive of the symptoms, cause or nature. The first and restricted proposition is that accord- ing to which these diseases were studied and classi- fied a century ago, by Plenck in Germany and by Willan in England, when the list of diseases was small and knowledge of them meagre. I have no desire to belittle the work done by the fathers of der- matology. Willan, especially, was an eminent gen- eral physician as well as a distinguished dermatolo- gist. His treatment for the commoner affections of the skin was both judicious and successful. But the important questions of etiology and pathology were then for most diseases not at all understood. Very little was known on those subjects. The origin of most disease was regarded as “obscure.” The facts that a mite was the sole cause of scabies, and that ringworm was due to a fungus were still unknown, while the observation that almost all the drugs in the Pharmacopoeia are capable of producing dis- order of the skin was not even suspected. Affections of the skin were regarded mainly objectively, and were studied much as a model or a picture might be viewed. Beyond the actual expression on the integ- ument they were not closely investigated; the causes were regarded as obscure: and this mode of study- ing them has held good through decades, up to almost the present date. This method is in no way to be criticized so far as it goes, but by itself and without the assistance of general pathology, it is far too restricted to meet the requirements of existing knowl- edge. It fails to recognize the important fact that the integument is a part of the whole organism, and therefore is subject to the great laws of general pathology, and that diseases affecting the integu- ment are not only to be studied as localized areas of disease, but also in their relation to the system at large. For the majority of cases no laws can be laid down tending to separate the local from the so-called gen- eral diseases. This is particularly true of the inflam- matory affections, and I believe in many cases it is wise not to press such questions too closely in our endeavor to determine these intricate problems. Local pathology, interesting and satisfactory as it is as a study, must never be permitted to outweigh the general process, to which in many instances we must look as the fons et origo of the disease. That some diseases are strictly local in all their aspects will be denied by no one, but it is practically often difficult to decide where to draw the line between such affec- tions and those due to influences and causes re- mote from the skin, as, for example, in the case of the many and often obscure reflex affections. On the other hand, it is not difficult with our knowledge of to-day, to give examples of some true skin diseases. Notably among these may be men- tioned the local parasitic affections,the inflammations due to numerous external causes, as for example the rhus plant and certain of the hypertrophic, atrophic and neoplastic diseases, such as callositas, clavus, cornu, molluscum fibrosum and molluscum epithe- liale. In these affections, and in some others that might be cited, as far as our knowledge extends, the skin is the only organ of the body invaded at any time in the course of the disease. But while this holds true for a considerable number, there are still many that are in reality widespread diseases, the skin being only one of the organs involved by the process. As instances of such may be cited the so-called 4 exanthemata, as well as other eruptive fevers, the eruptions due to various poisoned states of the sys- tem, as in septicaemia, glanders, leprosy and syphilis. There also exists another group of well-known cuta- neous manifestations in which it is diff cult to deter- mine whether the process is really confined to the skin, and whether it does not also involve other structures of the body, as for example the epithe- lium generally, as in pityriasis rubra and derma- titis exfoliativa. Another group would comprise herpes zoster, pemphigus and the like, where the nervous structures, central or peripheral, are in some wav at fault. Still another class consists of diseases which, while eminently skin diseases, are in some cases at least dependent upon certain peculiar states of the economy for their existence, as a type of which psoriasis may be given. As an example of the effect of the state of the system at large upon this disease, I may cite the case of an old gentleman, an experienced physician, whose chronic and inveterate psoriasis had resisted all manner of internal and local treatment, but who upon going to sea immediately experienced relief and a rapid diminution in all the symptoms, so that in less than a fortnight he had practically recovered from a disease which had for a long period proved entirely intractable to our best remedies. Another well-defined disease attacking the skin is eczema. While this is often a local affection, it may also be started into existence and kept up by serious internal derangements of the economy. In the latter cases it must be regarded in part at least as a symptomatic affection, as in the case of other symp- tomatic disorders, as urticaria; for with improve- ment of the digestive and assimilative functions or nervous 8}7stem the eruption improves or disappears. These observations are particularly striking in the case of infants and children. But it is not so much my purpose to specify and to differentiate the local from the general diseases 5 affecting the skin, as it is to direct attention to what I believe to be an important truth in medicine, namely, that many cutaneous lesions which have long been and still are regarded as local skin dis- eases are really cutaneous expressions of certain general pathological processes, due to varied causes. If this proposition, which might be elaborated, be accepted as an accurate observation, it brings us to the point I am desirous of establishing, namely, that our ideas of dermatology should be greatly enlarged. I am firmly of the opinion that this branch of medi- cine should include all morbid manifestations that appear on the skin, whatever may be their cause, their nature and their character. Dermatology has properly to do with the integument and all that per tains to it, and moreover with all the varied causes that may disturb that organ. Thus the exanthema- tous and the numerous and diverse symptomatic eruptions, whether superficial or deep-seated, fugi- tive or persistent, are all entitled to a place in the group. One observation in support of this view is that practically it is often impossible to differentiate the several varieties of cutaneous inflammation which resemble one another, except through the causes which produce them. It is a notable fact that the same pathological state of the skin and the same lesions may be produced by several and even diverse causes, directly or remotely, entirely distinct from one another, as in the case of acne, acne rosacea and urticaria. Thus we note in practice that the lines separating the so- called idiopathic from the symptomatic diseases are far from being so sharp as is generally supposed. Authors of text-books and systems of dermatology would have us believe that the various diseases may all be arranged and satisfactorily classified, and that they may in all cases be readily differentiated from one another. While this undoubtedly holds true for the majority of cases, ample allowance must be made for atypical, irregular and anomalous forms of 6 disease, of which there occur, I am convinced, more examples than most authors are disposed to admit. Nor is sufficient latitude given in describing disease in general for complications which may occur, nor for the merging of pathological processes into one an- other. On this latter point, in particular, I would lay stress, especially as expressing certain anomalous forms of diseases. Mr. Hutchinson of London, was one of the first to direct attention to this point, of which we all I am sure have seen examples. As our knowledge of disease grows, so does the list of diseases increase, new affections, new varieties and combinations appearing and being described. To illustrate this observation we have but to look over treatises on dermatology published twenty-five years ago and to compare them with the works of to-day. The growth in this direction has been re- markable. Not only has the list increased, but it is still growing from year to year. Observations of this kind go to show, I think, that it is only a matter of time when every lesion that may occur on the integu- ment must be included in dermatology. There was a period, not many years ago, as most of us can re- member, when erysipelas was regarded as an exan- thema—an exanthematic fever, and as being there- fore altogether beyond the pale of dermatology. In those days that disease, it was said, was not a skin disease but a constitutional or a general disease, and that its relation to the skin was only incidental. How fallacious was this view, how slight our knowl- edge about this disease then, I need not more than refer to. I believe that before long certain other diseases will be recognized as being properly entitled to a place in cutaneous medicine which now are rele- gated elsewhere. Such a grouping should obtain, not with the view of magnifying the subject, but that the various similar and dissimilar diseases and the ex- pressions which they are capable of producing on the skin, may be brought together for purposes of study and comparison. 7 The time has arrived when we should endeavor to recognize not only the particular form of eruption, but what is more important, also, the cause which has produced it, upon which success in treatment may depend. Diseases of the skin must be studied from the standpoint of general medicine. It is not possible to comprehend the meaning of certain forms of inflammation of the skin without taking the broadest view of the subject. Thus if we are inclined to regard such diseases as dermatitis exfoliativa, pityriasis rubra, lichen ruber, dermatitis herpeti- formis, and the like as mere local cutaneous inflam- mations we fail to understand the significance of the symptoms. Symptoms and causes must be studied together. The former are elementary, and constitute the alphabet of dermatology, which it need not be stated must be learned. But eruptions in themselves, as mere forms of superficial inflammation, are by no means so important as the relation of the lesions to the causes. To express this idea more plainly, take the disease eczema as an instance. Here in some cases, as in neurotic eczemas, the discovery of the causes at work in producing the eruption is the key to the situation, without understanding which no success in the treatment will probably be obtained, and many other similar instances might be cited. Thus it happens that some diseases are practically uninfluenced by local treatment, and that not until we investigate their possible relations with the gen- eral economy do we appreciate their nature. The gen- eral practitioner, who has been trained in cutaneous medicine, has the opportunity of advancing dermatol- ogy quite as much as the specialist, and his services in aiding the good work can not be dispensed with. Some of the best work latterly has been done by men who are not only accomplished dermatologists but equally distinguished general practitioners of medi- cine and surgery. We owe a great deal to such writers and teachers as Jonathan Hutchinson, 8 Paget, Stephen Mackenzie, Fagge, Pye-Smith, Robert Liveing, Duckworth and McCall Anderson; The objective study of skin diseases is fascinating, and has without question its uses in more ways than one, but it is important that we take steps to advance beyond this elementary stage of knowledge, by at- tempting to recognize and understand the meaning of the local manifestation. It has been, and still is, too much the custom to study diseases of the skin in the light of pathological pictures, to name the local manifestation and to so label it as a disease. It is much easier to give the.disease a name and to label it than it is to comprehend the process at work. The former is comparatively unimportant for the patient, the latter a point upon which recovery may depend. The nature and meaning of the process in connection with the cutaneous symptoms has not received enough attention, and I believe this to be one reason why the treatment of many of these diseases in the past has been so notoriously unsatisfactory. At all events the relations of the cutaneous disturbance to other structures and to various states of the economy should be much more thoroughly investigated by dermatologists than is the present custom. To recognize any one disease, say syphilis, in its varied manifestations on the skin, requires familiar- ity with all other diseases with which it is liable to be confounded. Therefore, to be an accomplished diagnostician, one must be conversant with every form of eruption to which the skin is liable, includ- ing the not rare atypical and aberrant forms. In regarding only the well-known and clearly defined, obvious diseases of the skin as belonging to derma- tology, this branch of medicine is not only belittled, but the true meaning of many lesions on the skin is not appreciated. I would insist, therefore, that the manifold and varied changes that take place in the skin due, as we now know, to such a multitude of diverse causes, should be viewed as phases of cuta- neous medicine rather than as skin diseases. The 9 idea of this vast array of diseases being morbid enti- ties, for which the integument alone is accountable, must, in many cases at least, be abandoned in favor of the principles of general medicine. Allusion has been made to the fact that the same or similar lesions may be called forth by wholly dif- ferent causes. This also is a point to which attention has not been sufficiently directed by writers. As illustrative of the observation, the similarity in the eruptions of eczema and scabies may be referred to. Here the causes at work are different, but the result, as far as the skin is concerned, is much the same. On the other hand, the same cause may produce entirely different cutaneous lesions. A striking ex- ample illustrating this idea is found in dermatitis herpetiformis. Here the same cause at one period of the disease gives rise to an eruption resembling erythema multiforme, at another period to herpes, again to impetigo, and finally to pemphigus. We note thus that one process may occasion numerous distinct lesions, which individually may resemble what have been heretofore regarded as well-known distinct diseases. If we would study dermatology with the view of learning all that it can teach us, not only of the skin but of general medicine, we must look in the major- ity of cases beyond the mere eruption, valuable and important as this is in all cases as a guide to the pathological process at work. While, even in the case of local affections, it may not be necessary to look beyond the skin itself, we may nevertheless find in- teresting facts bearing on cause and pathology by searching within the economy. The cutaneous dis- turbance in many instances is distinctly indicative of some irritation or disorder in other regions, organs, structures or fluids of the body. That we are not able always to discover and to designate the causes, merely shows our ignorance. I am of the opinion that the relations of the skin to other parts and functions of the economy are at the present date 10 only partially understood, and that there are many points which will sooner or later be elucidated which will bring cutaneous medicine still closer to general medicine. Much, however, has been accomplished in this direction during the past twenty-five years, and I am pleased to add that a fair proportion of this good work has come from the labor of our countrymen. This brings me again to the question propounded at the beginning of these remarks, viz.: What are so-called skin diseases? The answer, I believe, has been given through the principles to which atten- tion has been called. It is simply this, that our conception of the scope of dermatology must be so widened as to include every pathological mani- festation which occurs in the integument, irrespective of the cause or the nature, from a practical stand- point. The great value and importance of dermatology is that it should teach us to know the nature of vari- ous processes, as they affect not only the skin but the whole economy. Dermatology should be for the phy- sician as a key with which the skin is made to reveal, in many instances at least, the nature of the process at work in the general system or in special organs, which without this aid might remain obscure. Strik- ing examples supporting this view are noted in syphi- lis and in leprosy, where the cutaneous manifestations are sometimes the only indication of the presence of these diseases in the body. The recognition of the nature of the cutaneous lesions is often of the greatest value in the general diagnosis. This observation applies pointedly in the case of the erythemata and certain general infectious diseases. While, therefore, not losing sight of the fact that some cutaneous diseases are strictly confined to the structure involved and have no other than a local significance, there are many in which the skin lesions must be regarded as being merely one set of a series of symptoms due to some special or general cause having its seat in other structures as well as in the 11 integument. The part that the nervous system plays in the production of varied diseases of the skin is, I am firmly convinced, immense. While its power and influence as a factor is well understood to-day, owing largely to the special writings of such observers as Eulenberg and Gruttmann, Bulkley, E. Long, Fox, Crocker, Schwimmer, Kopp and many others, I am of the opinion that its influence over the skin is at present far from being properly recognized. The nerves are avenues by which a multitude of diverse influences reach the skin. 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