The Scope of Dermatology.

Chairman’s Address read In Section of Dermatologyand 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 FROMTHE JOURNAL OF THE AMERICAN MEDICAL ASSOCIATION,

FEBRUARY 17, 18%.

CHICAGO;PRINTED AT THE OFFICE OF THE JOURNAL OP THE ASSOCIATION.

1894.

THE SCOPE OF DERMATOLOGY.

LOUIS A. DUHRING, M.D.

On the occasion of the last annual meeting of thisSection of the Association, the honor to preside overthe deliberations of thepresent meeting was conferredupon me. It affords me pleasure to greet you as mem-bers of the Association, and especially as attendantsupon the work of this Section, whose importance I be-lieve must be more fully recognized by the professionwitheach succeeding year. Before taking up the origi-nal papers to be presented for reading and discussionI would ask your attentionfor a few moments to con-sider of what dermatology actually consists. Thesubject, I believe, will not prove uninteresting norwithout profit practically. Let me propound thequestions, What are so-called skin diseases, and whatis their nature? Which diseases are entitled to bedesignated “ 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 thoughtappear easy, and so they seemed to the writermany years ago, when thoroughly imbued with thespirit of local pathology, as taught by his former andrespected master Hebra, it was deemed all sufficientto study cutaneous diseases purely objectively. Butthe questions propounded upon investigation reallybecame difficult problems, especially with the lightthat has been thrown upon dermatology by compar-atively recent studies. The field, viewed in everydirection, has become immensely enlarged, and theamount of work done, both clinical and patho-

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logical, has been remarkable. I believe, however,that a satisfactory solution of these problems maybe found. The questions that immediately confrontus are, shall the term, “skin disease,” continue to beused in its ancient sense? Shall the affections of theskin be looked upon as morbid entities, as diseaseswhole and complete in themselves and confined tothe 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 byWillan in England, when the list of diseases wassmall and knowledge of them meagre. I have nodesire 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 ofthe skin was both judicious and successful. But theimportant questions of etiology and pathology werethen for most diseases not at all understood. Verylittle was known on those subjects. The origin ofmost disease was regarded as “obscure.” The factsthat a mite was the sole cause of scabies, and thatringworm was due to a fungus were still unknown,while the observation that almost all the drugs inthe Pharmacopoeia are capable of producing dis-order of the skin was not even suspected. Affectionsof the skin were regarded mainly objectively, andwere studied much as a model or a picture might beviewed. Beyond the actual expression on the integ-ument they were not closely investigated; the causeswere regarded as obscure: and this mode of study-ing them has held good through decades, up to almostthe present date. This method is in no way to becriticized so far as it goes, but by itself and withoutthe assistance of general pathology, it is far toorestricted to meet the requirements of existing knowl-

edge. It fails to recognize the important fact thatthe integument is a part of the whole organism, andtherefore is subject to the great laws of generalpathology, and that diseases affecting the integu-ment are not only to be studied as localized areas ofdisease, but also in their relation to the system atlarge.

For the majority of cases no laws can be laid downtending 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 iswise not to press such questions too closely in ourendeavor to determine these intricate problems.Local pathology, interesting and satisfactory as it isas a study, must never be permitted to outweigh thegeneral process, to which in many instances we mustlook as the fons et origo of the disease. That somediseases are strictly local in all their aspects will bedenied by no one, but it is practically often difficultto 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 ofthe many and often obscure reflex affections.

On the other hand, it is not difficult with ourknowledge of to-day, to give examples of some trueskin diseases. Notably among these may be men-tioned the local parasitic affections,the inflammationsdue to numerous external causes, as for example therhus plant and certain of the hypertrophic, atrophicand neoplastic diseases, such as callositas, clavus,cornu, molluscum fibrosum and molluscum epithe-liale. In these affections, and in some others thatmight be cited, as far as our knowledge extends, theskin is the only organ of the body invaded at anytime in the course of the disease. But while thisholds true for a considerable number, there arestill many that are in reality widespread diseases,the skin being only one of the organs involved bythe process.

As instances of such may be cited the so-called

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exanthemata, as well as other eruptive fevers, theeruptions 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 theskin, and whether it does not also involve otherstructures of the body, as for example the epithe-lium generally, as in pityriasis rubra and derma-titis exfoliativa. Another group would compriseherpes zoster, pemphigus and the like, where thenervous structures, central or peripheral, are in somewav at fault.

Still another class consists of diseases which, whileeminently skin diseases, are in some cases at leastdependent upon certain peculiar states of the economyfor their existence, as a type of which psoriasis maybe given. As an example of the effect of the state ofthe system at large upon this disease, I may cite thecase of an old gentleman, an experienced physician,whose chronic and inveterate psoriasis had resistedall manner of internal and local treatment, but whoupon going to sea immediately experienced relief anda rapid diminution in all the symptoms, so that inless than a fortnight he had practically recoveredfrom a disease which had for a long period provedentirely intractable to our best remedies.

Another well-defined disease attacking the skin iseczema. While this is often a local affection, it mayalso be started into existence and kept up by seriousinternal derangements of the economy. In the lattercases it must be regarded in part at least as asymptomatic affection, as in the case of other symp-tomatic disorders, as urticaria; for with improve-ment of the digestive and assimilative functions ornervous 8}7 stem the eruption improves or disappears.These observations are particularly striking in thecase of infants and children.

But it is not so much my purpose to specify and todifferentiate the local from the general diseases

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affecting the skin, as it is to direct attention to whatI believe to be an important truth in medicine,namely, that many cutaneous lesions which havelong been and still are regarded as local skin dis-eases are really cutaneous expressions of certaingeneral pathological processes, due to varied causes.If this proposition, which might be elaborated, beaccepted as an accurate observation, it brings us tothe point I am desirous of establishing, namely, thatour ideas of dermatology should be greatly enlarged.I am firmly of the opinion that this branch of medi-cine should include all morbid manifestations thatappear on the skin, whatever may be their cause,their nature and their character. Dermatology hasproperly to do with the integument and all that pertains to it, and moreover with all the varied causesthat may disturb that organ. Thus the exanthema-tous and the numerous and diverse symptomaticeruptions, whether superficial or deep-seated, fugi-tive or persistent, are all entitled to a place in thegroup. One observation in support of this view isthat practically it is often impossible to differentiatethe several varieties of cutaneous inflammationwhich resemble one another, except through thecauses which produce them. It is a notable fact thatthe same pathological state of the skin and the samelesions may be produced by several and even diversecauses, directly or remotely, entirely distinct fromone another, as in the case of acne, acne rosacea andurticaria.

Thus we note in practice that the lines separatingthe so- called idiopathic from the symptomatic diseasesare far from being so sharp as is generally supposed.Authors of text-books and systems of dermatologywould have us believe that the various diseases mayall be arranged and satisfactorily classified, and thatthey may in all cases be readily differentiated fromone another. While this undoubtedly holds true forthe majority of cases, ample allowance must bemade for atypical, irregular and anomalous forms of

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disease, of which there occur, I am convinced, moreexamples than most authors are disposed to admit.Nor is sufficient latitude given in describing diseasein general for complications which may occur, norfor the merging of pathological processes into one an-other. On this latter point, in particular, I wouldlay stress, especially as expressing certain anomalousforms of diseases. Mr. Hutchinson of London, wasone of the first to direct attention to this point, ofwhich we all I am sure have seen examples.

As our knowledge of disease grows, so does the listof diseases increase, new affections, new varietiesand combinations appearing and being described.To illustrate this observation we have but to lookover treatises on dermatology published twenty-fiveyears ago and to compare them with the works ofto-day. The growth in this direction has been re-markable. Not only has the list increased, but it isstill growing from year to year. Observations of thiskind go to show, I think, that it is only a matter oftime when every lesion that may occur on the integu-ment must be included in dermatology. There wasa 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. Inthose days that disease, it was said, was not a skindisease but a constitutional or a general disease, andthat 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 thanrefer to. I believe that before long certain otherdiseases will be recognized as being properly entitledto a place in cutaneous medicine which now are rele-gated elsewhere. Such a grouping should obtain, notwith the view of magnifying the subject, but that thevarious similar and dissimilar diseases and the ex-pressions which they are capable of producing onthe skin, may be brought together for purposes ofstudy and comparison.

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The time has arrived when we should endeavor torecognize not only the particular form of eruption,but what is more important, also, the cause whichhas produced it, upon which success in treatmentmay depend. Diseases of the skin must be studiedfrom the standpoint of general medicine. It is notpossible to comprehend themeaning of certain formsof inflammation of the skin without taking thebroadest view of the subject. Thus if we are inclinedto 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 thesymptoms. Symptoms and causes must be studiedtogether. The former are elementary, and constitutethe alphabet of dermatology, which it need not bestated must be learned. But eruptions in themselves,as mere forms of superficial inflammation, are by nomeans so important as therelation of the lesions tothe causes. To express this idea more plainly, takethe disease eczema as an instance. Here in somecases, as in neurotic eczemas, the discovery of thecauses at work in producing the eruption is the keyto the situation, without understanding which nosuccess in the treatment will probably be obtained,and many other similar instances might be cited.Thus it happens that some diseases are practicallyuninfluenced by local treatment, and that not untilwe investigate their possible relations with the gen-eral economy do we appreciate their nature. The gen-eral practitioner, who has been trained in cutaneousmedicine, has the opportunity of advancing dermatol-ogy quite as much as the specialist, and his servicesin aiding the good work can not be dispensed with.Some of the best work latterly has been done by menwho are not only accomplished dermatologists butequally distinguished general practitioners of medi-cine and surgery. We owe a great deal to suchwriters and teachers as Jonathan Hutchinson,

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Paget, Stephen Mackenzie, Fagge, Pye-Smith, RobertLiveing, Duckworth and McCall Anderson;

The objective study of skin diseases is fascinating,and has without question its uses in more ways thanone, but it is important that we take steps to advancebeyond this elementary stage of knowledge, by at-tempting to recognize and understand the meaningof the local manifestation. It has been, and still is,too much the custom to study diseases of the skinin the light of pathological pictures, to name the localmanifestation and to so label it as a disease. It ismuch easier to give the.disease a name and to labelit than it is to comprehend the process at work. Theformer is comparatively unimportant for the patient,the latter a point upon which recovery may depend.The nature and meaning of the process in connectionwith the cutaneous symptoms has not receivedenough attention, and I believe this to be one reasonwhy the treatment of many of these diseases in thepast has been so notoriously unsatisfactory. At allevents the relations of the cutaneous disturbance toother structures and to various states of the economyshould be much more thoroughly investigated bydermatologists than is the present custom.

To recognize any one disease, say syphilis, in itsvaried manifestations on the skin, requires familiar-ity with all other diseases with which it is liable tobe confounded. Therefore, to be an accomplisheddiagnostician, one must be conversant with everyform of eruption to which the skin is liable, includ-ing the not rare atypical and aberrant forms. Inregarding 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 isnot appreciated. I would insist, therefore, that themanifold and varied changes that take place in theskin due, as we now know, to such a multitude ofdiverse causes, should be viewed as phases of cuta-neous medicine rather than as skin diseases. The

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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 favorof the principles of general medicine.

Allusion has been made to the fact that the sameor similar lesions may be called forth by wholly dif-ferent causes. This also is a point to which attentionhas not been sufficiently directed by writers. Asillustrative of the observation, the similarity in theeruptions 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 produceentirely different cutaneous lesions. A striking ex-ample illustrating this idea is found in dermatitisherpetiformis. Here the same cause at one periodof the disease gives rise to an eruption resemblingerythema multiforme, at another period to herpes,again to impetigo, and finally to pemphigus. Wenote thus that one process may occasion numerousdistinct lesions, which individually may resemblewhat have been heretofore regarded as well-knowndistinct diseases.

If we would study dermatology with the view oflearning all that it can teach us, not only of the skinbut of general medicine, we must look in the major-ity of cases beyond the mere eruption, valuable andimportant as this is in all cases as a guide to thepathological process at work. While, even in the caseof local affections, it may not be necessary to lookbeyond the skin itself, we may nevertheless find in-teresting facts bearing on cause and pathology bysearching within the economy. The cutaneous dis-turbance in many instances is distinctly indicativeof some irritation or disorder in other regions, organs,structures or fluids of the body. That we are notable always to discover and to designate the causes,merely shows our ignorance. I am of the opinionthat the relations of the skin to other parts andfunctions of the economy are at the present date

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only partially understood, and that there are manypoints which will sooner or later be elucidated whichwill bring cutaneous medicine still closer to generalmedicine. Much, however, has been accomplishedin this direction during the past twenty-five years,and I am pleased to add that a fair proportion ofthis good work has come from the labor of ourcountrymen.

This brings me again to the question propoundedat the beginning of these remarks, viz.: What areso-called skin diseases? The answer, I believe, hasbeen given through the principles to which atten-tion has been called. It is simply this, that ourconception of the scope of dermatology must beso widened as to include every pathological mani-festation which occurs in the integument, irrespectiveof the cause or the nature, from a practical stand-point. The great valueand importance of dermatologyis that it should teach us to know the nature of vari-ous processes, as they affect not only the skin but thewhole 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 processat 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 manifestationsare sometimes the only indication of the presence ofthese diseases in the body. The recognition of thenature of the cutaneous lesions is often of the greatestvalue in the general diagnosis. This observationapplies pointedly in the case of the erythemata andcertain general infectious diseases.

While, therefore, not losing sight of the fact thatsome cutaneous diseases are strictly confined to thestructure involved and have no other than a localsignificance, there are many in which the skin lesionsmust be regarded as being merely one set of a seriesof symptoms due to some special or general causehaving its seat in other structures as well as in the

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integument. The part that the nervous system playsin the production of varied diseases of the skin is, Iam firmly convinced, immense. While its power andinfluence as a factor is well understood to-day, owinglargely to the special writings of such observers asEulenberg and Gruttmann, Bulkley, E. Long, Fox,Crocker, Schwimmer, Kopp and many others, I am ofthe opinion that its influence over the skin is at presentfar from being properly recognized. The nerves areavenues by which a multitude of diverse influencesreach the skin. The future will, I feel sure, see thisparticular subject much more elaborated than it isto-day.

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