No. 4299.

JANUARY 20, 1906.

An AddressON

THE PRACTICAL DIAGNOSIS OF THEDISEASES OF THE SKIN.

Delivered before the West Kent Medico-Chirurgical Societyon Nov. 3rd, 1905,

BY WILLMOTT EVANS, M.D , B.S., B.SC. LOND.,F.R.C.S. ENG.,

SURGEON IN CHARGE OF THE DEPARTMENT FOR DISEASES OF THE

SKIN, ROYAL FREE HOSPITAL.

GENTLEMEN,-Among the many special departments intowhich the wide extent of our knowledge has ne,essitated thedivision of medicine there is surely none which has beenmore neglected by the great body of the profession thandermatology. This fact for long appeared to me strange, forthere is no other part of the body so open to observation asthe skin and therefore at first sight it might be imaginedthat a knowledge of its diseases would be readily attained.The examination of the ear or of the eye is beset withdifficulties and even the investigation of the organs of thechest depends on the correct interpretation of signsascertained by auscultation and percussion. When thereis inflammation of the lung, for instance, the physician canonly ascertain the fact by various physical signs ; the lungitself is hid from his view and nothing can be seen of thevarious stages of the inflammation-the dilatation of thevessels, the exudation from the capillaries, and the variousother phenomena which go to form the complex conditioncalled inflammation. With the skin, however, it is farotherwise. Here every stage of the process can be watched,spread out before the eyes. The dilatation of the vesselsand even of the capillaries. if extensive, is visible to thenaked eye or a hand lens. The exudation into the substanceof the skin can be readily felt, or should the exudate bepoured out near or on to the surface it may collect intovesicles, or obvious droplets, or flow away in a stream. If

suppuration should occur we are not dependent for the infor-mation on thermometric indications, for the pus can be seeneither pent up in pustules or as a free discharge on thesurface. When, too, resolution occurs we do not have totrust to doubtful physical signs, for we can see with our owneyes the diminution of the discharge ; we can see the con-traction of the vessels which were before dilated ; and ourknowledge of the return to health proceeds pari, passw withthe process itself. Therefore a knowledge of the diseases ofthe skin should apparently be more widespread and morecomplete than the knowledge of the diseases of any otherpart of the body. Yet all will, I think, agree that it is notso and the explanation of this is to be found, in my opinion,in the fact that in dermatology we have a plethora of in-formation which from its very fulness tends to overburdenthe mind.There are so many differences observable in the skin that

it is exceedingly difficult for those who have not devotedmuch attention to the subject to recognise that some of thedifferences are important and some of no moment. Toreturn to my former comparison. In the lungs we canrecognise during life but a few types of inflammation andwe are therefore obliged to include under one name severalconditions which we should perhaps be able to distinguishif we could see the morbid processes during life. In thecase of the skin many slight differences are readilynoticeable and so it has come to pass that the numberof diseases recognised in the skin is very great. Toexplain more clearly my meaning I will imagine the

position of the skin so modified that it becomes an in-

ternal organ. Let us suppose a large portion of the skin tobe folded inwards to form a sac, so that the former super-ficial surface looks inwards ; how many different diseasesshould we be able to recognise in it ? We should have varioussymptoms and perhaps a few physical signs ; the nature ofthe discharge from the mouth of the sac we are imaginingwould also assist us somewhat, but we should have little else,so that we should have to include under one name conditions

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essentially different, and this statement brings me naturally tothe second cause of the general lack of knowledge of thediseases of the skin. It is the multitude of names. There are fewskin diseases which have only one name ; most have at leasttwo and many have five or six names. Nay, more, the namesof many of the diseases of the skin consist of several words ;for instance, erythema induratum scrofulosorum, and thisincreases the difficulty of remembering the names. I amnot saJing that there is no excuse for this multiplicity andcomplexity of the names in dermatology. There is oftenample excuse or even reason, but the fact remains tt at thenomenclature is a. great deterrent to the tudy of the diseasesof the skin. Further, not only have many skin diseases twonames, but, what is worse, the same name, or two namesonly slightly different, may be applied to two totally distinctdiseases. For instance, pityriais rubra has nothing what-ever to do with pityriasis rubra pilaris. Again, in some

foreign countries-Germany, for instance-the generic nameherpes is applied to the ordinary ringworm of the scalp,tinea tonsurans, as it is called in this country, which, it ishardly necessary to say, has nothing to do with herpeszoster. It is clear, then, that there are many difficulties inthe way of a knowledge of dermatology, but they neednot deter anyone who really cares to undertake the study ofthe diseases of the skin.

It is possible sometimes to treat a condition successfully,even though no diagnosis has been made; yet this is the

exception, and as a general rule all satisfactory treatmentdepends on a correct diagnosis and thus I have chosen the

diagnosis of the diseases of the skin for my subject this

evening. Some diseases can be readily diagnosed. We canrecognise them at once from long lasting familiarity, evenas we recognise the face of a friend. Perhaps we cannotdescribe in exact terms the points on which the immediaterecognition is based, just as we may be absolutely sure ofthe identity of a man we know well, even though we maynot be able to say what are his distinctive features. As an

example of this I may mention leprosy ; a typical case of itmay be recognised at a distance of many feet by those whoare familiar with the disease. I do not want you to imaginefor a moment that I am suggesting that treatment should bebased on such a hasty diagnosis, for we should never proceedto treatment until the diagnosis is as certain as we can makeit, but I wish to impress upon you the fact that familiaritywith a disease may make it recognisable at a distance. Small-pox is another good example of a disease often recognisableat sight. The first point of importance in the diagnosis of adisease of the skin is to identify the primary lesion. Whereshould this be sought ? In nearly all cases it is at the

margin of a patch of the eruption that we shall find leastmodified the primary lesion with which the disease starts.In the centre of a patch the skin lesion will have progressedand will represent a later stage. It may then be in a more

fully developed condition or retrogression may have com-menced and partial recovery may have occurred, and so thecondition may be unrecognisable. Papules may have mergedto form patches, vesicles may have burst, and scratchingor rubbing may have assisted in modifying the original con-dition ; while at the periphery a fresh intact example of theprimary lesion may have recently appeared.When the primary lesion has been identified, whether

papule, vesicle, or pustule, or whatever it may be, then itsother characters must be examined. Say that it is a papule,is its outline round or angular? Is its top flat, pointed, orrounded? Does its colour disappear on pressure or is it

permanent ? When points such as these have been settled wehave gone far towards diagnosing the disease. For to follow

up the example already given, the angular, flat-toppedpapules of lichen planus can hardly be mistaken when

typical papules are seen. The next point to remember indiagnosis is that one definite condition may have manymodes of formation. To tale an instance, pigmentation.It may in the first place be natural, as in the skin of a negro ;in this case the pigment is situated in the lining cells of theMalpighian la‘ er of the epidermis. Pigment is present inthe skin of white people, and this pigment, small in amountthough it is at the most, may be completely absent. If

congenitally so the case is one of albinisin, or the pigmentmay be removed in parts by disease ; thus we find patchesof excessively white skin in leucoderma, or vitiligo as itis sometimes called. In the latter case the surroundingskin is generally darker, giving the appearance of thepigment having been swept from the patch and heaped upround the margin. In the macular variety of true leprosy

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very similar patches may occur, and the two conditions are toften confused, especially in countries such as India, where ileprosy is not rare, leucoderma being mistaken for leprosy. tAn important distinction and one easily applied is this-in z

the leprotic patches there is anaesthesia, while in the ccolourless areas of leucoderma sensation is unaffected. a

Increase of pigment is, however, much more common than ia loss of the colouring matter of the skin. This increase i

may be due to minute capillary hxmorrhages, as in purpura, 7or an ordinary skin lesion usually unpigmented may leave s

much pigment behind it, as, for instance, urticaria vpigmentosa. The growth of a fungus in the epidermis may clead to the formation of dark patches, as in tinea versicoloror chromophytosis. Lastly, it must not be forgotten that a

pigmentation of the skin may be the effect of drugs, t

perhaps used locally, as may occur after the application of a Imustard plaster, or the drug may have been administered B

internally, as with arsenic and silver. Lastly, pigment may e

be the essential part of a new growth, as in melanotic sar- i

coma. Thus we see that it is not sufficient to recognise the sexistence of deficient or excessive pigmentation ; the modeof onset, the situation, and the course of the lesion must be aobserved before a true diagnosis is possible. s

Let us take another example. A true vesicle is a small televation of a part of the epidermis inclosing a clear serous efluid and vesicles differ chiefly one from another in the (

thickness of the epithelial layer forming the roof. A i" button " of mollnscum oontagiosum to the naked eye looks <not unlike a vesicle and its umbilication resembles closely ithe similar condition in the vesicular stage of small-pox, 1but a section shows that the swelling is solid and is <

caused by a modification of the epithelium. Scales are imasses of epithelial cells ready to be cast off ; they (

may b3 scanty so as only to be seen with a lens, 1or they may be present in enormous quantities, as ]

in dermatitis exfoliativa. Scaliness and cracking of thepalms o the hands may be merely the result of an

eczematous inflammation brought about by prolonged andrepeated immersion of the hands in water, as in washerwomenand bottle washers, and in this case both hands will probablybe affected. A very similar condition is produced bysyphilis and the affection on one hand may in this case

precede the affection of the other by several weeks. Ulti-mately, if left untreated, the soles of the feet are liable alsoto be attacked. A not dissimilar thickening and cracking ofthe palms and soles may be caused by the prolongedadministration of arsenic.

This is a convenient place to speak of the mingling ofvarious primary lesions. For instance, erythema is thename applied typically to a mere reddening of the skin dueto dilatation of the cutaneous capillaries, but we mayreasonably apply the name erythema to allied conditions inwhich the pathological process has gone beyond, sometimesfar beyond, mere erythema, for papules, rings, vesicles,nodules, and bullae may be seen as in erythema multiforme.Nodules may be derived from various sources. For instance,in neuro-fibromatosis or Recklinghausen’s disease the nodulesare swellings on the nerves and their branches. In othercases nodules in the skin may be malignant in nature or theymay be formed from scars, as in keloid.Another important point that has to be considered in the

diagnosis of a disease of the skin is the arrangement of theskin lesion. We may take as an example ringed eruptions.Naturally, perhaps, an idea of a tinea arises at first sight ofa ringed eruption and some of the best marked rings are dueto a trichophyton but many other skin diseases may appearas rings. There is a great tendency for syphilitic manifesta-tions, especially in the secondary stage, to be circinate incharacter ; and rings mav also appear in the congenital formof the disease. Psoriasis may also be mentioned as veryprone to assume the ringed form. In fact, all diseases whichspread centrifugally tend to clear in the centre and so formrings, and this is especially likely to occur in disease due tothe local presence of a micro-organism. When rings of anyetiology meet serpiginous forms appear but they very rarely,if ever, overlap.The situation of the disease is also of very great import-

ance and value in diagnosis. Familiar to you all are the

rough, scaly patches on the elbows and knees in psoriasis.In this case the situation is sometimes of itself sufficient todecide a doubtful diagnosis. A preference for the samesituations is to be seen also in a much rarer disease,xanthoma, but in this the patches are not scaly but areyellow in colour. Another instance of situation assisting in

the diagnosis is to be found in the pustules on the handsin scabies. It is, however, with the distribution of nervesthat we derive perhaps the greatest assistance, as in herpeszoster, where the relation of the distribution of thedisease to the area of distribution of a nerve assists ns inarriving at a diagnosi-, whether the nerve involved is anintercostal or, as in the less common variety, the nerveis the supra-orbital or a branch of the cervical plexus.The fact that an eruption is seen at the margin of the hairyscalp naturally suggests that it has spread from the scalpwhere it has arisen, and in this way it is often possible todiagnose seborrhceic dermatitis of the forehead.The location of the redness in acne rosacea is of itself

almost enough to settle the diagnosis, which is confirmed bythe presence of numerous papulo-pustules. In xerodermapigmentomm the area affected-namely, the face and arms-will suffice to show that exposed surfaces are the partsaffected and therefore the exposure has had a causal con-nexion with the disease ; in this case the agent has beensunlight which has given rise to the morbid condition.Sometimes the structure in the skin which is involved canassist in the diagnosis. When we see a crop of pustulesand every pustule pierced by a hair, we may be sure

that the condition is a folliculitis, in all probabilityset up by an external irritant. When we meet with aneruption of a very unusual type and we are told that itis of recent origin, the thought should always arise thatthe eruption may possibly be due to some poison,internal or external. The iodides and bromides are thegreatest offenders in this respect. The presence of an unusualeruption with the coexistence of " fits should alwayssuggest a bromide eruption. This is an example of a

diagnosis depending on collateral circumstances apparentlyunconnected with the eruption. Another example which Imay mention was seen in a general vesicular eruptionoccurring in a chi’.d five years old within a fortnight of thevaccination of a baby sister. The character of the vesiclessupported the reasonable diagnosis that a generalised vac-cinia was present.The possibility of a lesion of the skin being factitious

should always be borne in mind. The chief characteristicsof these are as follows : they usually occur in girls or youngwomen, though I have seen a troublesome case in a youngman ; secondly, if the patient is right-handed the lesionsare most likely to be found on the left forearm and theright leg ; and thirdly, the lesions are generally longerin the long axis of the limb and often have square ends.The effect of treatment is sometimes of immense value indiagnosis, especially in suspected syphilitic lesions, but timewill not permit of my going fully into this branch of thesubject.

In the skin we have an additional agent in diagnosis whichcan hardly be employed in any other part of the body. Irefer to the microscopical examination of a portion of thelesion during life. A small portion of the skin can easily beremoved under local anaesthesia ; it can be cut and stained

’ and a microscopical examination may at once suffice to settlea diagnosis otherwise very doubtful. This process is some-

7 times called a biopsy.I have endeavoured in this paper to point out some of the

’ more important points on which a diagnosis of a disease of the skin may be based. Nothing but practice will give real. familiarity with skin lesions and enable diagnosis to be easy,z but however well acquainted one may be with the morbid appearances of the skin yet cases will not infrequently occurr where the dermatologist is unable to give an exact diagnosis.’

Repeated observation of the same case may ultimately enable a diagnosis to be made, but a diagnosis is not always possible.

THE UNIVERSITY OF SHEFFIELD.-The councilof the University has appointed Dr. Louis Cobbett, M.A.,M.D. Cantab., F.R.C.S. Eng., Professor of Pathology in theUniversity. Dr. Cobbett held the coveted John LucasWalker Studentship at Cambridge, in which capacity asdemonstrator of pathology in the University he had theadvantage of working under the late Professor Roy andthe late Professor Kanthack successively. His work inbacteriology includes some valuable research into the

organisms causing diphtheria, while recently he has beenengaged upon the study of the relations of human andbovine tuberculosis on behalf of the Royal Commission onTuberculosis.