On the History of Classification in Dermatology.

Since the early days of cutaneous medicine, naming of the entities had remained a confusing subject. Earlier texts of all ancient civilisations are almost similar in this topic The Biblical controversy regarding the actual translational meaning of the original Hebrew term Zara 'at has become a centre of controversy amongst many research scholars of the medical history. Similar debate exists about the Ayurvedic term Kustha---- whether it meant leprosy or stood for a number of skin affliction is a matter of controversy. A scientific and rational classification system was, therefore needed. The process started with Galen and traversed a long path and ultimately with the eight orders classification system proposed by Robert Willan in the early part of the nineteenth century resolved the issue. This whole journey was eventful….almost all the great doyens of dermatology directly or indirectly contributed to this process. This overview will focus on the main such events of the medical history in nutshell.

“Want of classification in the first instance, and at a later period imperfect classifications, have greatly contributed to envelop in obscurity the history of cutaneous affections.”

What was known?

For proper diagnostic approach of diseases, lesions are classified into various groups and named in a scientific way. Similarly, skin lesions are also classified and are categorized under primary and secondary lesions.

Introduction

It was the third or may be the fourth quarter of the 18th century. Till then the subject of skin and its disorders was known by many names. Somebody called it “dermiatry,” other “dermology,” and still others “dermophily.” The issue needed a settlement and finally it cast aside the veil and was baptised as dermatology.[2] The debate regarding the nosology in dermatology is quite old. The controversy and debate continued for centuries. The impact of this confusion and controversy was immense. Not long ago, in 1898, Bulkley wrote in the beginning of the very first chapter of his famous book “Manual of Diseases of the Skin:”

Dermatology seems to many a difficult and uninviting field of study, and the great number of diseases described, together with the somewhat confusing nomenclature and classification often employed, have served to repel rather than attract practical medical man.[3]

Many regularly used but often confusing terms such as “lepra, psora, pemphigus, lupus” are some that haunted the field since ancient days. These not only baffled the medical community but also halted the progress of the subject as a whole due to the lack of uniformity in meaning and usefulness. To describe a lesion one needs to have a unanimous system of nomenclature lest no standardized and meaningful communication could be done among the fellow physicians across the medical world. Hence, a clear and unambiguous taxonomy was necessary. It finally evolved… but like Rome it was not built in a day, rather it took many centuries to take a final shape. In this article, we shall go through the story of evolution of classification in dermatology, although in brief.

The Ancient World and Classification

Classification per se is the scientific organization of a subject depending on various recognizable parameters and is a basic necessity in understanding, researching, practicing, and communicating the subject in an intelligent manner. The process of classification of cutaneous disorders started in the ancient world… both oriental and occidental. In India, important and significant skin diseases were grouped and described under individual diseases and skin diseases with lesser gravity were dealt under “kshudra roga” or “smaller disorder” category in the early texts of Ayurveda, namely, Charaka Samhita, Susruta Samhita, etc.[45]

The situation of nomenclature in the subject of skin and diseases in the Western world was also in a state of utter confusion. This may be made clear by taking an example of a few lines from book 13 of the Leviticus of old testament:[6]

“When a person has on the skin of his body a swelling, a rash, or a discoloration, and it develops into a scaly affection on the skin of his body, it shall be reported to Aaron the priest… If the hair on the affected part has turned white and the affection appears to be deeper than the skin of his body, it is a leprous affection….”

The word used for the above mentioned “leprosy” is Zara’at. However, was it “leprosy” or something else? Although this word has been translated by the translators of the Hebrew Bible to Greek as “leprosy” but the word does not stand for leprosy alone and instead represents many disorders starting from leprosy, vitiligo, psoriasis, postinflammatory leukoderma, Bejel and may be many more.[7]

This has happened with the words “psora, lichen, pemphigus…”; these terms were used and abused and stood more or less for a number of skin diseases with different related and unrelated natures. Many controversies erupted and engaged medical community for centuries to settle.

As far as the classification of diseases was concerned Hippocrates, the father of medicine propagated the philosophical idea of “etiological classification” by dividing disorders into local and constitutional.[8] In the history of Western Medical Science Galen of Pergamon (AD133–200) is considered as the second historical medical man after Imhotep of Egypt who lived during the period King Zosar during 3000 BC.[9] His contribution in the classification system sowed the seed of “topographical system” of classification of cutaneous diseases. Galen was first to divided skin diseases as: (i) Diseases of the hairy parts, and (ii) diseases of the nonhairy parts.[10] This system influenced and remained in vogue till about mid-18th century. The Galenic medicine had remained the back bone of modern Western medicine till about the 18th or 19th century.

The ‘Dark Age’ and Thereafter

After the ancient medicine reached its zenith during the period of Celsus and Galen, it started declining from its past glory. In the history of medicine 4–14th century was considered as the dark period as not much significant development had happened. Pusey has rightly said: “The whole period from the 4th to 14th century is marked by a futile scholasticism that was scientifically unimportant”.[11] If we go through the history, another 100 years may be added to this dark horizon, though the era of Renaissance has already begun. The next century, i.e., 16th century is often called the “first century of the modern world.” The Renaissance reached its maturity during this period. The period saw the activity of old masters such as Leonardo da Vinci, Raphael, Michel Angelo, and many others. The activity some famous rising stars of this period like Copernicus, Cervantes, Galileo, Kepler, and Shakespeare were on their highest level.

In this historical background, Gerolamo Hieronymus Mercurialis (1530–1606) initiated a new era of medicine in relation to skin and diseases. His “De Morbis Cutaneis et Omnibus Corporis Humani Excrementis Tractaus” is considered as the first systematic textbook on diseases of the skin by Garrison and Morton in the medical bibliography of medical history.[12] Mecurialis followed the topographical classification but elaborated it further and grouped skin diseases under two headings: (i) The types of disease peculiar to scalp: There were five types of such diseases; defluvium, premature calvities, canties, alopecia, and ophiasis; and (ii) those common to the entire skin: These are basically of three types: Those involving color, those involving texture and bulk.[13]

As already mentioned, this classification is basically a topographical or morphological classification, and does not corroborate with the etiopathology. During this latter part of the Renaissance, the cutaneous medicine was on the way of modernization. It was badly in need of a simple but logical classification. François Boissier de Sauvage of Lyon tried to propagate an idea, but that was not very successful.[9]

During this period, Carolus Linnaeus (1707–1778) entirely changed the vision of the biological world. He noted that symmetry existed among different living organisms and a group formed on the basis of these features distinguished it from the others; hence, if one knows the basic feature of a group the nature of its members could be predicted in a formula manner. This Linnaean system influenced our branch of medicine too. Charles Anne Lorry (1726–1783) of Paris followed the morphological path but tried to classify skin diseases in a Linnaean manner, but it became rather complicated one and therefore did not get much favor.[9] In the early 17th century, Riolanous tried to classify skin diseases according to the appearance of the lesions ignoring their topographical situation. This system became the foundation for the so called “artificial system” of classification in the later years.[8]

The Revolutionary Endeavor

The next major contribution came from Joseph Jacob Ritter von Plenck (1738–1807) of Vienna, Austria. He brought the skin disorders under 14 headings. His system considered external symptoms as the basis of classification. Plenck in the year 1776 proposed a classification system in his 128 page Latin octavo “Doctrina de Morbis Cutaneis.” His classification was based mainly on clinical morphology. He arranged the then known 115 skin diseases in to 14 classes and the whole thing was a one leaf affair [Figure 1]. This is the first time when terms such as macule, papule, vesicle, crusts were used as a heading under which all other diseases were grouped. First time in the history almost all diseases of the skin known during that period fitted in a simpler 14 heads.[14] Hence, he broke away from the path of 1500-year-old Galenic tradition of classifying in hairy-nonhairy way. However, his method was not perfect. Two of the classes namely ulcer and insect bite were based on etiology and other two classes nail disorders and hair disorders were anatomic, not morphologic. Hence, the system required further refinement.

Figure 1

Classification of cutaneous disorders in “Doctrina de Morbis Cutaneis” by Joseph Jacob Plenck[19]

The New Era Begins…

Almost two decades elapsed after the Plenck's publication. Robert Willan (1757–1812) was working incessantly on dermatology at Carey Street Public Dispensary in London. He recognized the worth of Plenck's work. The credit of providing the modern classification goes to him. Robert Willan, the British Physician, is considered by some authorities like Holubar and Wallach as the pioneer of the present-day dermatology.[2] The publication of his “On Cutaneous Diseases” in 1808 is considered as the beginning of the modern dermatology.

Practically, the present dermatological science starts with him.[15] His idea of classifying skin diseases was mainly based on the line of taxonomical arrangements propagated by Carl Linnaeus for the botanical and animal kingdom and influenced by the work of Plenck. He first recognized seven orders that were further subdivided into genera, species, and varieties. In 1798, he published his first order in a paper cover naming Papulae. Moreover, in 1808, he published his authoritative work “On Cutaneous Diseases Vol. I.” Compiling all the first four orders with 34 copper-engraved water color figures. This is the first time when a dermatology text was accompanied by colored illustrations. He thereafter fell ill and moved to Madeira hoping to recover. But he did not recover and died at the age of 55 on April 7, 1812. He could not complete his work on other four orders. That was subsequently completed and published as a book entitled “A Practical Synopsis on Cutaneous Diseases” by another doyen of dermatology, a friend and pupil of Willan, Thomas Bateman in 1813.[16] Robert Willan retained 6 of the 14 classes of Plenck and added another 2 [Figure 2]. Willan was the first to recognize 10 basic lesions in dermatology and named them which we use even now.

Figure 2

Classification of skin diseases in eight orders by Willan[20]

During the same period another new and innovative way of classifying dermatological disorder was evolving in France. A famous hospital l’Hopital Saint Louis was established by King Henry the IV in 1607 at Paris. Dermatology was started as specialty there in 1801. Jean Louis Alibert (1768–1837) was appointed as hospital chief there in 1801. In 1817 his work on classification of medical disorders were published as Noslogie naturelle. It was based on botanical analogy that was propagated by his master Pinel and Sydenham. His “Arbre des dermatoses” or the “tree of dermatoses” is a pictorial representation of his classification system [Figure 3]. The bark of the tree trunk represented epidermis and dermis, diseases were called lichens and mycoses.[17] The system was very much complicated, even his own colleagues of hospital St. Louis like Beitt, Cazenave, Schedel abandoned this in favor of more rational and simplistic Willan system.[18]

Figure 3

Alibert's “Arbre des dermatoses”[21]

The journey of classification of dermatological disorders has almost reached its final stage. This time it was the turn of Vienna to become the seat of the history. Ferdinand Hebra (1816–1880) was the man who finally explained the whole morphological system in light of pathologic anatomy. This surpassed all other classification, as this classification was no more a mere morphologic or macroscopic, it was based on the view of the lesion as well as within the lesion.

Ferdinand Karl Franz Schwarzmann Ritter von Hebra was born on 7th September in Brno, Moravia. He graduated from the University of Vienne in 1841. He was greatly influenced by the pathologic anatomy propounded by the great master Rokitansky. At very young age he published his famous “Atlas der Hautkrankheiten.” His second work “Lehrbuch” was on the pathology of the skin. This for the first time separated primary and secondary lesions and for the first time distribution of the lesions was considered for the diagnosis of a disease. Habra's path breaking works on the “pathologic-anatomic classification” and distribution of lesion and diagnosis opened a new horizon; the influence of Viennese school gradually spreaded to the United States and an altogether new era has begun.[14]

Epilogue

Classification has remained a long term quandary in the history of cutaneous medicine. For centuries in the history of dermatology understanding a skin disease by its name was a matter of great dilemma. For example, the word “leprosy” would stand for leprosy, vitiligo, psoriasis, or any other skin disease of unrelated connotations. Can anyone imagine a clear scientific communication about a disease among the member of the medical community without a proper nomenclature? This issue was settled with the formation of an unambiguous classification.

Thus, the journey of resolving the issue of taxonomy and nososlogy that started with Galen, the first grandmaster of Western medicine entered the new era with the Willianist method and finally completed with the establishment of modern dermatology headed by Hebra and assisted by other Viennese authorities like Moritz Kaposi.

Let us remember and pay tribute to our great teachers for they have made it easy for us to study, research, write, and communicate our subject with our fellow dermatologists and physicians of all other medical and scientific faculties all over the globe in an easy, clear, and comprehensible way.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

What is new?

The classification and nomenclature that we use today is a history of a long journey that traversed the path of debates and controversies

The contribution and effort of the great masters of yesteryears has cleared various confusions about the terminology of disorders of skin

The classification has made communication and understanding among the physicians and scientists undisputed and clear.