1.1 Introduction
Contact dermatitis, an inflammatory skin reaction to direct contact with noxious agents in the environment, was most probably recognized as an entity even in ancient times, since it must have accompanied mankind throughout history. Early recorded reports include Pliny the Younger who, in the first century a . d ., noticed that some individuals experienced severe itching when cutting pine trees. A review of the ancient literature could provide dozens of similar, mostly anecdotal, examples, and some are cited in modern textbooks, monographs, and papers.
It is interesting to note that the presence of idiosyncrasy was suspected in some cases of contact dermatitis reported in the nineteenth century, many decades before the discovery of allergy by von Pirquet. For instance, in 1829, Dakin, describing Rhus dermatitis, observed that some people suffered from the disease, whereas others did not. He therefore posed the question: Can it be possible that some peculiar structure of the cuticule or rete mucosum constitutes the idiosyncrasy?
The history of contact dermatitis in the twentieth century is indistinguishable from the history of patch testing, which is considered the main tool for unmasking the causative chemical culprits. Nevertheless, starting in the early 1980s, additional tests (within the scope of patch testing) have been introduced, such as the open test, the semi-open test, the repeated open application test (ROAT) and its variants, referred to as use tests. Moreover, prick testing, which has been underestimated for decades in dermato-allergology, has gained popularity, as an investigatory tool for immediate contact hypersensitivity.
1.2 Historical Aspects of Patch Testing
Historical aspects of patch testing are reviewed by Foussereau []. A selection of important forward steps has been made for this short survey.
1.2.1 The Pre-Jadassohn Period
During the seventeenth, eighteenth, and nineteenth centuries [], some researchers occasionally reproduced contact dermatitis by applying the responsible agent (chemical, plant, etc.) to intact skin. Most of the observations are anecdotal, but some deserve special attention.
In 1847, Stdeler [].
In 1884, Neisser [] reviewed a series of eight cases of iodoform dermatitis triggered by a specific influence. Neisser wrote that it was a matter of idiosyncrasy, dermatitis being elicited in these cases by iodoform application. The symptoms were similar to those subsequent to the application of mercurial derivatives, and a spread of the lesions that was much wider than the application site was a common feature to both instances.
In retrospect, this presentation can be considered an important link between casuistical writings of older times and a more scientifically orientated approach of skin reactions provoked by contactants. It was a half-hidden event that heralded a new era, which blossomed at the end of the nineteenth century.
1.2.2 Josef Jadassohn, the Father of Patch Testing in Dermatology
Josef Jadassohn (Fig. ].
Fig. 1.1
Josef Jadassohn (18631936) (used with kind permission from the Institut fr Geschichte der Medizin der Universitt Wien)
As recorded by Sulzberger in 1940 in his classic textbook [], the key message of Jadassohns paper was the fact that he recognized the process of delayed hypersensitivity to simple chemicals:
In his original publication, Jadassohn describes the following two occurrences: A syphilitic patient received an injection of a mercurial preparation and developed a mercurial dermatitis which involved all parts of the skin except a small, sharply demarcated area. It was found that the spared area was the site previously occupied by a mercury plaster which had been applied in the treatment of a boil.
In a second observation, a patient who had received an injection of a mercurial preparation developed an acute eczematous dermatitis which was confined to the exact sites to which gray ointment (Hg) had been previously applied in the treatment of pediculosis pubis. In this patient, the subsequent application of a patch test (Funktionelle Hautprfung) with gray ointment to unaffected skin sites produced an eczematous reaction consisting of a severe erythematous and bullous dermatitis.
When put together, those two observations reflect a double-winged discovery: the local elicitation of a mercury reaction and the local elicitation of refractoriness to reaction.
Concerning the technical aspects of the Funktionelle Hautprfung , the methodology was quite simple: gray mercury ointment was applied on the skin of the upper extensor part of the left arm and covered by a 5-cm2 piece of tape for 24 h. Many comments can be made at this point: (1) from the beginning, the patch test appears as a closed or occlusive testing technique, (2) the size of the patch test material is large (2.32.3 cm) compared to the current available materials, (3) the amount of ointment applied is not mentioned (the technique is therefore considered as qualitative), and (4) the duration of the application is limited in the present case to 24 h.
It should be remembered that soon after developing the patch test, Jadassohn was appointed as the Professor of Dermatology (1896) at the University of Bern (Switzerland) where he stayed for several years, before coming back (in 1917) to his native Silesia, in Breslau again. One of his major accomplishments there was the observation of a specific anergy in patients suffering from sarcoidosis or Hodgkins disease, for example.