Contact dermatitis: a historical perspective.

Contact dermatitis is a common skin condition that can have a considerable impact on patient quality of life and function. Historically, contact dermatitis has played a significant role in the evolution of dermatology as the understanding of a relationship between environmental exposure and specific skin disease became more widely accepted. Reports about this relationship can be found throughout the history of humanity, thousands of years ago. The Egyptians were perhaps the first to document this relationship in ancient history, and documentation has also been found in several other cultures and nations such as the Chinese, Indians, Europeans, and American colonizers. The patch test emerged over a century ago and has remained a powerful tool for diagnosing and directing patients. This paper provides historical and curious facts about contact dermatitis.

Allergic contact dermatitis.

Allergic contact dermatitis is one of the most important dermatologic disorders worldwide - it can cause significant morbidity and decreased quality of life, as well as having major economic implications and loss of vocational productivity. Patch testing is the most important discovery in allergic contact dermatitis and the best diagnostic modality to date; the thin-layer rapid- use epicutaneous (TRUE) test is a more recent patch test development which has improved the convenience and feasibility of the test. The future of allergic contact dermatitis is bright as we continue to learn more about the science of the disorder, as well as ways to improve diagnosis and patient care. Furthermore, it is important to remember, in this global age, that cooperation between health care providers worldwide is essential.

Patch testing: facts and controversies.

The German dermatologist, Josef Jadassohn (1863-1936), first presented the results of his innovative patch-testing technique in 1895. The safety and efficacy of this diagnostic tool has stood the test of time and is still the gold standard for the diagnosis of allergic contact dermatitis (ACD). Since its discovery, much effort has been put into standardization and optimization of allergens, vehicles, and concentrations of patch-test materials; in procedures of its application; and in reading and scoring of test reactions--all contributing to the development of an accurate, reliable, and safe test with a high reproducibility of its results. Even this seemingly carved-in-stone practice, which has been used for nearly 120 years, has been questioned and challenged, engendering debates, disagreements, and controversies, which show no signs of coming to an end. Almost every step of the procedure has provoked discussions and controversies:

Contact dermatitis: facts and controversies.

The history of contact dermatitis (CD) is inseparable from the history of the patch test, and the patch test is inseparable from the pioneer in the field, Josef Jadassohn (1860-1936). Despite the fact that we have been diagnosing, treating, and investigating the condition for more than 100 years, there are still many unsolved questions and controversies, which show no signs of coming to an end in the foreseeable future. This contribution reviews and highlights some of the disagreements and discrepancies associated with CD. For example: • What is the real sensitizer in balsam of Peru, one of the most common allergens, and what, if any, is the value of a low-balsam diet? • Is benzalkonium chloride, which has well-known and undisputed irritant properties, a contact allergen as well? • Is cocamidopropyl betaine (CABP) a common contact allergen and what is the actual sensitizer in CABP allergy the molecule itself, or impurities, or intermediaries in its synthesis? • How can the significant differences in the prevalence of sensitization of formaldehyde (FA, a common cause of contact allergy) between the United States (8%-9%) and Europe (2%-3%) be explained? • What is the relationship between formaldehyde releasers (FRs) allergy and an FA allergy? Should we recommend that FA-allergic patients also avoid FRs, and, if so, to what extent? • What is the true frequency of lanolin allergy? This issue remains enigmatic despite the expenditure of thousands of dollars and the innumerable hours spent investigating this subject. • What is the basis behind the so-called "lanolin paradox"? This label was coined in 1996 and is still a matter of controversy. • Is there such a thing as systemic CD from nickel, and, if so, to what extent? Is there a cross-reactivity or concomitant sensitization between nickel and cobalt?These are some of the controversial problems discussed. We have selected the ones that we consider to be of special interest and importance to the practicing dermatologist.

Historical perspective on the use of visual grading scales in evaluating skin irritation and sensitization.

Visual assessment of skin reactions has long been used to evaluate the safety of chemicals and preparations that contact the skin, and to meet regulatory requirements. This article reviews the history of visual grading scales, and the results of investigations into the reliability of the method. Some examples are provided to illustrate the diverse array of protocols that use visual scoring to evaluate skin irritation. Furthermore, as bioengineering methods are developed that can quantitate certain aspects of skin irritant and sensitization reactions, it is important to consider whether such measures should supplement or replace visual assessment. Examples of investigations comparing the outcomes of studies that use visual scoring and those that use bioengineering methods are discussed. These examples provide little evidence that bioengineering measures provide an improvement in overall quality in comparison with current testing methods that rely on visual assessment. In addition, such measuring techniques can add considerably to the complexity of testing protocols. When benefits and cost are weighed in the balance, the visual assessment scales popularized by Draize and others remain an effective, practical method of evaluation.

The continuing rise of contact dermatitis, Part 1: The academic discipline.

This article describes the history and development of contact dermatitis as an academic discipline, from early observations documented in ancient Egypt and Greece, to the current medical specialization we know today. Given its essential role in clinical diagnosis, the history of patch testing is also discussed, including the pioneering work of Städeler, von Hebra, Jadassohn, and others. The historical development of some international societies for contact dermatitis is provided, along with some discussion on bibliometric performance in this field. Overall, it can be seen that from humble beginnings, contact dermatitis is now thriving as a specialized field in clinical dermatology.

[Patch testing: historical aspects]. / L'historique des patch-tests.

This article reviews the key points in the history of patch testing, which spans more than a century, starting with the first description of the method by J. Jadassohn in 1895. Special attention is paid to the contribution of French schools in this field, which led to the foundation of the Groupe d'études et de recherches en dermato-allergologie (GERDA).