HX23 Illuminating the skin: the enduring legacy of the wood lamp in dermatology

Abstract The Wood lamp was developed by Robert William Wood, an American physicist, in 1903. Since then it has remained a key tool in the dermatologist’s armamentarium. Wood exploited ultraviolet (UV) radiation, initially, to photograph human body parts. Wood – reported to be quite the showman – demonstrated to unwitting audience members how false teeth remained black under UV radiation, in contrast to the fluorescence of white teeth. In 1925, two French physicians, Margot and Deveze, realized the potential of the Wood lamp in dermatology, specifically regarding its role in numerous dermatoses. Margot and Deveze used the Wood lamp to study fungal infections, where the infections display the classical greenish fluorescence. The Wood lamp quickly became fundamental to clinical dermatology by providing a noninvasive method for detecting a wide range of skin conditions. The lamp emits longwave UV radiation (365 nm), causing different substances in the skin to fluoresce in distinct patterns, which can offer key diagnostic insights not visible under normal light conditions. The Wood lamp plays a crucial role in diagnosing pigmentary disorders such as vitiligo, where depigmented areas lack fluorescence, helping to assess skin involvement in the condition. Porphyrias can also be detected with the Wood lamp, where a distinctive red or purple fluorescence is noted under UV radiation. The lamp can also identify subtle changes in UV-damaged skin, such as those seen in actinic keratosis. Unfortunately, over time the utility of the Wood lamp has decreased in day-to-day practice with newer, more advanced diagnostic tools becoming more prevalent in everyday practice. However, the importance of the Wood lamp should not be overlooked within a dermatologist’s toolkit. Its low cost, ease of use and noninvasive nature make it especially useful in resource-limited settings. In teaching environments, it helps students and residents develop their diagnostic skills, providing another outlook for examining skin pathologies where the dermatoscope does not deliver. The wide scope and diversity of dermatology, along with the push for more inclusive training, should prompt dermatologists to consider the variety of skin conditions they may face, especially pigmentary disorders in skin of colour. In 2021, 18% of the population in England and Wales identified as a Black, Asian, mixed or other ethnic group, emphasizing the diagnostic challenges dermatologists may encounter without adequate training and appropriate tools. Therefore, ensuring the continued relevance of the Wood lamp and its ongoing use in clinical settings cannot be understated. The lamp’s simplicity, affordability and effectiveness solidify its place as a foundation in dermatological diagnostics and should equally form an integral place in a dermatologist’s clinic toolbox.