Wood's Lamp Examination: Clinical Applications

Overview / Definition Wood's lamp examination, also known as ultraviolet (UV) light examination, is a diagnostic technique that employs a specific wavelength of UV light (365 nm) to examine the skin. This method is particularly useful for identifying fungal infections, bacterial infections, and certain skin disorders that exhibit characteristic fluorescence. Epidemiology Wood's lamp examination is widely used in various clinical settings, particularly in dermatology and pediatrics. It is especially beneficial in the diagnosis of: Fungal infections such as tinea capitis. Vitiligo, which may show enhanced contrast under UV light. Porphyria, which can fluoresce under UV light. The prevalence of conditions observed via Wood's lamp varies by population and geographic location, with some fungal infections being more common in specific areas. Pathophysiology / Mechanism Wood's lamp emits long-wave UV light, which causes certain substances in the skin or hair to emit visible light. This phenomenon occurs due to the excitation of fluorescent compounds, such as: Fungal elements: Many dermatophytes produce metabolites that fluoresce. Pigmentary disorders: Conditions like vitiligo have underlying changes in melanocytes that can be visualized. Porphyrins: Elevated levels in conditions like porphyria cause characteristic fluorescence. Understanding the mechanisms behind fluorescence aids in recognizing specific conditions during examination. Clinical Presentation During a Wood's lamp examination, the clinician will observe the skin under the UV light. Key clinical presentations include: Tinea Capitis: May fluoresce yellow-green. Vitiligo: Appears bright white, indicating the absence of pigment. Porphyria Cutanea Tarda: Can show a reddish-orange fluorescence. Physical signs may vary based on the underlying condition, and careful observation is essential. Diagnosis / Workup Wood's lamp examination is often performed as part of a comprehensive dermatologic evaluation. The procedure