Wood's Light
Wood's Light
Wood’s Light
Wood’s light, also known as a Wood’s lamp, is a simple and effective method to diagnose specific dermatosis including cutaneous fungal, bacterial infections, and pigmentary disorders. It emits long-wave ultraviolet (UV) light, specifically in the range of 320-400 nm, with a peak at 365 nm. This type of light causes certain substances to fluoresce, making it useful for diagnosing various skin conditions.
key features and dermoscope usage:
1- Fluorescence:
- Certain fungal and bacterial infections can fluoresce under Wood’s light. For example, some species of dermatophytes (fungal infections) emit a characteristic yellow-green fluorescence.
- Bacterial infections like erythrasma caused by Corynebacterium minutissimum can show a coral-red fluorescence.
2- Pigmentary Disorders:
- Vitiligo: Areas of depigmentation will appear bright white under Wood’s light.
- Hyperpigmentation disorders can show different fluorescence compared to surrounding skin, aiding in diagnosis.
3- Skin Lesions:
- Differentiating between types of skin lesions, such as distinguishing between vitiligo and other hypopigmented lesions.
4- Scalp and Hair Examination:
- Detection of fungal infections of the scalp (tinea capitis) which may fluoresce under UV light.
- Identification of some hair shaft abnormalities.
5- Porphyria:
- Diagnosis of certain types of porphyria, a group of disorders related to the buildup of natural chemicals that produce porphyrin in the body. Porphyrins can fluoresce under Wood’s light
key features and dermoscope usage:
1- Procedure:
- Preparation:
- The examination room is darkened to enhance the visibility of fluorescence.
- The skin or scalp area of interest is cleaned to remove any cosmetics or topical medications that might interfere with the results.
- Examination:
- The Wood’s light is held a few centimeters away from the skin.
- The dermatologist observes the skin for any fluorescence or changes in appearance.
2- Limitations:
False Positives/Negatives: Certain substances like lotions, creams, or even lint on the skin can fluoresce, potentially leading to false positives or negatives.
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