### Date : 2024-06-23 19:36
### Topic : Wood's Lamp Examination #medicine #dermatology #infectology
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### Wood's Lamp Examination Overview
**Wood's lamp examination** is a diagnostic tool used in dermatology to detect bacterial or fungal skin infections, pigmentary disorders, and other skin irregularities. The Wood's lamp emits long-wave ultraviolet (UV) light, which causes certain substances to fluoresce (glow) under its illumination.
### Purpose of the Wood's Lamp Examination
1. **Diagnose Infections:**
- **Fungal Infections:** Certain fungal species fluoresce under UV light.
- **Bacterial Infections:** Specific bacteria may show characteristic fluorescence.
2. **Identify Pigmentary Disorders:**
- **Vitiligo:** Areas of depigmentation appear starkly white.
- **Hyperpigmentation:** Differentiates between epidermal and dermal pigmentation.
3. **Detect Skin Irregularities:**
- **Erythrasma:** A bacterial infection that fluoresces coral-red.
- **Pseudomonas Infection:** Appears green under UV light.
### Procedure
**1. Preparation:**
- **Dark Environment:** The examination is performed in a dark room to enhance the visibility of fluorescence.
- **Patient Preparation:** The skin area to be examined should be clean and free from topical products like lotions or creams, which can interfere with the results.
**2. Application:**
- **Wood's Lamp Device:** A handheld lamp emitting UV light is used.
- **Examination:** The lamp is held about 4 to 5 inches away from the skin, and the examiner observes any fluorescence.
**3. Observations:**
- **Fluorescence:** The color and intensity of the fluorescence are noted.
- **Pattern and Distribution:** The pattern and distribution of the fluorescing areas are also observed.
### Interpretation of Results
**1. Infections:**
- **Fungal Infections:**
- **Microsporum spp.:** Greenish-yellow fluorescence (common in tinea capitis).
<Wood's Lamp Examination Findings of Tinea Capitis by Microsporum canis>
<Photo from: https://e-jmi.org/archive/detail/44?is_paper=y>
- **Bacterial Infections:**
- **Corynebacterium minutissimum:** Coral-red fluorescence (indicative of erythrasma).
- **Pseudomonas spp.:** Green fluorescence.
**2. Pigmentary Disorders:**
- **Vitiligo:** Areas appear bright white under the Wood's lamp, sharply contrasting with surrounding skin.
<Photo from: https://tangsclinical.com/the-woods-lamp-can-be-used-to-confirm-diagnosis-when-vitiligo-is-suspected/>
- **Epidermal Hyperpigmentation:** Enhanced contrast, appearing darker under UV light.
- **Dermal Hyperpigmentation:** Little to no change under UV light compared to normal light.
**3. Other Conditions:**
- **Porphyria:** Urine may show pink to red fluorescence.
- **Acne and Skin Oils:** Certain components of acne (e.g., Propionibacterium acnes) and skin oils can fluoresce orange-red.
### Example Case Study
**Patient Profile:**
- **Name:** Jee Hoon Ju
- **Age:** 25
- **Occupation:** Student
**Medical History:**
- Complaints of discolored patches on the face and neck, unsure if it’s a fungal infection or a pigmentary issue.
**Procedure:**
- **Wood's Lamp Examination:** Conducted in a dark room using a Wood's lamp.
- **Observations:**
- Patches on the neck fluoresce bright white, consistent with vitiligo.
- No greenish-yellow fluorescence, ruling out tinea versicolor.
**Diagnosis:** Based on the Wood's lamp examination, Jee Hoon Ju is diagnosed with vitiligo.
**Management:**
- **Education:** Provided information about vitiligo and potential treatment options.
- **Topical Treatments:** Prescribed topical corticosteroids to manage the condition.
- **Phototherapy:** Discussed as a potential treatment to restore pigmentation.
### Advantages and Limitations
**Advantages:**
- **Non-Invasive:** Safe and painless diagnostic tool.
- **Quick and Easy:** Provides immediate results.
- **Differentiation:** Helps distinguish between different types of skin conditions.
**Limitations:**
- **False Positives/Negatives:** Some substances may interfere with results, and not all pathogens fluoresce.
- **Limited to Surface:** Primarily effective for surface-level conditions; deeper skin issues may not be detected.
- **Skill Dependent:** Accurate interpretation requires experience and expertise.
### Conclusion
Wood's lamp examination is a valuable diagnostic tool in dermatology for identifying infections, pigmentary disorders, and other skin conditions. By observing the fluorescence of skin under UV light, healthcare providers can quickly and effectively diagnose and manage various dermatological issues. Proper preparation and skilled interpretation of results are essential for accurate diagnosis.