Wood’s Lamp Examination | Observing fluorescence distribution over large areas

1. What is Wood’s Lamp Examination?

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A Wood’s lamp is an examination that shines a special light in the UV spectrum onto the skin to observe the distribution of fluorescence not visible to the naked eye.

Porphyrins produced by acne bacteria and Malassezia-related lesions can appear fluorescent under a Wood’s lamp.¹ While a Wood’s lamp views a wide area at a glance, UV Dermoscopy magnifies and observes individual pores.

2. Why is Wood’s Lamp Examination Performed?

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2.1 Checking the distribution of porphyrin fluorescence

Acne bacteria produce porphyrin during their metabolic processes. When illuminated by Wood’s lamp, this porphyrin can appear as orange to red fluorescence.² By observing the distribution of porphyrin fluorescence, the degree of pore occlusion can be indirectly assessed.

2.2 Supportive findings for Malassezia-related lesions

Bright fluorescence may be visible under a Wood’s lamp in some tinea versicolor lesions.³ However, since the color and intensity can vary depending on the device and imaging conditions, the cause cannot be confirmed by fluorescence alone.¹

3. Our Clinical Application

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We utilize Wood’s lamp examination at various stages of clinical assessment.

1. Moisturizer Matching: We recommend moisturizers based on the distribution of porphyrin fluorescence. Detailed information can be found on the MD Cream page.
2. Acne diagnosis: In cases of severe folliculitis, the distribution of porphyrin fluorescence is used as a reference to identify the cause. For more details, see the Acne, Isotinon, and Aklief pages.
3. Selection Between Elidel and Protopic: When prescribing non-steroidal anti-inflammatory ointments, we prioritize Elidel when acne is present or pores are occluded, and Protopic when these conditions are absent.
4. Supportive Findings for Skin Infections: We check for the presence of fluorescence in certain tinea versicolor lesions.

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References

1. Dyer JM, Foy VM. Revealing The Unseen: A Review of Wood’s Lamp in Dermatology. J Clin Aesthet Dermatol. 2022;15(6):25-30.
2. Shu M, Kuo S, Wang Y, et al. Porphyrin metabolisms in human skin commensal Propionibacterium acnes bacteria: potential application to monitor human radiation risk. Curr Med Chem. 2013;20(4):562-568.
3. Labedz N, Navarrete-Dechent C, Kubisiak-Rzepczyk H, et al. Pityriasis Versicolor-A Narrative Review on the Diagnosis and Management. Life (Basel). 2023;13(10):2097.