Dermoscopy Combined with Wood Lamp: A Diagnostic Approach for Five Facial Pigmented Lesions

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Dermoscopy Combined with Wood Lamp: A Diagnostic Approach for Five Facial Pigmented Lesions

Facial pigmented lesions, including chloasma, nevus fusco-caeruleus zygomaticus, nevus of Ota, freckles, and Riehl melanosis, represent common dermatological challenges. These conditions often overlap in clinical presentation, complicating accurate diagnosis. Histopathological biopsies, though definitive, are invasive and impractical for patients seeking cosmetic solutions. This observational study evaluates the combined utility of dermoscopy and Wood lamp examinations as non-invasive diagnostic tools for differentiating these five facial pigmented lesions.

Study Design and Methodology
Conducted at the Affiliated Hospital of Xuzhou Medical University, this study enrolled 361 patients with facial pigmented lesions between January 2017 and July 2019. Ethical approval (No. XYFY2019-KL189) and patient consent for image use were obtained. The SK-3 dermoscopy (Beining Inc., Nanjing, China) utilized visible light with polarized magnification to visualize epidermal and superficial dermal structures. The Wood lamp (KN-9000B, Kernel, Xuzhou, China) emitted a 320–400 nm wavelength laser (peak: 365 nm) with an output power ≥3.0 mW/cm² to assess autofluorescence patterns. Patients underwent standardized imaging: lesions were cleaned, positioned 5 cm from the light source, and imaged sequentially under dermoscopy and Wood lamp.

Diagnostic Features of Individual Lesions

  1. Nevus Fusco-Caeruleus Zygomaticus
    Dermoscopy revealed pale brown globules in 85.2% (92/108) of cases. Wood lamp imaging highlighted blue-black spots contrasting sharply with adjacent normal skin. These features correlate with dermal melanocytosis, distinguishing it from epidermal pigmentation.

  2. Nevus of Ota
    Dermoscopic analysis showed a light brown homogeneous pattern in 86.7% (39/45) of lesions. Under Wood lamp, dark blue-brown patches were evident, reflecting deeper dermal melanocyte aggregation. The absence of vascular networks differentiated it from chloasma.

  3. Chloasma
    Dermoscopy identified a yellowish-brown homogeneous appearance in 92.9% (79/85) of cases, with visible capillary networks in 74.1% (63/85). Wood lamp findings varied: progressive chloasma exhibited subclinical pigmentation extending beyond visible borders, while stable chloasma showed congruent lesion areas under both modalities. This distinction aids in monitoring disease activity and guiding therapy.

  4. Freckles
    Dermoscopy demonstrated round or oval yellowish-brown globules in 94.9% (94/99) of patients. Wood lamp imaging accentuated lesion boundaries with deepened pigmentation and scattered black spots, consistent with epidermal melanin accumulation. The clarity of margins under Wood lamp distinguished freckles from other patchy lesions.

  5. Riehl Melanosis
    Dermoscopic evaluation revealed small grayish-brown blotches forming a pseudo-network in 95.8% (23/24) of cases. Wood lamp imaging displayed dark patches, correlating with mixed inflammatory and pigmentary changes in the superficial dermis. This combination helped differentiate Riehl melanosis from post-inflammatory hyperpigmentation.

Advantages of Combined Modalities
Dermoscopy provides magnified, real-time visualization of structural patterns, such as globules, networks, and vascularity. Wood lamp enhances diagnostic accuracy by highlighting pigment depth and subclinical involvement through autofluorescence. For example, in chloasma, Wood lamp detected subclinical pigmentation in progressive cases, guiding treatment intensity. Similarly, the blue-black contrast in nevus fusco-caeruleus zygomaticus under Wood lamp confirmed dermal involvement, ruling out superficial mimics.

Clinical and Practical Implications
The non-invasive nature of these tools is critical for cosmetic patients. Dermoscopy allows longitudinal tracking of lesion evolution, while Wood lamp aids in assessing treatment response. For instance, reduced subclinical pigmentation under Wood lamp may indicate therapeutic efficacy in chloasma. The study emphasizes standardized imaging protocols—consistent light intensity, patient positioning, and lesion selection—to minimize variability.

Limitations and Histopathological Correlation
Despite high diagnostic accuracy, the study acknowledges limitations. Dermoscopic patterns (e.g., homogeneous brown areas) lack specificity without Wood lamp corroboration. For example, early Riehl melanosis may mimic freckles dermoscopically, necessitating Wood lamp’s fluorescence to detect inflammatory components. Additionally, neither modality replaces histopathology for ambiguous cases. However, their combined use reduces unnecessary biopsies, particularly in cosmetically sensitive areas.

Conclusion
This study demonstrates that dermoscopy and Wood lamp synergistically enhance the diagnosis of facial pigmented lesions. Key dermoscopic features—such as globules, networks, and vascular patterns—complement Wood lamp’s ability to delineate pigment depth and subclinical spread. For conditions like chloasma, this combination informs disease staging and therapeutic planning. While histopathology remains the diagnostic gold standard, the integration of these non-invasive tools offers a practical, patient-friendly alternative for initial assessment and follow-up. Future studies could explore automated image analysis to standardize interpretations and expand applications to other pigmentary disorders.

doi.org/10.1097/CM9.0000000000001009

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