UVF Dermoscopy Performs Best Alongside Polarized Light Examination in Scabies Detection

Ultraviolet-induced fluorescence (UVF) enhances scabies detection in patients with both fair and dark skin, according to a study published in the Australasian Journal of Dermatology.¹

According to study authors Errichetti et al, it performs best alongside polarized light examination in this context.

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Background and Methods

Dermoscopy has enhanced the diagnostic accuracy of scabies, enabling clinicians to identify mites, burrows, and other characteristic findings more effectively than traditional methods, such as naked-eye examination or adhesive tape tests.²

However, certain limitations persist, particularly in diagnosing scabies in populations with darker skin types, where dermoscopic contrast can be challenging.³

This multicenter, observational retrospective study aimed to evaluate the diagnostic accuracy of polarized and UVF dermoscopy across varying skin tones. The study included 97 lesions from 43 patients diagnosed with scabies through microscopic examination or typical clinical findings and was conducted across 7 dermatology centers in Italy, India, Nigeria, Gambia, and Poland.

High-quality dermoscopic images were captured at 10x magnification under both UVF and polarized light settings using the DermLite DL5 device. Two independent investigators evaluated the images for hallmark scabietic findings, such as burrows, mites, scabietic eggs, mite feces, and wake-shaped scales.

Findings

UVF dermoscopy demonstrated a higher detection rate for burrows (96.9%) compared to conventional dermoscopy (82.5%). This advantage was statistically significant.

Conventional dermoscopy had a marginally higher detection rate for mites (68.0%) than UVF dermoscopy (53.6%), though the difference was not statistically significant.

UVF dermoscopy significantly outperformed conventional methods in identifying green dot signs (41.2% vs. 0%) and scabietic eggs (15.5% vs. 2.1%). Conversely, conventional dermoscopy was superior for detecting gray or gray-brown lines indicative of mite feces (13.4% vs. 0%).

For patients with lighter phototypes, UVF dermoscopy showed improved detection rates for burrows (98.2% vs. 92.9%) and green dots (62.5% vs. 0%). Conventional dermoscopy was more effective for identifying mites (94.6% vs. 80.4%).

In darker phototypes, UVF dermoscopy had a significant advantage in detecting burrows (95.1% vs. 68.3%) and scabietic eggs (17.1% vs. 0%). The green dot sign was identified in 12.2% of cases under UVF dermoscopy but was undetectable via conventional methods.

Conclusions

Though the study may be limited by its retrospective design, these findings advocate for the broader integration of UVF dermoscopy into dermatological practice, particularly in resource-limited settings or populations with diverse skin tones, according to Errichetti et al.

"Our accuracy analysis supports the usefulness of UVF dermoscopy in the diagnosis of scabies, particularly to detect the burrow (serpiginous light blue tract),” according to study authors. "This is in line with previously reported studies and could be due to the better ability of UVF setting to highlight deeper epidermal findings (i.e., scabietic tunnel) and exclude interfering superficial scaling as a result of its scarce light reflection.”

Further studies with larger cohorts are warranted to refine diagnostic protocols and explore the full potential of UVF technology in managing scabies and other dermatoses.

References

1. Errichetti E, Plozner N, Enechukwu NA, et al. Dermoscopy of scabies: utility of polarised and ultraviolet-induced fluorescence examination in fair and dark skin. Australas J Dermatol. December 27, 2024. doi:10.1111/ajd.14406
2. Park JH, Kim CW, Kim SS. The diagnostic accuracy of dermoscopy for scabies. Ann Dermatol. 2012;24(2):194-199. doi:10.5021/ad.2012.24.2.194
3. Balak DMW, Rauwerdink D. Diagnosing scabies in a patient with skin of colour using the burrow ink test. Clin Exp Dermatol. 2024;49(12):1758-1759. doi:10.1093/ced/llae358