ロザシアにおけるデモデックスの検出：標準化された皮膚表面生検対紫外線ダーモスコピー

Demodex mites are believed to contribute to the pathogenesis of both rosacea and demodicosis. While standardized skin surface biopsy (SSSB) remains the gold standard for detecting Demodex density, it is invasive and time-consuming. Ultraviolet (UV) dermoscopy, a non-invasive technique that visualizes fluorescent structures, may offer a rapid alternative for identifying Demodex proliferation. To investigate the relationship between Demodex folliculorum (D. folliculorum) and Demodex brevis (D.brevis) counts obtained by SSSB and fluorescent dots detected under UV dermoscopy, and to evaluate the diagnostic value of these findings in rosacea and demodicosis.

Fifty-four patients with rosacea or demodicosis were evaluated using both UV dermoscopy and SSSB from the same facial region. Orange and bright blue fluorescent dots were recorded dermoscopically, and mite density and species were quantified via SSSB. Correlation analyses and ROC curve analysis were performed to assess diagnostic performance.

A significant positive correlation was found between total Demodex count and bright blue fluorescent dots (r = 0.343, p = 0.013), but not with orange dots (r = -0.065, p = 0.649). Only D. folliculorum showed significant correlation with blue and total fluorescent dots. ROC analysis identified >11 bright blue dots as the optimal threshold for predicting Demodex positivity, with a sensitivity of 82.1% and specificity of 71.4% (AUC = 0.793, p = 0.003).

Bright blue fluorescent dots observed under UV dermoscopy significantly correlate with Demodex density, particularly D. folliculorum. A threshold of >11 blue dots demonstrated good diagnostic accuracy and may serve as a practical, non-invasive alternative or adjunct to SSSB in clinical settings. Orange fluorescence was not associated with Demodex density and likely reflects unrelated sebaceous or microbial activity.