The Proposed Categorization of Vitiligo Lesions on the Hands

Abstract

Vitiligo is a common depigmentation disorder characterized by patchy white macules. It has been reported that vitiligo lesions, particularly in exposed areas, such as the face and hands, cause severe psychological distress. Although the classification and outcome of facial vitiligo have been proposed, clinical analyses featuring hand vitiligo are very limited, irrespective of its severe psychological impact. In this study, we investigated hand lesions in nonsegmental vitiligo patients and found that the distribution of hand vitiligo was symmetric, whereas the dominant hand was more frequently affected. Moreover, our clustering analysis newly classified hand vitiligo lesions into four distinct subtypes (n = 140): focal/scattered (46.4%), distal digit (31.4%), universal (12.9%), and proximal digit (9.2%) and their clinical characteristics. The focal/scattered type is the most common subtype and exhibits a distinctive prevalence in pediatric cases. The distal digit type was suggested to be associated with smoking or the Koebner phenomenon. The universal type is a distinct subtype, with onset in older age and a poor response to treatment. The proximal digit type is the rarest subtype, with onset at a young age. In conclusion, these findings deepen our understanding of the heterogeneity of hand vitiligo and support the development of personalized treatment strategies.

Keywords: classification; clustering; distribution; hands; vitiligo.

FIGURE 1

140 cases of hand vitiligo patients were enrolled in this study. (a) The flowchart of enrolling patients in this study. (b) The dorsal hand was divided into 25 parts and assessed using an 11‐ point scale ranging from 0 (uninvolved) to 10 (entirely involved).

FIGURE 2

Distal digits were more affected in comparison to proximal areas. (a) The distribution patterns of vitiligo on hands were presented with a heat map. The cases with higher scores were indicated inside each hand. (b) Comparison of scores between distal, middle, and proximal digits. The scores for distal digits were significantly higher than those for proximal digits in the 1st‐4th digits. *p < 0.05, **p < 0.01, ***p < 0.001.

FIGURE 3

Although the distribution of hand vitiligo was symmetric, the dominant hand was more frequently affected. (a) A strong correlation was found between the scores for the right and the left hand. (R ² = 0.9319, p < 0.0001). (b) The scores for the right hand were significantly higher than those for the left hand (p < 0.0001). (c) 63.08% of cases showed higher scores in their dominant hand.

FIGURE 4

Relationship between smoking and digital vitiligo lesions and temporal progression of hand lesions. (a) The initial univariate analysis revealed that distal scores of smoking cases (n = 17) were significantly higher than those of non‐smoking cases (n = 56) (p = 0.0443). (b) In a subsequent analysis of covariance (ANCOVA) using variables selected by the least absolute shrinkage and selection operator (LASSO), disease duration remained a statistically significant predictor of the distal digit score (coefficient = 0.264, p = 0.00042). Other selected variables, including age, universal type distribution pattern (identified in subsequent cluster analysis), and involvement of other anatomical sites, did not show statistically significant associations. The model explained approximately 26.3% of the variance in distal digit scores (R ² = 0.263). (c) Upon stratification by age group (≥ 56 vs. < 56 years), a statistically significant association between smoking and the distal digit score was evident only in patients under 56 years of age. (d) Score changes in 86 cases during 2.3 years of average follow‐up. (e) The score for the digits tended to deteriorate compared to that for others, especially found in the left hand. *p < 0.05.

FIGURE 5

The results of cluster analysis presented as a heat map identified four distinct distribution patterns.