A colorimeter can detect change in color in vitiligo lesions after 1 month of narrow band ultra violet B (Nb-UVB) treatment before the change is clinically apparent, according to study findings published in the Journal of Cosmetic Dermatology.
Investigators aimed to determine whether the colorimeter and point counting technique are objective methods for monitoring changes in vitiligo lesions during treatment with Nb-UVB.
Participants received Nb-UVB treatment 3 times per week for 6 months. Each patient had 2 vitiligo lesions assessed for size using the point counting technique at the beginning of the treatment and every 4 weeks until the end of the study. Assessment of lesion color was conducted with the Dermacatch (Colorix), a visible-spectrum colorimeter that measures degree of color and melanin index (MI), before treatment and every 4 weeks for 6 months.
The study included 20 patients (13 women), aged 7 to 52 years (mean, 24.55 ± 16.03 years). Among the cohort, 8 patients had skin type III, 10 patients had skin type IV, and 2 patients had skin type V.
After 1 month of Nb-UVB treatment, 4 lesions had a marked increase in MI measurements inside the periphery, and 15 lesions had an increase in the center of the lesion. The area surrounding 11 lesions showed an increase in MI, and the perilesional area around 29 lesions had no change.
After 4 months, 38 lesions had an increased MI inside the periphery and center compared with pre-treatment measurements. The perilesional area in 30 lesions had an increased MI, 8 lesions had no changes, and 2 lesions had a decrease in MI. After 6 months, the 30 lesions still had increased MI in the perilesional area, 6 lesions were unchanged, and 4 lesions had a decreased MI.
Regarding the point counting technique for lesion size, the response increased with time, the researchers observed. At the study’s end, 1 lesion had a moderate response, 2 lesions showed good response, and 33 lesions had an excellent response. Also, 4 lesions increased in size, which indicated increased disease activity.
The researchers noted that the small sample size is a limitation to their findings.
“Dermacatch (colorimeter) was a reliable and objective tool to detect changes in the first period of treatment even before it was clinically apparent, which gives us hope for it to be used as a prognostic tool,” stated the investigators. “Point counting method was accurate and its results matched with that of Dermacatch, but it is time-consuming and hard to apply when monitoring many lesions.”
Tawfik NZ, Anbar MT, Atwa MA. Assessment of changes in color and size of vitiligo lesions during treatment with narrow band ultraviolet B. J Cosmet Dermatol. Published online November 21, 2021. doi:10.1111/jocd.14625