The spectrophotometrical analysis of rhododendrol‐induced leucoderma using a novel multispectral camera

Summary Background Many users in Japan of skin brightening/lightening cosmetics containing rhododendrol ( RD ) have developed leucoderma. Leucoderma appears on skin areas repeatedly treated with RD ‐containing cosmetics. RD ‐induced leucoderma ( RDIL ) presents different degrees of well‐defined hypopigmentation. It is crucial to determine the degree of hypopigmentation to differentiate RDIL from vitiligo vulgaris ( VV ). Objectives To quantitatively evaluate hypopigmentation of RDIL lesions and the recovery of pigmentation, and to compare the hypopigmentation with VV and normal skin. Materials and methods Sixteen cases of RDIL , nine cases of VV and 15 healthy controls were examined using a novel multispectral camera ( MSC ) that can simultaneously obtain the reflection intensity at 10‐nm wavelength intervals from 400 to 760 nm of the photographed area. ∆Absorbance was calculated by subtracting the log of reflection intensity of the target area from that of a white reflection standard. Results Most RDIL lesions showed lower ∆Absorbance than healthy skin and higher ∆Absorbance than VV lesions between 400 and 550 nm. Statistical comparison of the maximum ∆Absorbance from 420 to 460 nm (Max∆Absorbance) for VV , RDIL and control skin showed that the Max∆Absorbance of RDIL was significantly higher than that of VV and lower than that of control skin. The comparison of ∆Absorbance of the same sites in RDIL lesions between the initial visit and 6 months later showed significant improvement after 6 months. Conclusions These studies demonstrated quantitative changes in RDIL and its recovery phase and suggested the utility of a MSC in obtaining objective colour information of skin disorders.