It is important to identify the nature of the border of a vitiligo lesion to ascertain the activity of the disease. Ascertaining disease stability is an important prerequisite before subjecting the patient to surgical management. Detection of an amelanotic lesion with a sharply demarcated border (ASDB) under Wood lamp is considered stable. Unstable, active vitiligo lesions are associated with hypomelanotic appearance with poorly defined borders (HPDB) [ 1 ] . However, Wood’s lamp requires a dark room and is difficult to use in busy outpatient practice.
Loss of melanin in vitiligo is seen clearly with a 470-nm blue light source from a multispectral dermoscope (DermLite DLII, multispectral; 3Gen, San Juan Capistrano, CA). Melanin absorption is highest in the ultraviolet spectrum and decreases toward a higher wavelength. Blue light from the dermoscope has a wavelength closer to the absorption peak of melanin [ 2 ] and is useful in delineating ASDB in stable vitiligo better than white-light dermoscopy ( Figure 1 ). HPDB seen in unstable vitiligo does not show this sharp delineation ( Figure 2 ). Blue light increases the contrast between lesions retaining melanin and areas of melanin loss, thus is useful for differentiating stable from unstable vitiligo.
Figure 1 .
Vitiligo; stable lesion. (A) White-light and (B) blue-light dermoscopy (×10). Blue light (470 nm) delineates amelanotic vitiligo with the sharply demarcated border better than white-light dermoscopy.
Figure 2 .
Vitiligo; unstable lesion. (A) White-light and (b) blue-light dermoscopy (×10). Blue light (470 nm) does not delineate hypomelanotic vitiligo with the poorly defined border.
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