Utility of Blue Light in Dermoscopy for Diagnosing Stable Lesions in Vitiligo

Citation: Nirmal B. Utility of blue light in dermoscopy for diagnosing stable lesions in vitiligo. Dermatol Pract Concept. 2021;11(1):e2021141. DOI: https://doi.org/10.5826/dpc.1101a141

Accepted: September 19, 2020; Published: January 29, 2021

Copyright: ©2021 Nirmal. This is an open-access article distributed under the terms of the Creative Commons Attribution License BY-NC-4.0, which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original author and source are credited.

Funding: None.

Competing interests: The author has no conflicts of interest to disclose.

Authorship: The author takes responsibility for this publication.

Corresponding author: Balakrishnan Nirmal, MD, Department of Dermatology, Christian Medical College, Vellore, India. Email: nimu2swash@yahoo.co.in

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.