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Research Letter

Validating a Novel Technique of Dermatoscopic Imaging or Sequential Comparison of Target Lesions in Vitiligo

Author Affiliation(s)

Introduction

Sequential dermatoscopy can be a handy tool to assess disease activity in vitiligo and hence guide management practices [ 1 ] . However, the small size of the contact plate of hand held dermatoscopes prevents the adequate capturing of images of larger patches in entirety. “Wide area digital dermoscopy” (WADD) and Video-WADD, are certain modifications used to acquire images of lentigo maligna and congenital melanocytic nevus [ 2 , 3 ] . This study aimed at devising a new method to acquire and store dermatoscopic images of vitiligo patches in entirety, which would facilitate easy sequential comparison.

Case Presentation

This prospective observational study was conducted at the outpatient department of a tertiary care center in India. Thirty patients of active vitiligo (defined as occurrence of new lesions or expansion of pre-existing lesions in the previous 6 weeks) were recruited. Two target lesions were identified in each patient and dermatoscopic assessment was performed at baseline and after 16 weeks of medical treatment resulting in 60 pairs of pre and post treatment photographs. The detailed methodology of patient recruitment and follow-up has previously been published [ 4 ] .

The reference points in the target lesion were marked according the markings on a clock, using different colored pens, akin to the technique used in Mohs micrographic surgery ( Figure 1 ) [ 5 ] . Dermatoscopic images were acquired from each quadrant, while maintaining an overlap of 10% between images. Both lesional and perilesional skin were included as marginal lesions are crucial in determining disease activity and repigmentation. Images were then merged to obtain a consolidated image using Adobe Photoshop software (Adobe Inc., version CS3).

The merged images were evaluated by 3 independent investigators at the end of the study (VK, AB, and AD) and graded on a Likert scale ( ). Consensus was said to be reached for each image if two or more investigators scored equal grades. Additionally, each investigator also scored the pair of pre- and post-treatment consolidated image of each patient. Cohn Kappa analysis was performed for two observers and Fleiss Kappa assessment was done for more than two observers, with level of agreement more than 0.6 considered as significant.

Amongst 120 consolidated images, consensus was not reached for one image, hence 119 images and 59 pairs were considered for analysis ( Table 1 ). Level of agreement between the three experts for consolidated mage analyses were acceptable (Cohn and Fleiss kappa value > 0.6).

Conclusions

The proposed technique has various advantages like ease of sequential comparison of dermatoscopic images post-treatment, more rapid assessment and reduced digital space usage in acquisition and storage of dermatoscopic images. Inter observer agreement was significant in majority of instances overall, denoting the reliability and reproducibility of this method in follow up of vitiligo.

However, this method currently has its limitations as well like difficulty in merging images larger than 6 cm, deterioration of quality due to variation in the orientation of the dermatoscope with respect to the anatomical position of the body and unprecedented technological limitations, which warranted manual merging of certain images.

Supplementary Information

References

  1. Dermatoscopic features of pigmentary diseases in ethnic skin Vinay Ankad BS. Indian Dermatol Online J.2021;12(1):24-33. CrossRef PubMed
  2. Wide area digital dermoscopy Dellatorre G, Gadens GA. J Am Acad Dermatol.2019;80(6):e153. CrossRef PubMed
  3. Video-based wide area digital dermoscopy Dellatorre G, Gadens GA, Polo Silveira L, Kose K, Marghoob AA. J Am Acad Dermatol.2022;87(4):e125-e126. CrossRef PubMed
  4. A prospective observational study to sequentially determine the dermoscopic features of vitiligo and its association with disease activity in patients on medical treatment Gupta P, Keshavamurthy V, Bishnoi A, Kumaran MS, Parsad D. Pigment Cell Melanoma Res.2023;36(1):33-41. CrossRef PubMed
  5. A novel way of mapping in Mohs micrographic surgery Xie Y, Bai J, Han L, Xia Y, Li L, Wan M. J Am Acad Dermatol.2021;85(3):e145-e146. CrossRef PubMed

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