A Study on Applying Slide-Free Label-Free Harmonic Generation Microscopy For Noninvasive Assessment of Melasma Treatments With Histopathological Parameters

Ming-Liang Wei,Yuan-Ta Shih,Yi-Hua Liao,Wei-Hung Weng,Chi-Kuang Sun,Yi-Shuan Sheen

doi:10.1109/jstqe.2021.3069472

Abstract

Melasma, which is thought to be associated with hyperactivation of melanocytes, is a common hyperpigmentary skin disorder. To treat this skin disorder, dermatologists can benefit from in vivo information of cellular morphometrics to evaluate pathologies of melasma and effectiveness of treatments. To acquire this useful information, we applied the in vivo slide-free label-free harmonic generation microscopy (HGM) to retrieve real-time HGM images and subsequent critical histopathological parameters. These in vivo quantitative parameters included melanin mass density (MMD), melanocyte dendricity score (MDS), melanophage density (MPD), and thickness of dermal papilla zone (DPZ). The statistical results from 33 recruited Asian female melasma patients showed that MMD, MDS, and MPD in melasma lesions were significantly higher than those in the surrounding normal skin; by contrast, the DPZ was lower. After treatment, the MMD, MPD, and DPZ restored toward the normal level; however, we observed no significant change of MDS. Our study indicates that these parameters are able to serve as clinical indices to evaluate the histopathological characteristics of melasma patients and the effectiveness of treatments.

Highlights

M ELASMA, caused by hyperpigmentation of melanin and thought to be associated with hyperactivation of melanocytes, is a common hyperpigmentary skin disorder found frequently on both sides of the face
Skin aging has been demonstrated to be associated with flattening of the dermal-epidermal junction, so the thickness of dermal papilla zone (DPZ) is expected to decrease with age [16, 17]
The thickness of DPZ may be a meaningful parameter as an index for some skin disorders [19] such as melasma

Summary

Introduction

M ELASMA, caused by hyperpigmentation of melanin and thought to be associated with hyperactivation of melanocytes, is a common hyperpigmentary skin disorder found frequently on both sides of the face. Melasma is characterized by epidermal hyperpigmentation [3], increased number of melanocytes [3], modification on the extracellular matrix [4], and perivascular lymphohistiocytic infiltrates [5]. Kang et al [7] stated that 47 of 56 cases (84%) showed an increased number of melanocytes in melasma lesions. These ex vivo histopathological parameters of cellular morphometrics, including the number and dendricity of melanocytes, are considered to be critical parameters to determine the pathogenesis

Methods

Results

Conclusion