# Pathogenesis of Chemical Leukoderma and Chemical‐Induced Vitiligo

## TL;DR

This review explains how certain chemicals can cause skin depigmentation disorders like leukoderma and vitiligo, focusing on rhododendrol and its impact on patients.

## Contribution

The paper clarifies the distinction between chemical leukoderma and chemical-induced vitiligo, emphasizing rhododendrol's role in outbreaks.

## Key findings

- Chemical leukoderma is temporary and reversible after chemical removal.
- Chemical-induced vitiligo involves irreversible depigmentation due to factors like autoimmunity.
- Rhododendrol is highlighted as a key chemical causing both conditions in large outbreaks.

## Abstract

Leukoderma/vitiligo is a serious pigmentary disorder that notably impairs the patient's quality of life. In particular, chemical leukoderma (CL)/vitiligo refers to acquired depigmentation of the skin induced by exposure to certain chemicals. In this review, the term “CL” is defined as the temporary, localized loss of pigmentation at the site of direct chemical exposure. When the causative chemical is removed, these skin patches undergo re‐pigmentation, indicating the restoration of melanocytes to their original condition. However, when the chemical‐induced skin depigmentation does not recover after the chemical is removed, or when de novo depigmented lesions emerge, it is classified as chemical‐induced vitiligo. This condition indicates that, even after chemical removal, the mature melanocytes cannot recover because of factors including, but not limited to, autoimmunity, stem cell depletion, and unknown factors. In this review, we summarized the latest pathological findings for each condition, focusing on rhododendrol, which is known to induce both phenotypes and cause an outbreak, which affected nearly 20,000 patients in Japan and other Asian countries.