Chemical leukoderma.

Chemical leukoderma is defined as an acquired, hypopigmented dermatosis that results from repeated cutaneous application of an agent that destroys epidermal melanocytes in genetically susceptible patients. Chemical leukoderma may develop both at the site of contact with the chemical as well as remotely from the exposure. Avoidance of the causative agent may lead to spontaneous repigmentation, but treatments commonly used in vitiligo, such as narrow-band ultraviolet B phototherapy, PUVA photchemotherapy, or topical immunosuppressants, often are necessary. We present a case of chemical leukoderma secondary to pyrethroid insecticides that has progressed despite avoidance of the agent for over ten years.