What are oval or irregular patches of white skin that lack normal pigment called?

The term for oval or irregular patches of white skin that lack normal pigment is vitiligo. This skin condition occurs when melanocytes, the cells responsible for producing skin pigment (melanin), are destroyed or stop functioning. As a result, affected areas lose their color, leading to the characteristic white patches. Vitiligo can vary in size and can appear on any part of the body, causing a contrast with the surrounding skin.

Leukoderma, while sometimes used interchangeably, generally refers to a broader category of skin conditions leading to depigmentation due to various causes, but it does not specifically identify the unique characteristics of vitiligo. Psoriasis is a different skin disorder associated with rapid skin cell turnover, leading to thick, red, scaly patches. Dermatitis refers to inflammation of the skin and can have various symptoms, but it does not specifically involve the absence of pigment as seen in vitiligo. Understanding these distinctions helps clarify why vitiligo is the most appropriate answer in this context.