Final answer:
Oval or irregular patches of white skin lacking normal pigment are indicative of vitiligo, which occurs when melanocytes in certain skin areas stop producing melanin.
Step-by-step explanation:
Oval or irregular patches of white skin that do not have normal pigment are characteristics of vitiligo. Vitiligo leads to a loss of color in patches because melanocytes in certain areas cease to produce melanin, possibly due to an autoimmune reaction. By contrast, albinism is a genetic disorder caused by the inability of melanocytes to create melanin at all, leading to a lack of pigmentation in skin, hair, and eyes.