Which condition is characterized by the loss of pigmentation in certain areas of the skin?

The correct choice is vitiligo, as this condition is specifically characterized by the loss of pigmentation in distinct patches of skin. This occurs due to the destruction of melanocytes, the cells responsible for melanin production, leading to lighter areas where the skin has lost its color. Vitiligo can affect individuals of any skin type and may occur in various patterns on the body.

In contrast, melasma involves dark pigmentation, typically on the face, often related to hormonal changes or sun exposure, rather than a loss of pigmentation. Albinism is a genetic condition that results in little or no melanin production throughout the body, but it is not characterized by patchy areas of loss, as it affects the skin uniformly. Lentigo, on the other hand, refers to small, pigmented spots (often called age spots or liver spots) on sun-exposed areas of the skin, which indicates localized pigmentation rather than a loss of it. Thus, vitiligo uniquely describes the condition of losing pigmentation in specific regions of the skin.