This photograph demonstrates the hyperpigmented, brownish, velvety lesions of acanthosis nigricans. This skin condition may occur in skin folds such as the axilla (armpit - pictured here), neck, and other areas. In adults, it may be associated with hormonal problems, internal malignancy, obesity, and drugs.

This photograph demonstrates brownish, hyperpigmented, velvety plaques overlying the joints of the hands (metacarpal and interphalangeal joints).

People with neurofibromatosis often have more than 6 light brown spots (cafe-au-lait spots) larger than 1.5 centimeters. This is a picture of a giant cafe-au-lait spot on a person with neurofibromatosis.

The white spots on this person's face have resulted from drug-induced vitiligo. Loss of melanin, the primary skin pigment, occasionally occurs as a result of medications, as is the case with this individual. The typical vitiligo lesion is flat (macular) and depigmented, but maintains the normal skin texture.

This is a picture of vitiligo on the face. Complete loss of melanin, the primary skin pigment, occurs for unknown reasons. The resulting lesions are white in comparison to the surrounding skin. Vitiligo may occur in the same areas on both sides of the face (symmetrically) or it may be patchy (asymmetrical). The typical vitiligo lesion is flat (macular) and depigmented, but maintains the normal skin texture. The dark areas around the eyes are this person's normal skin color.

Cutis marmorata is a common phenomenon in newborn infants. It consists of alternating areas of dilated and constricted blood vessels, which gives the skin a red and white marbled appearance. It is most obvious when the skin is cool.

A halo nevus occurs when the body develops an immune response to the pigment cells around a nevus. The pigment disappears and the area becomes white. Often in the process, the nevus itself disappears, leaving a circular white spot (macula).