Skin lesions refer to any variation in skin color or texture anywhere on the body. Some skin lesions are present at birth, such as moles, freckles, or birthmarks. Others are acquired over time, such as acne, warts, allergies, sunburn, or abrasions. Most skin lesions are harmless. However, it is important to keep an eye on them because they can change over time, which may be indicative of a serious problem. For example, one pigmented lesion that can occur on the foot and lower extremity is malignant melanoma.

A condition called actinic keratosis is another cancer-causing lesion that can occur on the feet. It is most commonly found in sun-exposed areas, such as the top of the foot. Treatment consists of freezing the lesions with liquid nitrogen or sharp excision.

Kaposi's Sarcoma is another cancerous lesion that may appear on the soles of the feet of people with HIV infection or AIDS. Karposi's Sarcoma lesions are irregular in shape and have a purplish, reddish, or bluish-black appearance. They tend to spread and form large plaques or become nodular. The nodular lesions have a firm rubbery appearance.