According to PodiatryNetwork, brown spots, or pigmented lesions, on top of feet are normally moles and freckles. However, they should always be observed and inspected because of the possibility of deadly pigmented lesions, such as malignant melanoma.
Malignant melanoma lesions are typically brown, blue or black, but they can also be mostly red or even white. The color of malignant melanoma pigment lesions is typically a mix of hues instead of one solid color, according to Food Health Facts. PodiatryNetwork states that the color of malignant melanoma skin lesions is "usually not uniform." Neurofibromatosis, a disease affecting the growth and development of nerve cell tissues, is another possible cause for brown pigmented skin lesions.