A change in skin spot color from brown to red could be the result of a variety of factors, including aging, sun exposure or development of a melanoma. While potentially dangerous skin spots usually darken and change from brown to black, any color change could be an indication of underlying cancer, according to Everyday Health. Conditions that specifically involve the formation of red spots include cherry hemangioma, squamous cell carcinomas and basal cell carcinomas.
The change in a pre-existing spot often occurs due to fluctuations in melanin, the main pigment of the skin. Said fluctuations include skin lightening, which may explain a change in a brownish spot to a lighter, reddish one. Cherry hemangioma, defined by Everyday Health as being a common condition involving the appearance of small, red spots, occurs due to overgrowth of blood vessels under the skin. Cherry hemangioma is frequently found in the elderly and does not indicate cancer.
Both squamous cell and basal cell carcinomas, however, do indicate cancer. Squamous cell carcinomas are characterized by reddish nodules, either flat or cone-shaped, while basal cell carcinomas redden and bleed, according to Live Science. Because there are several kinds of skin afflictions that can happen in humans, the best way to determine a change in skin spot color is through a dermatologist's examination, especially if color change occurs rapidly on an already present mole or mark.