Skin discoloration is common with melanoma. Melanoma is a deadly skin cancer and it often presents with a dark spot. It can suddenly increase in size or color or may even bleed. People who expose themselves to the sun for prolonged periods are at a high risk for developing melanomas and other skin cancers.
Anytime you have a new skin lesion or a skin lesion that abruptly changes color or size, a visit to the doctor is recommended.