Dark spots on the inside of the cheeks may be pigmented moles or bleeding caused by trauma, leukemia, or melanoma. 1. Pigmented nevus: Some normal people with darker skin color have more active melanin cells in their body, which may cause melanin deposition in the gums, or even in the mouth, resulting in the formation of a plaque or nevus. 2. Trauma: Bite wounds, burns, or external impacts may lead to swelling of the soft tissues lining the oral mucosa, or traumatic blood blisters that look like a black spot. 3. Leukemia: generally the immunity of leukemia patients is relatively low, and the blood clotting function is relatively poor, so the skin surface, or the oral mucosa is very easy to appear bleeding phenomenon. 4. Oral melanoma: when oral melanoma occurs, oral mucosa black spots will also appear, and grow faster, this time need to be diagnosed in time after the corresponding treatment, to prevent serious consequences. If the black spots on the inner wall of the cheeks, there is pain or other uncomfortable symptoms, you should consult the doctor in time, so as not to delay the condition, resulting in adverse consequences.