Erythema on the surface of breast is not necessarily cancer, it is related to mammary hematoma, capillary expansion, lack of micronutrients and other factors, as follows: 1, caused by skin inflammation, eat allergic food, drugs or contact with certain allergens lead to skin allergies, causing red patches on the chest skin and accompanied by local itchiness, but it has nothing to do with cancer; 2, caused by mammary hematoma, the breakage of subcutaneous capillaries will lead to breast hematoma, thus causing local erythema. This will cause local erythema, through the breast color ultrasound examination can be clear the scope of hematoma, and then treatment; 3, too much milk during breastfeeding will make the breast enlargement, resulting in thinning of the breast skin, subcutaneous expansion of capillaries will cause the surface of the breast skin red patches; 4, the body of the lack of micronutrients will lead to the emergence of red patches in the breast, the body of vitamins A, E, D, the human body is very important when the loss of trace elements lead to endocrine disorders, the loss of endocrine disorders, the loss of trace elements will lead to red patches. When the loss of trace elements leads to endocrine disorders, red patches of skin will be formed; 5. In the middle and late stages of breast cancer, the tumor volume grows too fast and too big, which will lead to varicose veins in the superficial skin, so when the breast is red, it looks like red patches.