Breast nodule 0.3 cm by 0.2 cm refers to the size of the breast nodule under ultrasound. It is mostly associated with benign breast tumors and malignant breast tumors. Benign tumors mainly include breast hyperplasia, breast fibroma, breast malignant tumors that is breast cancer and so on. 1. Benign tumors: (1) Breast hyperplasia: usually related to endocrine disorders, when the endocrine changes, easy to lead to the breast with parenchymal hyperplasia, through the examination will find that there are nodules in the mammary glands, but the texture is relatively soft and the edges of the nodules are clearer. (2) Breast fibroma: it is also a kind of breast disease, mainly due to the abnormally high sensitivity to estrogen, there are no obvious symptoms in the early stage, however, some patients may touch a lump in the mammary gland when they are swimming or taking a bath, and nodules in the mammary gland will be found through examination. 2. Malignant tumor: it is breast cancer, which is related to endocrine disorders, heredity and other factors. The influence of cancer cells may lead to the enlargement of the lump, and nodules will be found in the breast through examination. In addition to the above factors, breast nodules may also be caused by other diseases, such as breast adenoma, lobular tumor of breast, breast tuberculosis, mastitis, etc. In order to clarify the cause of the disease, it is recommended to consult the doctor in time and make diagnosis and analysis through breast ultrasound and mammogram, so as to understand the cause of the disease and then carry out the treatment in time.