Whether a breast nodule of 7.6 mm x 6.4 mm is serious or not needs to be assessed in relation to the nature of the nodule, which may be benign or malignant. Benign nodules are usually not serious, including mastitis and breast hyperplasia; malignant nodules are mainly for breast cancer and are more serious. 1. Benign nodules: (1) Mastitis: it may be caused by inflammation of the breast tissue due to inflammatory reaction. This kind of disease is not serious and can be cured through timely treatment, and the prognosis is generally good. (2) Mammary hyperplasia: it is a relatively common benign breast disease in clinic, through timely treatment, the prognosis is good. (2) Malignant nodule: mainly refers to breast cancer, which is a malignant tumor of the breast. The disease is serious and complicated, and requires immediate surgical treatment. To determine whether a breast nodule is serious or not, it is not only based on the size of the breast nodule, but also on the nature of the breast nodule, its location and related symptoms. It is recommended that patients with breast nodules go to regular hospitals for timely consultation and standardized treatment after a clear diagnosis under the guidance of a doctor.