How long it takes for granulomatous mastitis to septicize depends mainly on the degree of bacterial infection and is closely related to the patient’s physical status. In granulomatous mastitis, acute septic lesions may develop in as little as 3-5 days, but in some chronic cases of granulomatous mastitis, the formation of septic lesions may last up to a month or more. In granulomatous mastitis with septic lesions, treatment should be aggressive surgical incision and drainage, and treatment with appropriate and sensitive antibiotics through bacterial culture and drug sensitivity testing of the pus. For larger pus cavities or more serious conditions, complete open drainage should be performed along with pathological examination of the removed tissue to rule out the possibility of malignant changes. The next treatment plan will be decided through auxiliary examination.