Two plus signs of mammary decidualized cells suggest that the patient’s nipple discharge contains a high number of decidualized cells and that further diagnosis of the lesion is needed before treatment. The clinical symptoms of nipple discharge are likely to occur after the development of breast lesions. For example, patients with breast hyperplasia may present with plasma discharge, patients with intraductal papilloma may present with brown or bloody discharge, patients with mastitis may present with purulent discharge, and patients with breast cancer may present with bloody discharge. Examination of nipple discharge can help the doctor to make a diagnosis of the condition. During the routine examination of nipple discharge, two plus signs of decidual cells suggest that there are more decidual cells in the patient’s nipple discharge, which may be benign lesions such as ductal dilatation of mammary gland, intraductal papilloma, and malignant lesions such as breast cancer cannot be ruled out. It is recommended that the patient should undergo further examinations, such as pathologic examination and breast ductoscopy, in addition to enhanced CT and enhanced MRI. If benign lesions are diagnosed, symptomatic treatment is the mainstay, and antibiotics are needed to fight infection, and patients with serious conditions can have the lesions surgically removed. If the diagnosis is malignant lesions, radical surgery must be taken, and then assisted with follow-up treatment.