The diagnosis of breast cancer should be considered to be ruled out in patients who visit the breast clinic, regardless of the presence or absence of clinical symptoms and abnormal signs. The outpatient physician needs to take a careful history, perform a breast examination, clarify the patient’s knowledge of his or her own breast, perform a breast cancer risk assessment, and conduct further tests according to the patient’s specific situation. With the gradual expansion of breast screening and mammography, more and more breast cancer patients are being diagnosed in the preclinical stage, which means that more and more histological biopsies will be needed to diagnose breast cancer. The clinical need for a comprehensive and detailed analysis of the growth and dissemination of breast cancer from its symptoms, signs and imaging manifestations, based on the biology of breast cancer and the characteristics of breast anatomy. 1. Symptoms The three most common symptoms of breast disease patients are breast lumps, abnormal lesions shown by ultrasound or mammography and breast pain. Breast pain is one of the main causes of breast disease in patients. For premenopausal patients, ask about changes in breast pain before and after menstruation. Most breast pain is associated with hormonal irritation and swelling of the breast. The pain can radiate to the shoulders, upper extremities, and a burning sensation if muscle tension is present. More than 50% of women of childbearing age present with cyclic breast pain. For patients with breast pain, explanation and recommendation of physical therapy can be effective. Symptoms can be treated symptomatically in severe cases. Some breast pain manifests as pressure pain, which may be present in both benign fibrocystic lesions and malignant tumors, which are often combined with a more definite breast mass. The first symptom of most primary breast cancers presents as a palpable breast lump, often first detected by the patient themselves. Most breast cancers present as a single, solid mass without pressure. Fibrous cystic masses, sometimes characterized by large and small, sometimes well-defined and sometimes indistinct masses. For breast masses in young women who cannot be characterized, observation of 1-2 menstrual cycles can also help in differential diagnosis. Breast cancer can also present with symptoms such as skin thickening, depigmentation changes, axillary masses, and nipple discharge. Nipple discharge can be plasma, watery, milk-like, yellow, green, or bloody. Bloody discharge is often indicative of intraductal papilloma and occasionally bloody discharge in combination with papillary adenocarcinoma. Nipple discharge is often suggestive of benign in the following cases: 1, clear, or plasma discharge involving 2 or more large milk ducts; 2, non-self-induced discharge that requires squeezing the nipple to trigger the discharge and non-bloody discharge. Normally, the milk ducts also secrete a small amount of fluid. If the milk ducts above the collecting ducts are duplexed due to fibrosis or fluid thickening masses, clinical signs such as milk duct dilatation and cyst formation are seen. Diffuse skin erythema is more common in lactating mammary glands, and systemic antimicrobial therapy + local physical therapy is best for lactating patients with these symptoms. Non-lactating mammary glands with diffuse skin erythema, abnormally elevated white blood cell counts, and fever are more likely to have a breast abscess and can be treated with systemic antimicrobials, incision and drainage, or a combination of both. If there are no signs of infection in patients with diffuse skin erythema, a mammogram or biopsy is needed to rule out inflammatory breast cancer. Due to the widespread availability of breast screening, an increasing number of patients with no clinical symptoms and abnormal imaging are being seen on an outpatient basis. It is recommended to classify the imaging examinations and perform further examinations or follow-ups according to different classification categories. 2. Signs Clinicians should inform patients how to perform breast self-examination and what problems should be seen in the hospital if they appear on breast self-examination. However, a large randomized clinical trial of 266,064 women showed that between the 10th and 11th year of follow-up, 135 breast cancer deaths occurred in the self-examination group and 131 deaths in the control group, and that breast self-examination did not reduce breast cancer mortality; it substantially increased the detection of benign breast lesions. Breast self-examination is not a substitute for routine breast cancer screening, and this needs to be made clear to patients during outpatient visits. The purpose of breast examination is to detect and evaluate breast abnormalities. Breast examination is performed by visualization and palpation. Positive signs include palpable breast masses (or lumps), glandular thickening (or nodular sensation), nipple discharge (without breast masses), and skin abnormalities. Visual examination is performed to observe the appearance of the breast, the presence of skin and nipple abnormalities, and also to perform bilateral comparisons. Both localized elevation and localized depression (dimple sign) are suggestive of abnormalities, especially the latter, which often indicates superficial malignancy. Skin abnormalities include an orange peel appearance, erythema, and rupture. Diffuse breast erythema is usually considered inflammatory breast disease, but inflammatory breast cancer also often presents with skin erythema. Breast edema, orange peel-like appearance, and rupture are specific manifestations of locally advanced progressive breast. Careful observation of the nipple is needed. Nipple retraction, desquamation, and eczema-like changes should be excluded from nipple Paget disease. During breast palpation, a thorough examination of the bilateral submammary rhomboids is performed in sequence. The patient is usually placed in the as or standing position, but may also be placed in the lying position. Do not grasp and pinch the breast, and when examining a pendulous breast, the breast may be held up for examination. The most common abnormal sign associated with breast cancer on breast palpation is a breast mass. The location of the breast mass is recorded, usually according to the superior internal, superior external, inferior external, inferior internal, and central (areolar) areas. If the mass is located in the marginal area of the breast such as the axilla, lateral border of the pectoralis major muscle, subclavian, or parasternal, it needs to be described. Describe the number, shape, border, size, mobility, and texture of the masses. Breast gland thickening (nodular sensation) is different from breast masses, which can be large or small and have unclear borders. Good mobility of the mass often suggests a benign tumor, but there are exceptions. The relationship between the mass and the skin, pectoralis major fascia, and Cooper’s ligament needs to be carefully observed. Because of the presence of infiltration, breast cancers do not have an intact envelope and often move with the surrounding breast tissue when the mass is pushed. Larger breast cancers are often more fixed and are not difficult to identify clinically. The presence of nipple overflow is examined during nipple palpation, and the number of overflow ducts (single duct, multiple ducts, unilateral nipple, bilateral nipple) and the nature of the overflow (colorless and clear, plasma, milk-like, brown, bloody) are recorded, and cytology is required for the overflow. Lymph nodes in the axillary, subclavian and other breast drainage areas need to be carefully examined. Enlarged lymph nodes may indicate metastasis, which can be a guide to the treatment plan and surgical options for breast cancer.