Characteristics of breast cancer: Breast lump is the first symptom of breast cancer, mostly single. The lumps are hard with irregular edges, a few of them are as hard as rubber, which can be pushed in the early stage, but restricted or even fixed in the later stage; there is basically no pain in the early stage, but less than 1/3 of patients have dull pain and stabbing pain in the middle stage; if there is nipple erosion and scab, eczema-like cancer should be considered; if the whole breast is red and swollen, the lump looks like inflammation and develops rapidly, attention should be paid to whether it is inflammatory breast cancer. On physical examination, some patients may have fixed nipple retraction or deviation toward the lesion; local skin depression, called “dimple” sign, or “orange peel-like” change in advanced stage; and enlarged axillary lymph nodes. Other breast mass characteristics: 1. Breast fibroadenoma Most often seen in young women (around 20-30 years old), the mass is located in the upper outer quadrant of the breast, round or oblate, usually within 3 cm. Single or multiple, tough, smooth surface or nodular, clearly demarcated, no adhesions, and sliding sensation when touched. The lump is painless and grows slowly, but increases faster during pregnancy. 2.Mastopathy is caused by functional disorder of endocrine, and its essence is neither inflammation nor tumor, but disorder of normal structure. It usually has typical signs and symptoms and is easy to distinguish. Sclerosing adenopathy, on the other hand, often has hard nodules with indistinct boundaries and small size in the breast, which is often difficult to distinguish from breast cancer clinically and should be identified through various physical examinations. 3.Breast tuberculosis is relatively rare, which is clinically manifested as inflammatory lesions and can form lumps, but sometimes large and sometimes small, patients do not necessarily have tuberculosis, and it is often accompanied by enlarged axillary lymph nodes. 4.Breast cyst can be divided into accumulation of breast and accumulation of blood. The accumulation of breast is mostly seen in lactating or pregnant women, and it is not difficult to diagnose according to medical history and physical signs. The accumulation of blood is mostly seen in trauma, due to the accumulation of blood blocking the milk ducts, which is not absorbed and forms inflammatory masses. 5. Plasmacytoid mastitis is often caused by various reasons for blockage of the milk ducts, resulting in overflow of lipidic material from the milk ducts into the periductal tissue and causing sterile inflammation. In the acute stage, sudden breast pain, redness and swelling, nipple invagination and axillary lymph nodes may be enlarged, which can be easily misdiagnosed as inflammatory breast cancer. When the acute inflammation of the lesion limits subsides, there is a lump in the breast and it may adhere to the skin, which is also easy to be misdiagnosed as breast cancer. Malignant lymphoma of breast is rare, accounting for 0.04-0.52% of malignant tumors of breast. The age of prevalence is 50-60 years old, and it is common in women, and it is often solitary. The clinical manifestation is often a rapidly enlarging mass, sometimes occupying the whole breast, with a large mass or nodular or lobulated mass, with clear borders, firm and elastic texture, and no adhesion to the skin and breast. When the lump is large, the skin is thin and the blood vessels are dilated, causing rupture. The axillary lymph nodes may also be involved at the same time. It is often difficult to diagnose clinically and is not easily distinguishable from other malignant tumors on X-ray, and requires pathology to clarify.