Breast pain, simple mammary epithelial hyperplasia, is an early lesion of structural malformation of the breast. first described by Bloodgood in 1922 and noted by Semb in 1928 as a painful breast with a lump, called simple adenofibromatosis. in 1931 Beatle called it simple desmoplastic epithelial hyperplasia of the breast; in 1948 Gescnickter It was called breast pain. It has been used until now. The occurrence and development of the disease are closely related to the endocrine status of the ovaries. A large number of data show that when the ovarian endocrine disorders, excessive secretion of estrogen and relative reduction of progesterone, not only stimulate the proliferation of breast parenchyma, but also cause irregular proliferation of terminal duct epithelium, resulting in ductal dilatation and cyst formation, as well as excessive proliferation of interstitial connective tissue with collagenization and lymphocytic infiltration due to the loss of the inhibitory effect of progesterone on estrogen. II. Pathogenesis The pathological features of pure mammary epithelial hyperplasia are: 1. Gross morphology: the lesion area of mammary hyperplasia is tough in texture, without envelope, with unclear boundaries with normal tissue and small grayish-white granular appearance in cut surface. 2. Histological morphology: microscopically, the terminal milk ducts and alveolar epithelium are seen to be proliferated and shed, making the milk ducts swollen and distended; causing the ducts of the breast to dilate and form small cysts; the lobules of the breast are proliferated with fibrous tissue, and the lobules are fused with each other; the interlobular stroma is infiltrated with lymphocytes. The main manifestations are breast swelling and pain, breast lumps, and have obvious cyclical and self-limiting characteristics. 1.Breast distension and pain That is, intermittent breast distension and pain starts 3-4 days before menstruation and decreases sharply after menstruation, which is cyclical. The pain can be diffuse dull pain or restricted stabbing pain. It usually affects only one breast, but can also involve both sides, with one side being more severe. The pain is mostly confined to one part of the breast, about 50% in the upper outer part and 20% in the upper middle part, with pressure in the painful area. The pain is sometimes very intense and radiates to the scapula and axilla, and worsens with mood swings, or with exertion, rainy weather, etc. Most of the patients have short and scanty menstrual periods, and the symptoms may be reduced when they are emotionally stable or in a relaxed mood, and may wax and wane with happiness and anger. The pain is sensitive to external stimuli such as rubbing of clothes, walking slightly fast or moving the upper limbs slightly hard, which can aggravate the breast pain. 2. Intramammary lumps often occur symmetrically in the breast bilaterally, and can be scattered throughout the breast or confined to a part of the breast, especially in the upper outer quadrant of both breasts. They are nodular to palpation, varying in size, not hard in texture and poorly defined in the surrounding tissue, and can be pushed. The size of the lump varies with menstruation, becoming larger and harder before menstruation and smaller and softer after menstruation. Some patients are accompanied by nipple overflow. 3.Self-limiting and repetitive disease The disease can not be cured by itself. The symptoms disappear on their own, especially after marriage, pregnancy and breastfeeding, but sometimes recur; it can heal on its own after menopause. The following clinical features should be considered for the diagnosis of this disease: 1. Periodic pain and lumps in one or both breasts associated with menstruation in women of childbearing age. 2. Small granular masses that are not hard in texture can be palpated on examination. 3. The disease is self-limiting and recurrent in the course of development.