What are paramammary glands? During embryonic life, 6-8 pairs of mammary gland primordia are formed by the ectoderm on the breast crest between the axilla and the medial groin. Normally, only one pair of primordia in the chest will eventually develop into a breast, while the rest of the primordia will degenerate and disappear during the embryonic period. If these primordia do not degenerate completely, multiple nipples and breasts remain, which are clinically referred to as paramamammary glands. This means that humans, like mammals, have 6-8 pairs of breasts during the embryonic period, which gradually degenerate into a pair of breasts during the course of embryonic development. Many of these are incomplete paramammary glands (not having both nipple and glandular tissue), which can appear swollen like normal mammary glands before menstruation and during pregnancy and lactation. Some complete paramammary glands can also produce milk during lactation. The parammary glands themselves are not clinically significant, but some can affect the appearance, and some are larger and may cause local skin redness, itching, or even erosion due to sweat impregnation, and the parammary glands can also suffer from benign or malignant diseases like the normal breast. Should parammary glands be removed as soon as they are found? Many people advocate removing the parammary glands when they are found, because “parammary glands can develop breast cancer”. In fact, parammary glands are very common, but parammary cancer is very rare, and few doctors have the experience of treating more than two cases of parammary cancer in clinic. It should be said that parammary cancer is even less common than bilateral breast cancer. In fact, if there are no other risk factors, it is not reasonable to remove the parametrial glands simply to prevent breast cancer, because if all the parametrial glands are removed, then women who have breast cancer should remove the opposite breast that does not have cancer as well. What kind of parametrial glands should be removed? Generally speaking, there are some or more of the following points: 1) there is a mass or abnormal calcification in the parammary gland; 2) the parammary gland is large and often painful, which affects daily life; 3) the family has an aesthetic request to remove the parammary gland. The paramammary gland is a manifestation of incomplete degeneration of the original breast crest, not a newly grown lump, but it may appear only before menstruation and during pregnancy and lactation.