Many women found an egg-sized lump under the armpit after pregnancy, when they thought it was an enlarged lymph node, they were so scared that they rushed to the hospital. The doctor said it was not a lymph node, but a “side breast”, no need for injections and medication, just observe. After weaning, the body gradually recovered, the armpit swelling has shrunk, but it is slow to return, I feel very distressed, even dare not wear sleeveless dresses, what is going on? Why do I have parametrium? During the embryonic period, human beings, like other mammals, have a breast line from the armpit through the nipple to the groin, and there are 6-8 pairs of original breasts on this line. In some cases, if they do not degenerate well, they will be left with “small breasts”, which is a congenital abnormality, medically called “polymastia”, with an incidence of 1% to 6%. Is the armpit lump a lesion that only grows after pregnancy? In fact, it is possible that the size of the parametrium in the armpit before pregnancy is relatively small, so most people do not pay much attention to the local bulge at that time. After pregnancy, due to the influence of hormones in the body, the parametrium gradually fills up and increases in size, just like the normal breast, and only then is it noticed. After weaning, the lump in the armpit usually softens and shrinks, but does not shrink or disappear. Do I need to cut off my side breasts? Most of the time, parastomal breasts are seen because of their aesthetic impact, but they are like “small breasts” that contain breast tissue and are therefore at risk for breast enlargement, fibroadenoma, and even breast cancer, and need to be checked regularly, just like breasts. If the lump is small and there are no obvious symptoms, it may not need to be treated. Surgery may be considered unless there is a gradual increase in the size of the gland with pain and discomfort; an abnormal mass is palpated in the parametrial gland with suspected associated tumor; there is a family history of breast cancer; or there is a significant bulge in the breast or an enlarged nipple or areola pigmentation that affects the appearance of the breast.