The glands of the human mammary gland originate from the ectoderm. At the 6th week of embryonic life, 6 to 8 pairs of mammary primordia are formed on the ventral surface of the embryo from the axilla to the groin, showing 2 bands of “milk lines”. At the 9th week of embryonic life, all the mammary primordia are degenerated except for the pair of mammary primordia located in the 5th intercostal space on the midclavicular line, which are preserved and develop normally. If one of the breast primordia on the “breast line” does not shrink in time and continues to develop, a parametrium is formed after birth. Paramomastia can occur in both men and women, with an incidence of about 1% to 5%, with a male to female incidence of 1:5.