What is accessory breast? You need to know the pathogenesis

Accessory breasts are breasts that appear in addition to normal breasts. The sizes of accessory breasts are different, so they are easily overlooked. What is accessory breast is also a question that many people want to know. In fact, accessory breasts are mainly caused by congenital developmental abnormalities and can be removed through surgery later.

1. Causes of disease

Polymastia is a congenital developmental abnormality. When the fetus is 9 mm long, 6 to 8 pairs of nipple-like local thickenings occur on the ectoderm epithelial tissue on both sides of the ventral side, from the axilla to the inguinal line (milk line). These are the mammary rudiments. Under normal circumstances, except for one pair on the chest, the remaining rudiments degenerate and disappear before birth. If any of them do not degenerate, accessory mammary glands are formed, resulting in multiple nipples or multiple breasts. If there is glandular tissue below the nipples, it is called complete accessory mammary glands. Those with only nipples but no mammary gland substance are called accessory nipples. Some have no nipple protrusions, only bilaterally symmetrical localized depressions or small areas of skin pigmentation.

2. Pathogenesis

1. Location of disease: Accessory breast can be seen at any point on the mammary ridge, but is more common on the chest. It is rare to occur outside the mammary ridge, such as the face, upper arms, scapular area, back, thigh, etc. This is called malposed breast, lost breast or aberrant breast. Accessory breast is more common in the axilla. Zhang Fengzhen (1993) reported a case of primary squamous cell carcinoma of the axillary accessory breast, and Deng Huixu (1993) reported a male (1984) reported 100 cases of accessory breasts, of which 95% were in the bilateral axilla and only 5% were in other parts.

2. Pathological changes

(1) Gross findings: Multiple breasts are located in the axilla and are generally 1 to 6 cm in diameter. They are unencapsulated, soft in texture, and may be adhered to the skin. The cross-section shows grayish white or grayish yellow, flexible breast tissue in the adipose tissue, with scattered yellow adipose tissue.

(2) Microscopic observation: Mammary ducts and mammary lobules composed of alveoli can be seen. Obvious proliferation of interstitial fibrous tissue and some mammary duct proliferation and expansion can be seen between the lobes, forming a structure similar to cystic mastitis. Some cases may also present with changes similar to chronic cystic mastitis due to the infiltration of a large number of lymphocytes.