The nipple is an essential part of the breast. Under normal circumstances, it is cylindrical in shape, protruding approximately 1.5-2 centimeters from the breast surface and appearing as a small nodule. If the nipple does not protrude above the breast skin and cannot be pulled back to its normal position, it is considered inverted. Inverted nipples can affect sexual intimacy and breastfeeding after childbirth, and are prone to causing local inflammation and eczema.So, what causes nipple inversion?
Causes of congenital nipple inversion:
Cause 1: Hypoplasia of the smooth muscle in the nipple and areola
The nipple contains openings for milk ducts, surrounded by smooth muscle fibers. Inverted nipples are pulled inward by muscle fiber bundles encircling the ducts and inserting into the dermis beneath the areola.
Cause 2: Underdeveloped lactiferous ducts
Underdeveloped ducts fail to form proper conduits, instead forming cord-like tissue. The lack of supportive tissue beneath the nipple also contributes to inversion.
Causes of acquired nipple inversion:
Cause 1: Disease-related
Common in conditions like inflammation or tumors that invade breast ducts, ligaments, or fascia, causing contraction of the affected structures.
Cause 2:Improper breast binding or wearing excessively tight bras during adolescence
Tight constriction impairs blood circulation, leading to underdeveloped breasts and acquired nipple inversion.
Cause 3: Nipple inversion caused by breast surgery
During breast reduction procedures using the dermal pedicle technique, tension and scar contraction may also induce nipple inversion.
In secondary nipple inversion, infection is a primary contributing factor. This typically involves inflammation of the mammary ducts accompanied by fibrosis, where scar contracture impairs normal development and causes nipple inversion.