Chapter 146 Breast: Cyst
THE CHALLENGE
Scope of the Problem: Some authors estimate that cysts form in the breasts of roughly 50% of women during their reproductive years. Roughly one in four women requires medical attention for some form of breast problem; often this takes the form of a palpable mass. The most common cause of a palpable breast cyst is fibrocystic change, which is estimated to be found in one third to three fourths of all women. Dilation of ducts and complications of breastfeeding (galactoceles, abscess) may also cause cysts.
TACTICS
Relevant Pathophysiology: The pathogenesis is not clear for the most common types of cystic change (those associated with fibrocystic change). Cyclic changes in hormones induce stromal and epithelial changes that may lead to fibrosis and cyst formation. Cysts may be single or in clusters, with some as large as 4 cm in diameter. Small cysts have a firm character and are filled with clear fluid, giving the cyst a bluish cast. Larger cysts may have a brown color resulting from hemorrhage into the cyst. Inspissated secretions or milk may form a cystic dilation of ducts (galactocele, ductal ectasia) that may be palpable as a cystic mass. Variable degrees of fibrosis and inflammation may be seen in the surrounding stroma. (Leakage of cyst fluid into the surrounding tissue induces an inflammatory response that may alter physical findings and imitate cancer.) The microscopic findings associated with breast cysts depend on the pathophysiologic changes involved.