The occurrence of cysts in the female breast is common. Some of these cysts develop, apparently, from distended lactiferous ducts (galactocele). They are comparatively unimportant and are not puzzling from either a morphologic or a clinical point of view. The presence of multiple, often small, cysts in the gland tissue proper of the breast is of far greater importance. The interpretation of their nature and histogenesis has been studied by a great number of authors, yet no consensus has been arrived at. This is demonstrated sufficiently by the large number of names given to this condition. The confusing nomenclature includes, among others, the following terms: polycystic breast, cystic disease, polycystoma, hydrocystoma, cystic epithelioma and epitheliofibrosis of the breast.
The main questions that arise in studying this condition concern the histogenesis of the cysts, the nature of their matrix, the character of the epithelial proliferation and its relationship to neoplastic conditions