[Genesis and extension of intraductal papillomas of the breast--a three-dimensional morphological study]

Graphic reconstruction of semi-serially sectioned breast specimens allowed a three-dimensional observation of intraductal proliferative lesions and their growth characteristics. Ten surgical specimens with intraductal papillomas obtained by microdochectomy were subjected to this study, and the primary site and extending behavior of papillomas were analysed. The results indicated: (1) In seven out of the ten cases papillomas appeared to arise from terminal duct lobular unit (TDLU) as multiple foci three-dimensionally independent of each other. (2) Secondary ductal involvement by multiple papillomas attained to as far as subsegmental or segmental level. (3) On the other hand solitary papilloma arose from segmental duct without involving TDLU. (4) Both solitary and multiple papillomas transformed and distorted the duct system while sustaining its basically arborescent pattern. (5) Duct papillomatosis, situated within TDLU, was often proved to be connected with multiple papillomas in more proximal ducts, and therefore was regarded as a prepapillomatous lesion. (6) Retention cysts associated with multiple papillomas were accounted for by intraductal proliferations obstructing outflow tracts.