[Susceptibility of intraductal papillomas to carcinogenesis based on 3-dimensional reconstruction study].

Surgical specimens from 16 patients with intraductal papilloma were subjected to 3-dimensional reconstruction studies of mammary ducts in order to detect early cancerous foci developing in papilloma, to analyze growth behavior of papilloma and to establish morphological features of papilloma particularly prone to cancerous change. Papilloma of the multiple type (10 cases) originated in the terminal duct lobular units (TDLU), while papilloma of the solitary type (6 cases) originated in the large ducts except for one. In 4 out of the 16 patients small foci of intraductal carcinoma were found during specimen reconstruction. Two of the four patients harbored minimal cancer as small as 3 mm or less. The carcinomas with multifocal origins in the TDLUs were anatomically connected with peripheral papilloma so far as to take the form of "cancer in papilloma". Papilloma preceding carcinoma was of the multiple type in 3 cases and of the solitary type in one. But according to the sites from which papillomas originated, 4 out of the 11 cases originating in the TDLU had cancerous foci, whereas none of the 5 cases originating in the large ducts did. This suggests that the peripheral papilloma is highly susceptible to cancerous change. From a clinical point of view, we proposed a nomenclature of peripheral vs. central papillomas instead of the conventional multiple vs. solitary.