[Morphology of dysplasia and small cancer of the breast].

The results of histological study of material from sectoral resection of 285 mammary glands (MG) from 265 patients with fibrocystic disease (FCD) are presented. 112 cases of a nonproliferative FCD and 173 cases with different variants and degree of proliferation and atypia of the duct and lobules epithelium are recorded. Slight proliferation is observed in 66 cases, mild in 43 cases, pronounced proliferation corresponding to the atypical hyperplasia according to the WHO classification of MG tumours (1981) is found in 30 cases; ductal and lobular carcinoma in situ is observed in 16 cases. A long-term follow-up showed the invasive MG carcinoma in the preserved part of MG to develop in 3 of 172 FCD cases (1.7%). A frequent combination of the atypical hyperplasia foci with an intraductal and lobular carcinoma in situ, revealed in 60 cases of the MG small carcinoma (from 3 to 10 mm in size) with a focal invasion, is in favour of the morphogenetic link between dysplasia and MG carcinoma. Electron-microscopic examination of a proliferative FCD (12 observations) and invasive carcinoma (15 observations) established an enhancement of the specific ultrastructural differentiation in parallel with an increase of the epithelial proliferation but did not reveal the ultrastructural signs of malignant transformation.