[Natural history and diagnosis of some mammary lesions].

A topographical study of the galactophoretic system enables better localization and interpretation of a number of mammary lesions. Histology throws light on histogenesis of the various lesions. Attention has been drawn by the author on the part played and the modifications undergone by myoepithelial cells during the various phases of activity of the gland and the development of tumoral formations. Cytological and histological diagnosis is based in the first place in clinical signs. Nipple discharge testifies of lesions that have developed within the large galactophoretic ducts. They can be diagnosed by cytological examination; although some cases can remain controversial. Fluid parenchymatous masses indicate mono- or multilocular large cysts. Carcinomas but seldom progress under such a form. They are necrotizing and haemorrhagic circumscribed cancer. Dense masses represent lobular lesions. While diagnosis of an adenofibroma causes no problem, adenosis and sclerous adenosis can give rise to a diagnosis of malignancy. In the author's opinion, hyperplasia of myoepithelial cells should be distinguished from in situ lobular carcinoma, the latter having a decidedly different prognosis. In the majority of cases, morphology of the carcinoma is not contributory: some varieties, such as mucous colloid with epidermoid metaplasia, cylindroma, "medullar" and tubular carcinoma, are histologically well-individualized but their progress is usually similar to that of the other varieties of cancer. In spite of certain shortcomings, cytological examination remains one of the best methods of investigation and diagnosis in mammary gland lesions.