ULTRASTRUCTURAL CHARACTERIZATION AND BIOCHEMICAL PROFILE OF HUMAN GROSS CYSTIC BREAST DISEASE

Human gross cystic breast disease is a benign condition affecting abou t 7-10 % of adult women occurring with the highest incidence in the pr emenopausal decade. Although breast cysts do not represent a preneopla stic condition per se, several studies indicate an increased breast ca ncer risk in women affected by this pathology. In this report we study 115 breast cystic fluid samples obtained by needle-aspiration from wo men with gross cystic breast disease. The samples were analysed bioche mically and the cells contained therein were observed at the electron microscope. According to their biochemical profiles, the cysts were su bdivided into three types: Type I, showing a Na/K ratio < 0.5 and a ty pical protein content; Type II, showing a Na/K ratio >10 and a protein content quite similar to plasma; Type III, showing a Na/K ratio betwe en 1 and 7 and an intermediate protein content. The electron microscop ic examination demonstrated that Type I cystic fluid cells exhibit mor phological features typical of actively synthesising and secreting cel ls, while the characteristics of Type II cells indicate a low metaboli c activity. Type III cells have characteristics typical of both Type I and Type II cells, thereby confirming the intermediate nature of this cyst type. We hypothesise that these cyst types could represent diffe rent developmental stages of a structural evolution pathway, during wh ich the biosynthetically active 'apocrine stage' would be the key step to cell neoplastic transformation.