Cellular changes in the mammary gland epithelium during the menstrual cycle. A computer image analysis study.

While examining fine needle aspirates of lesions, it became evident that preovulatory aspirates differed from postovulatory ones. Proliferation activity was noted in cells and in fragments aspirated during the luteal phase. In order to verify this observation, pairs of smears obtained during different phases of the menstrual cycle from eight fertile women were studied by computer image analysis. Using discriminant analysis based on nuclear features extracted from the digitized cell images, 84.87% of all cells were correctly classified as preovulatory or postovulatory, according to the smear of origin. When the classification was restricted to only the cells from each woman, a 100% correct identification of cell types was obtained, which supports the visual observation that there are cellular changes in the mammary epithelium correlated to the menstrual cycle. Since some proliferative changes may mimic atypia or malignancy, these findings suggest that it is advisable to perform needle aspirations of breast lesions during the preovulatory phase of the cycle.