[Phyllodes tumor: histology and behavior]

The present study compares the biological behavior of a phyllode tumors to its histological characteristics. Traditional concepts are still valid since 100% of the tumors with severe atipicity recurred, while 76.9% of those with minimal atipicity did not. In certain cases, histological details provided the explanation for the evolution of the tumor. On those recurs cases with minimal atipicity 66.6% were treated with conservative surgery, probably with insufficient removal of healthy tissue to ensure that no tumor was left. No histological explanation was found for the rest of recurrences. However, they could be caused by the tendency of the tumor to grow with the same histological elements in multiple areas of the same or the opposite mammary gland. As previously demonstrated by other authors, the prognostic importance of the search for other histological features, such as number of mitosis, microscopical margins of the tumor, stromal overgrowing, necrosis, appearance of the epithelial component and the area with the most cellularity. It is suggested that all these features should be determined in each case of the phyllodes tumor.