Phyllodes tumor of the breast: an update.

Phyllodes tumor is an uncommon biphasic breast tumor, with the ability to recur and metastasize, and it behaves biologically like a stromal neoplasm. Traditionally, phyllodes tumors are graded by the use of a set of histologic data into benign, borderline, and malignant. In most series, all phyllodes tumors may recur, but only the borderline and malignant phyllodes tumors metastasize. On the basis of histologic features, prediction of behavior is difficult. The expression of many biological markers, including p53, hormone receptors, proliferation markers, angiogenesis group of markers, c-kit, CD10 and epidermal growth factor receptor have been explored, and many have been shown to be variably expressed, depending on the grade of the tumor. These markers are, however, of limited value in predicting the behavior of the tumor. Recently investigators have reported a plethora of genetic changes in phyllodes tumors, the most consistent of which seems to be 1q gain by comparative genomic hybridization. Some candidate genes have been mapped to various sites, and preliminary data suggest that some of these changes may be related to recurrence. It is foreseeable that more exciting data will be generated to help us to understand the etiology and pathogenesis of phyllodes tumor.