Differentiation of phyllodes tumors versus fibroadenomas

To determine if mammographic and sonographic findings allow discrimination between phyllodes tumor and large sized fibroadenoma, which mimic each other in the clinical, radiologic and histopathologic appearances.

Thirty-one histopathologically proven masses including 12 phyllodes tumors and 19 fibroadenomas 3 cm or greater in diameter were compared. In total 28 women were retrospectively evaluated by mammography and pre-operative sonography.

Mammography revealed a high-density mass compared with surrounding fibroglandular breast tissue to be present in 9 of the 12 (75%) phyllodes tumors and 7 of the 19 (37%) fibroadenomas. At sonography a mass, which had a round or lobulated shape, marked posterior acoustic enhancement and intramural cystic areas, were statistically significantly more likely to be phyllodes tumors than fibroadenomas. None of the other mammographic or sonographic characteristics proved to be useful in differentiating phyllodes tumors and fibroadenomas.

Although masses of high density at mammography, circumscribed border associated with posterior acoustic enhancement and internal cystic areas at sonography should suggest the diagnosis of phyllodes tumors rather than large sized fibroadenomas, there was a substantial overlap in the mammographic and sonographic characteristics of these two tumors. Therefore, an excisional biopsy would be necessary for equivocal masses.