Phylloides tumor: findings on mammography, sonography, and aspiration cytology in 10 cases.

Phylloides tumor is a rare fibroepithelial breast tumor that occasionally has unpredictable clinical behavior. In nine cases of histologically benign tumors and one case of malignant phylloides tumor, the findings on physical examination, mammography, sonography, and aspiration biopsy were correlated retrospectively with the histologic diagnosis of resected specimens. Mammograms showed a round or lobulated benign-appearing opacity in nine cases; one small tumor was missed mammographically. Sonography depicted all tumors as mostly solid masses. Sonographic features included low-level internal echoes, either uniform or scattered; smooth contours; and no significant posterior shadowing. Intramural cysts were shown in six cases. Neither mammography nor sonography allowed reliable differentiation between benign and malignant phylloides tumors. Aspiration biopsy permitted accurate diagnosis of seven benign tumors. The malignant phylloides tumor was classified as a malignant tumor, but the definite differentiation from a carcinoma could not be made. Two histologically benign phylloides tumors were misdiagnosed as carcinomas. Although uncommon, phylloides tumor should be considered in the differential diagnosis of mammographically benign-appearing breast masses, especially if sonography shows intramural cysts within a well-defined solid lesion. Aspiration cytology is unreliable because of the inhomogeneity of the tumor; both intraoperative frozen section and permanent sections are needed for correct histologic diagnosis.