Core needle biopsy as a diagnostic tool to differentiate phyllodes tumor from fibroadenoma.

HYPOTHESIS: Core needle biopsy is a useful diagnostic tool in differentiating phyllodes tumor from fibroadenoma.

DESIGN: The radiology database was queried for patients who underwent core needle biopsies of fibroepithelial lesions that raised the possibility of phyllodes tumor. These diagnoses were then compared with the final pathological diagnoses after surgical excision.

SETTING: The data were gathered from the Comprehensive Breast Center, Columbia Presbyterian Medical Center, a tertiary care, university-based medical center.

RESULTS: From August 21, 1998, to December 14, 2001, 57 core needle biopsies were identified in which the specimen raised the possibility of phyllodes tumor. The median age of the patients was 42 years (range, 16-77 years). The median diameter of all lesions was 1.1 cm (range, 0.6-3.6 cm). Of the 57 specimens, 25 had core biopsies in which the pathological findings favored a diagnosis of fibroadenoma over phyllodes tumor. Twenty-three had initial core biopsies favoring phyllodes tumor. Nine of the core biopsies were equivocal. Of the 25 patients with specimens favoring fibroadenoma, excisional biopsy confirmed the diagnosis of fibroadenoma in 23, and phyllodes tumor was found in 2. The negative predictive value was 93%. Of the 23 core biopsies favoring phyllodes tumor, 19 were confirmed on excisional biopsy, while 4 were fibroadenoma. The positive predictive value was 83%. In the equivocal core biopsies, 5 were fibroadenoma and 4 were phyllodes tumor on final pathological analysis. None of the lesions studied were determined to be malignant on final analysis.

CONCLUSIONS: Core needle biopsy can significantly reduce the need for operative management of fibroepithelial lesions. A core needle biopsy with results favoring fibroadenoma should allow the breast physician to treat the lesion as a fibroadenoma, with observation and close follow-up or with enucleation. Core needle histologic examination of phyllodes tumor allows the physician to preoperatively plan the definitive management at one surgical procedure, reducing the need for reoperations.