Enlarging biopsy-proven fibroadenoma: Is surgical excision necessary?

Core biopsy-proven fibroadenomas that enlarge on clinical or imaging follow-up are often surgically excised to exclude an associated malignancy. The purpose of this study was to assess how often malignancy is detected upon excision, and to determine whether excision of enlarging, biopsy-proven, uncomplicated fibroadenomas is still warranted.

Review of our institutional pathology database from 2000 to 2010 identified 1117 cases of fibroadenoma, and retrospective chart review, including review of pathology and imaging findings of all these records, was performed.

1117 cases of fibroadenoma were identified in a population of women ranging from ages 17 to 78. Of these, 378 (33.8%) were diagnosed by ultrasound core needle biopsy and formed the study population. Of the 378 cases, 24 (6.3%) had co-existent atypia and were immediately excised; these cases were excluded. An additional 107 (28%) were lost to follow-up. Of the remaining 247 cases, 201 (81%) showed stability on follow-up imaging (mean 31.5 months), and 46 (18.6%) enlarged on follow-up. Of the 46 biopsy proven fibroadenomas that enlarged, 19 had a biopsy at initial presentation and 27 underwent biopsy after they enlarged. Seventeen of the 19 were excised after enlargement, and pathology confirmed fibroadenoma in all cases (100%); two enlarged on initial follow-up imaging but remained stable for at least three years on continued follow-up. Of the 27 cases which were biopsied after enlargement, 23 revealed fibroadenoma on core biopsy, 3 had fibroadenoma with associated atypia with subsequent surgery revealing fibroadenoma and no associated malignancy, and one showed fibroadenoma with smooth muscle with subsequent surgery showing phyllodes tumor.

Based on this study, enlarging biopsy proven fibroadenomas are not associated with malignancy; therefore, surgical excision does not seem warranted. For presumed enlarging fibroadenomas on imaging, core biopsy should be performed to exclude associated atypia or phyllodes tumor. Finally, surgical excision is indicated for lesions with associated atypia or suspected phyllodes and for symptomatic lesions or cosmetic reasons.