Metastatic Carcinoma Arising from Fibroadenoma of the Breast

Fibroadenoma of the breast is a common, benign condition. It is common among women of child-bearing age. A conservative approach for these benign tumors is the standard of care since the prevalence of breast cancer arising from a fibroadenoma is very low (0.02%). Fibroadenomas can be followed over time, rather than excised. Carcinoma-in-situ and invasive carcinoma have both been reported to arise from a fibroadenoma and various studies have reported the risk of malignancy increases 1.5to 3-fold following the diagnosis of fibroadenoma. We present two patients with a long history of a fibroadenoma who were found to have breast cancer metastatic to lymph nodes. In both cases, the primary tumor arose from the fibroadenoma.