Fibroadenoma, phyllodes tumor

Fibroadenomas and phyllodes tumors comprise the vast majority of fibroepithelial tumors of the breast, though mammary hamartomas and periductal stromal tumor are also considered in this category. 

Fibroadenoma versus Phyllodes Tumor IHC and Molecular Approach... 

The main diagnostic dilemma involving fibroepithelial lesions of the breast is probably differentiating cellular fibroadenomas from benign phyllodes tumors, since... 

FIGURE 19.37 Proliferative activity in fibroadenomas versus benign phyllodes tumors. The fibroadenoma depicted in (A) and (B) shows no Ki-67 positive stromal cells, whereas that depicted in (C) and (D) shows focal ( 1 %) Ki-67 stromal cell immunoreactivity. Note the numerous positive ductal epithelial cells. Similarly, a benign phyllodes tumor may show minimal or no proliferative activity with Ki-67 as shown in (E-H). 

Ki-67 proliferation index does not reliably distinguish between fibroadenoma and phyllodes tumor. 

Molecular analyses in distinguishing fibroadenomas from phyllodes tumors have also been inconclusive. 

Noguchi S, Motomura K, Inaji H, et al. Clonal analysis of fibroadenoma and phyllodes tumor of the breast. Cancer Res. 1993 53 4071-4074. 

Sapino A, Bosco M, Cassoni P, et al. Estrogen receptor-beta is expressed in stromal cells of fibroadenoma and phyllodes tumors of the breast. Mod Pathol. 2006 19 599-606. 

Umekita Y, Yoshida H. Immunohistochemical study of MIBl expression in phyllodes tumor and fibroadenoma. Pathol Int. 1999 49 807-810. 

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