Cytological Findings in Benign Phyllodes Tumors.

OBJECTIVE: Phyllodes tumors are fibroepithelial breast lesions with many cytological and histopathological similarities to fibroadenomas. The aim of this study was to investigate cytological findings in benign phyllodes tumors.

STUDY DESIGN: Seventy-six histologically proven cases of benign phyllodes tumors were selected from 1982 to 2017. Cytological criteria, including cellularity, the number and shape of epithelial clusters, the shape and number of stromal fragments, and the presence of atypia, were evaluated.

RESULTS: Cytological slides were hypercellular and showed dimorphic populations of cells. The epithelial clusters were moderate in amount and had a bonsai-like configuration. The stromal fragments consisted of oval-to-spindle shaped cells with preservation of the cytoplasm. Some popcorn-like cells and intranuclear inclusions in stromal cells and deposition of pinkish and amorphous material at the border of the stromal fragments were also noted in the stromal cells.

CONCLUSION: Stromal hypercellularity and large amounts of stromal fragments, the presence of bonsai-like epithelial clusters, and deposition of amorphous pinkish material at the border of the stromal fragments, as well as newly observed findings including the presence of intranuclear inclusions and popcorn-like nuclei in the stromal cells, can aid in the diagnosis of phyllodes tumors.