Fine‐needle sampling in malignant phyllodes tumors: Clinicopathologic study of 22 cases seen at the Institut Curie

Abstract

The preoperative cytological diagnosis of malignant phyllodes tumor (MPT) is challenging due to the heterogeneity of its clinical, radiological, and morphological presentation. To better define the cytopathological characteristics of MPT, we reviewed 22 examples seen at the Institut Curie. The original cytologic diagnosis was benign breast tumor in four cases (18.2%), suspicious in seven cases (31.8%) (low-grade phyllodes tumor in six cases needing histological evaluation, suspicious of sarcoma in one case), and malignant in 11 cases (50%). Smears were composed of different proportions of clusters of epithelial cells (68.2%), phyllodes fragments (31.8%), spindle cells within stromal tissue (31.8%), isolated spindle-shaped or round cells (45.5%), and bipolar naked nuclei (22.7%). Giant cells and mitotic figures were also occasionally seen. The cytological findings on smears were correlated with histopathological observations. One of the difficulties to reach an accurate cytological diagnosis for MPT is the frequent overwhelming of clearly malignant sarcomatous cell by the presence of largely predominant clusters of epithelial cell.

Cytologic diagnosis of metastatic malignant phyllodes tumor of the breast in pleural effusion

“…The current case documented a clinically rare presentation of recurrent malignant PT presenting as massive unilateral pleural effusion and was diagnosed in effusion cytology. The cytologic features of single or clustered tumor cells with marked nuclear atypia and bizarre multinucleate forms were concordant with the literature . The degree of nuclear atypia, nuclear features including a single distinct nucleolus, irregular nuclear membrane, oval‐to‐spindled cellular contour and multinucleation all corresponded to that seen in the previous salvage excision.…”

“…The cytologic features of single or clustered tumor cells with marked nuclear atypia and bizarre multinucleate forms were concordant with the literature. 10 The degree of nuclear atypia, nuclear features including a single distinct nucleolus, irregular nuclear membrane, oval-to-spindled cellular contour and multinucleation all corresponded to that seen in the previous salvage excision. Metastasis in malignant PTs have been reported to only comprise of stromal element, 11 and that the aggressiveness of malignant PTs is derived from the stromal component.…”

“…9 It was suggested that cytologic hypercellularity, marked nuclear atypia of individual or clustered stromal cells, mitosis, phyllodes fragments, and bizarre multinucleated giant cells were indicative of malignancy in PTs. 10 The current case documented a clinically rare presentation of recurrent malignant PT presenting as massive unilateral pleural effusion and was diagnosed in effusion cytology. The cytologic features of single or clustered tumor cells with marked nuclear atypia and bizarre multinucleate forms were concordant with the literature.…”

“…FNAC diagnosis of PT is even more problematic due to the lack of tissue architecture and difficulty in identifying mitoses, two of the grading criteria . It was suggested that cytologic hypercellularity, marked nuclear atypia of individual or clustered stromal cells, mitosis, phyllodes fragments, and bizarre multinucleated giant cells were indicative of malignancy in PTs …”

Diagnosing breast lesions by fine needle aspiration cytology or core biopsy: which is better?

“…In FNAC of phyllodes tumor, a multitude of criteria had been assessed, with the most useful ones being the presence of large stromal fragments, hypercellular stromal fragments, and moderate to large numbers of dissociated stromal cells [68], lower epithelial/stromal ratio, rounded epithelial fragments with mild atypia, and the presence of columnar cells with intact cytoplasm [62]. The diagnosis of malignancy within phyllodes tumors by FNAC was more difficult, although some reported the presence of hypercellular smears, mitotic figures, phyllodes fragments, and atypia of stromal cells in malignant cases [69], whereas other authors cautioned that mitotic activity, one of the cardinal malignant criteria in histology, was difficult to assess in FNAC [68]. The malignant cytologic criteria were limited by the usually small number of malignant phyllodes tumors in the various series, and any of these proposed criteria would require further verification.…”