Atypical Distant Metastasis of Breast Malignant Phyllodes Tumors: A Case Report and Literature Review

Figure 2

Microscopic aspect of the primary tumor (a, b, c, d, e) and medullar metastasis (f). (a, b) Predominant benign PT component. The stroma is more cellular than a fibroadenoma. Stromal cellularity may be higher in the zone adjacent to epithelium without atypia and mitosis ((a) magnification ×2, (b) magnification ×200), (c, d) malignant PT component observed near the cutaneous ulceration (arrow). We observed a high stromal cellularity with atypia and mitosis without epithelial structure. There was no involvement of the tissue beneath the nipples nor lymphovascular or neural invasion. ((c) magnification ×2, (d) magnification ×200), (e, f) malignant primary (e), and medullar metastasis (f) PT at magnification ×400. We observed a similar histologic pattern: a cellular stromal proliferation with atypia and mitosis (arrows). No epithelial components. All immunostainings were negative (estrogen receptor, progesterone receptor, pankeratin AE1, AE3, and PS100, desmin, CD34, caldesmon, and CD99) except for a focal staining with Smooth Muscle Actin antibody.