A huge malignant phyllodes tumor of the breast with osteoclast-like giant cells: a case report.

The malignant phyllodes tumor (PT) of the breasts is a rare type of fibroepithelial neoplasm. Osteoclast-like giant cells (OLGCs) exist in many types of tumors. But malignant PTs with OLGCs were rarely reported. Here, we presented a case of a 49-year-old woman who had a 23 cm ×21 cm ×6 cm mass which was growing for 2 years in her left breast. The patient had moderate anemia due to the hemorrhage and exudation on the surface of the tumor. The imaging examinations such as PET-CT found no lymphatic involvement and distant metastasis. We performed mastectomy with a 2 cm surgical margin and free skin flap transplantation to restore the big wound. The vacuum assisted closure (VAC) system was used to promote wound healing. Histological examination of the surgical specimen showed atypical spindle-like stroma cells, marked nuclear pleomorphism, focal necrosis, and mitotic activity. Typical leaf-like architectures of PTs were observed in some regions. OLGCs were found in many sections of the tumor with a number of vascular proliferations. The final diagnosis was malignant PT with OLGCs. After a three-month follow-up, no local recurrence or metastasis was found. Autogenous skin grafts with VAC are available for large area skin defect after excising a huge breast tumor. The presence of OLGCs in malignant tumors may be related to necrosis and hemorrhage of the tumor. These findings also provide opportunities for understanding the mechanisms of tumor formation and development.