A Case of Phyllodes Tumor of the Breast with Mixed Liposarcoma: Case Report and Literature Review

• Published in: OncoTargets and therapy Vol. 14; pp. 3003 - 3011
• Main Authors: Tu He Ta Mi Shi, Mei Er, Wang, Ning, Yao, Qing, Dong, Shuang-Shuang, Feng, Xiao, Zhao, Jin, Zou, Hong, Pang, Li-Juan, Qi, Yan
• Format: Journal Article
• Language: English
• Published: New Zealand Dove Medical Press Limited 01.01.2021; Taylor & Francis Ltd; Dove; Dove Medical Press
• Subjects: Adipocytes; Bone cancer; Breast cancer; Case Report; Case reports; Cyclin-dependent kinase; Cyclin-dependent kinase 4; Cyclin-dependent kinases; Cytokeratin; E-cadherin; Epidermal growth factor; Epithelium; Estrogen receptors; Fibroadenoma; Fluorescence in situ hybridization; Liposarcoma; Literature reviews; malignant phyllodes tumor; Mammography; MDM2 protein; Megakaryocytes; Metastases; Mitosis; mixed liposarcoma; Molybdenum; Physical characteristics; Progesterone; Stroma; Tumor cells; Tumors; Vimentin; China; breast cancer; mixed liposarcoma; malignant phyllodes tumor
• ISSN: 1178-6930; 1178-6930
• DOI: 10.2147/OTT.S298379

Phyllodes tumors (PTs) account for less than 1% of breast tumors, and malignant PTs account for even less. Here, we described an unusual case of malignant PT with mixed liposarcoma (myxoid liposarcoma [MLP] and pleomorphic liposarcoma [PLP]). A 52-year-old woman discovered a small lump in her left breast. Twenty years later, the lump suddenly grew within 1 month. Mammography showed space-occupying lesions of the left breast. Histologically, the tumor was characterized by hypercellular stroma covering the epithelium and protrusion of the myoepithelium into the cyst to form a lobulated structure; regions of loose mucus and hypercellular structures alternated. A region of peripheral benign fibroadenoma was also observed, and many stellate and spindle cells or signet ring-like cells were identified in loose areas. Some areas showed a characteristic thin branching vascular pattern. In the cell-rich area, adipocytes and odd megakaryocytes were observed. Atypical mitotic figures were observed in the cell-rich and mucus areas (16 mitoses/10 high-power fields [HPF] and 2 mitoses/10 HPF, respectively). In the immunohistochemical analysis, a small number of tumor cells were positive for AE1/3 and vimentin, whereas all cells were negative for cytokeratin 34βE12, E-cadherin, p63, estrogen receptor, progesterone receptor, human epidermal growth factor receptor 2, and S-100, ruling out the possibility of metaplastic carcinoma. Interestingly, cyclin-dependent kinase 4, mouse double minute 2 (MDM2), and p16 were strongly positive in both loose mucus and cell-rich areas. However, the fluorescence in situ hybridization test results showed that MDM2 was not amplified. Combined with morphological characteristics, these findings supported that the tumor was a mixed malignant PT with MLP and PLP. Our patient did not receive radiation therapy, and after 47 months of follow-up, no recurrence or metastasis occurred. This case report serves to expand the morphologic spectrum of mixed malignant PT with liposarcoma.