Malignant Phyllodes Tumor in Young Adult: Histomorphological Review of a Very Rare Case

Malignant Phyllodes Tumor

Abstract

Introduction: Phyllodes tumor (PT) is infrequent among breast neoplasms, represent for less than 1% of all breast neoplasms, with 10% to 30% of them being malignant. The occurrence rate of malignant phyllodes tumor (MPT) is about 2.1 cases per million people.

Case Presentation: We report the case of a 36-year-old woman who had a significant mass in her right breast. Macroscopically, the cut surface was grayish-white with cystic areas containing a hemorrhagic mass, the tumor occupied nearly the entire breast with indistinct borders.The tumor measured 26x16x11 cm. Microscopically, the tumor exhibited a solid structure with ductal proliferation and hypercellular stroma forming a leaf-like appearance. Proliferation of fibrous connective tissue with dysplastic cell morphology and atypical mitoses was found in >10/10 high-power fields (HPFs). Malignant heterologous components included bone matrix with osteoclast-like giant cells and chondroid components. Immunohistochemical Ki67 staining was positive for >20% in cell nuclei.

Dissscusions and Conclusions: The tumor was relatively large with unclear infiltration boundaries, and contained malignant heterologous components, immunohistochemical Ki67 staining was positive for >20% in cell nuclei, confirming it as a case of malignant phyllodes tumor MPT. This case is notable due to its rarity and the patient's younger age compared to typical cases reported in the literature.