CASE OF THE MONTH
Phyllodes Tumor
September, 2020
The 52-year-old patient presented with an 18-month history of a rapidly growing, palpable, tender breast mass. There is moderate periductal stromal hypercellularity and moderate cellular pleomorphism with atypia. Lipoblasts are easily identified throughout. Mitotic figures are frequent. This case was diagnosed as a borderline phyllodes with a liposarcomatous component.
The WHO classification system recognizes the borderline phyllodes as a fibroepithelial lesion which meets criteria of modest stromal hypercellularity, moderate cellular pleomorphism, moderate atypia intermediate mitoses (5-9 mitoses per 10 HPF), intermediate margins, and rare heterologous differentiation.