Malignant Phyllodes Breast Tumor: A Rare Case of Metastasis in Skeletal Muscle Detected on 18-Fluorodeoxyglucose Positron Emission Tomography.

Rapidly growing cystosarcoma phyllodes tumor (PT) of the breast are rarely encountered. Distant metastases are not uncommon in malignant PTs; however, rare sites of metastases are sometimes observed. Here, we present the case of a rapidly metastasizing malignant PT in which skeletal muscle metastasis was identified on 18F-fluorodeoxyglucose-based positron emission tomography-computed tomography reflecting its aggressive course and poor prognosis.