F-18 FDG positron emission tomography imaging of rare soft tissue sarcomas: Low-grade fibromyxoid sarcoma and malignant hemangiopericytoma

Many sarcomas are of intermediate nature, with aggressive local behavior and low-to-moderate tendency to metastasize. A low-grade fibromyxoid sarcoma had abnormal glucose uptake in the principal tumor and contralateral lung metastases with pleural involvement demonstrated with F-18 FDG positron emission tomography (PET). A high-grade malignant hemangiopericytoma had abnormal glucose uptake in the principal tumor and a metastasis in an ipsilateral paratracheal lymph node, but was falsely negative in a small adjacent intraparenchymal lung metastasis. F-18 FDG PET could be useful in rare soft tissue sarcomas to demonstrate sites of possible metastasis and direct biopsy, but is of uncertain negative predictive value with small tumor deposits.