Malignant Fibrous Histiocytoma
Most common soft tissue sarcoma of older adults.
Contains both fibroblastlike and histiocytelike cells in varying proportions.
Distant metastasis most commonly occurs to the lung (90%), bone (8%), and liver (1%).
Peak incidence in the fifth and sixth decades, but an age range of 10-90 years.
Most commonly in the extremities (70-75%, with lower extremities accounting for 59% of cases), followed by the retroperitoneum. Arises in deep fascia or skeletal muscle.
Most common clinical presentation is an enlarging painless soft-tissue mass in the thigh, typically 5-10 cm in diameter. Two thirds of tumors are intramuscular.
Associations to associated with hematopoietic diseases such as non-Hodgkin lymphoma, Hodgkin lymphoma, multiple myeloma, and malignant histiocytosis.
Retroperitoneal MFH usually presents with constitutional symptoms, including fever, malaise, and weight loss. The tumor is often larger than 10 cm in diameter at presentation and may cause displacement of the bowel, kidney, ureter, and/or bladder. May occur after radiation or shrapnel injury.
Muscle density on CT. Can have hypodence regions.
Calcification 5-20% any pattern. Also heterotopic bone.
Heterogeneous on MRI, T1<T2
Enhances, hypervascular and high uptake of FDG and on MDP and gallium scans.