Utility of 24 hour bone scan in evaluation of bone involvement by soft tissue sarcoma

Accumulation of Tc-99m MDP in soft tissue malignancies occurs frequently. When tumor overlaps adjacent bone structures, the bone margins can be indiscernible on a regular bone scan. Additional views should be taken to differentiate bone from tumor, however, separation is sometimes difficult and not always successful. This report presents a patient in whom accumulation of Tc-99m MDP in a liposarcoma of the thigh disappeared on a 24 hour scan and bone margins were seen clearly. A possible mechanism for this phenomenon and its utility are discussed.