Subcutaneous injection of the HIV-1 fusion inhibitor Enfuvirtide (FUZEON) may result in soft-tissue accumulation of Tc-99m MDP

Bone scintigraphy using Tc-99m methylene diphosphonate (MDP) was performed on a 16-year-old girl as a component of surveillance for recurrence of leimyosarcoma, resected from her right foot 7 years earlier. A symmetric pattern of increased radiotracer uptake was noted in the soft tissues of her upper arms, thighs, and abdomen, corresponding to sites of twice daily rotating subcutaneous injections of Enfuvirtide (FUZEON), a peptide that interferes with fusion of the HIV to host CD4 cells. Use of this medication should be included in the differential diagnosis of causes of soft-tissue uptake of Tc-99m MDP in patients with history of HIV infection.