Peritoneal Metastasis of Osteosarcoma in 99m Tc-MDP SPECT/CT Imaging.

An 11-year-old boy with history of conventional high-grade osteosarcoma in the left distal femur was referred to our department for 99m Tc-MDP whole-body bone scan. In addition to multiple bone lesions and pleura, abnormal high radioactivity was found in the abdomen. SPECT/CT revealed diffuse peritoneal thickening with calcification and increased radioactive uptake, which suggest peritoneal metastases. The most common metastases of osteosarcoma can be found in bone and lungs, whereas peritoneal metastases are extremely rare.