Utility of Bone Scintigraphy and PET-CT in the Surgical Staging of Skeletal Chondrosarcoma.

Objective: Surgical staging is paramount to treatment of primary bone sarcomas. Often, bone scintigraphy and/or positron emission tomography-computed tomography (PET-CT) are used to exclude skeletal metastases; however, skeletal metastases in chondrosarcoma are rare. The purpose of this study was to assess the utility of these staging methods in patients with chondrosarcoma.

Methods: We reviewed 138 (87 males, 51 female) patients, mean age 54±20 years, with a chondrosarcoma, who had completed a bone scintigraphy or PET/CT as part of surgical staging. Sensitivity, specificity, and positive/negative predictive value of the scans was calculated.

Results: Seventeen (12%) patients had a positive bone scintigraphy or PET-CT for skeletal metastases. In cases of bone scintigraphy (n=11), 6 were benign and 5 were skeletal metastases. In cases of PET-CT, 6 were skeletal metastases, 3 were positive and 3 benign. All positive cases regarded dedifferentiated chondrosarcoma. The overall sensitivity and specificity of a bone scan or PET-CT was 100% and 93.1%; with a positive and negative predictive value of 47.1% and 100%, respectively.

Conclusions: Skeletal metastases at presentation of chondrosarcoma are rare and associated with dedifferentiated chondrosarcoma. Bone scintigraphy or PET-CT should only be performed in cases of high grade and dedifferentiated histology.