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

Abstract

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. 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. 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. 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.