我们在此介绍一例良性肌腱鞘巨细胞肿瘤的病例，该肿瘤在放射性碘耐药性甲状腺癌患者的PET/CT检查中偶然发现，该患者主要存在非碘浓集病变。在接下来的3年内，该病变通过临床和当地MRI进行了跟踪观察。我们在此证明混合PET-CT成像的实用性，肿瘤的非碘浓集特性以及临床知识、其他成像和病理学方法的发现，可用于回答和诊断伴有已知甲状腺恶性肿瘤的偶发性良性肌骨肿瘤。作者：这是Thieme出版的开放获取文章，根据创作共用许可证发布，允许无限制使用，分发和复制，只要原始作品得到适当引用。(https://creativecommons.org/licenses/by/4.0/)。

We herein illustrate a case of benign tenosynovial giant cell tumor, which was incidentally detected as FDG-avid lesion on PET/CT in a patient with radioiodine refractory thyroid cancer, with predominantly non-iodine concentrating disease. The lesion was followed up clinically and with local MRI annually for subsequent 3 years. The utility of hybrid PET-CT imaging, the non-iodine concentration of the tumor along with clinical knowledge, and findings on other imaging and pathological modalities in answering and diagnosing incidental benign musculoskeletal tumors in a patient with known thyroid malignancy are presented here.The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution License, permitting unrestricted use, distribution, and reproduction so long as the original work is properly cited. ( https://creativecommons.org/licenses/by/4.0/ ).