Rebound Thymic Hyperplasia in Osteosarcoma After Chemotherapy: 'Inverted V' Phenomenon in theF-18 FDG PET Study

摘要

A 14-year-old girl with osteosarcoma of right humerus is under the status of post operation and post chemotherapy. Six months after chemotherapy, an F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) study of whole-body is performed for evaluation of her previous treatment response. In addition to the non-specific radioactivity of the nasopharyngeal area, an "inverted V" pattern with diffusely increased accumulation of FDG is demonstrated at the mediastinum. This phenomenon represents rebound thymic hyperplasia which was resulted from the effect of recent chemotherapy. Further surgical intervention or chemotherapy is unnecessary in this situation. No imaging evidence of recurrence in the following six months was noted. Clinical history should be reviewed to prevent misinterpretation of rebound thymic hyperplasia as relapsed malignancy.