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18F-FDG PET/CT Showing Rare Mediastinal Growing Teratoma Syndrome Following Chemotherapy


  • Mihoko Sasahara
  • Takashi Abe
  • Yoichi Otomi
  • Yumi Abe
  • Hiroaki Toba
  • Takayoshi Shinya
  • Hideki Otsuka
  • Masafumi Harada

Received Date: 27.05.2021 Accepted Date: 05.09.2021 Mol Imaging Radionucl Ther 2022;31(3):239-241 PMID: 36268930

Growing teratoma syndrome (GTS) is a condition in which poorly differentiated cells in a mixed-germ cell tumor (GCT) regress after chemotherapy, and the number of well-differentiated components increases. A 60-year-old man had an 8.0 cm mediastinal tumor with strong 18F-fluorodeoxyglucose (FDG) uptake [maximum standardized uptake value (SUVmax): 9.2], which was diagnosed as a GCT. After chemotherapy, serum alpha fetoprotein, beta-human chorionic gonadotropin, and tumor 18F-FDG uptake decreased (SUVmax: 3.9), but the tumor volume increased. The tumor was completely resected, and pathology confirmed the diagnosis of GTS. 18F-FDG positron emission tomography after chemotherapy reflects the proliferation of highly differentiated tumor components with poor 18F-FDG uptake.

Keywords: Growing teratoma syndrome, 18F-FDG PET, mediastinum, germ cell tumor


Informed Consent: Written informed consent of the patient was obtained.

Peer-review: Externally peer-reviewed.

Authorship Contributions

Surgical and Medical Practices: Y.O., Y.A., H.T., T.S., H.O., Concept: T.A., T.S., Design: M.S., T.A., Data Collection or Processing: M.S., Y.O., M.H., Analysis or Interpretation: M.S., M.H., Literature Search: M.S., T.A., Writing: M.S., T.A., Y.O.

Conflict of Interest: No conflict of interest is declared by the authors.

Financial Disclosure: The authors declare that this study received no financial support.


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