A Rare Case of Retroperitoneal Teratoma Mimicking Paraganglioma on Multimodality Imaging

A 28-year-old woman incidentally palpated an asymptomatic abdominal mass. Contrast-enhanced MRI revealed a retroperitoneal mass with arterial phase hyperenhancement and mild delayed-phase washout, raising suspicion for paraganglioma. 18F-FDG PET/CT showed a soft tissue mass with mild and heterogeneous 18F-FDG uptake, while 68Ga-DOTATATE PET/CT revealed intense uptake, further supporting the presumptive diagnosis of paraganglioma. However, postoperative pathology confirmed a teratoma containing thyroid tissue with positive somatostatin receptor (SSTR) 2 and SSTR 5 expression, which may explain the false-positive uptake on 68Ga-DOTATATE. This case may provide a critical differential diagnostic consideration in retroperitoneal masses with high 68Ga-DOTATATE uptake.