Radiographic features of RDD. (A) Gadolinium-enhanced coronal T1-weighted magnetic resonance imaging (MRI) demonstrates a dural-based lesion at the base of the right frontal lobe (blue arrow). (B) Patchy enhancing lesions in the brainstem on gadolinium-enhanced axial T1-weighted MRI (green arrow). (C) Gadolinium-enhanced axial T1-weighted MRI demonstrates lesions in the bilateral cavernous sinuses and Meckel’s cave (red asterisks) as well as the left orbit (red arrow), with resulting proptosis. (D) Axial fused [¹⁸F]fluorodeoxyglucose (FDG)–positron emission tomography (PET)/computed tomography (CT) demonstrates a hypermetabolic dural-based paraspinal mass with involvement of the osseous elements of the thoracic spine with foraminal extension. (E) Response to 12 weeks of 1 mg/kg per day of prednisone is demonstrated, with near resolution of hypermetabolism and regression of the tumor. (F) Partly T2-weighted bright-blood image shows an oval mass (black arrow) in the left atrium (LA) arising from the central part of the heart at the atrioventricular junction. LV, left ventricle; RA, right atrium; RV, right ventricle.