Metabolic Superscan on ¹⁸F-FDG PET/CT in a Patient With Secondary Hyperparathyroidism

Superscan on PET/CT has been reported in the literature and mainly involved metastatic diseases. We report an uncommon case of a metabolic superscan on F-18-FDG PET/CT in a 56-year-old man with end-stage renal disease on hemodialysis who presented with secondary hyperparathyroidism. Parathyroid scintigraphy showed 2 lesions posteroinferior to both thyroid lobes, suggestive of parathyroid adenoma/hyperplasia. FDG PET/CT performed to assess for pulmonary nodules revealed diffuse FDG hypermetabolism involving the visualized skull, mandible, spine, sternum, ribs, and appendicular skeleton without corresponding CT lesion with no urinary radiotracer excretion, consistent with metabolic superscan secondary to renal osteodystrophy.