Super Scan Caused by Parathyroid Carcinoma Observed Both in 18F-FDG PET/CT Scan and Tc-99m MDP Bone Scintigraphy

Super scan is a well-known finding described in skeletal scintigraphy characterized by uniform symmetrically increased radiopharmaceutical uptake by bones and consequently diminished renal parenchymal activity. Sy et al. hypothesized that the faint visualization of renal cortex in bone scintigraphy might be the result of increased uptake of radiopharmaceutical by pathologic bones and reduced phosphate excretion. The super scan on 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) has been observed in various conditions such as prostate cancer, lung cancer, renal adenocarcinoma, gastric cancer and primitive neuroectodermal tumor of the kidney. Herein we report the first case of super scan in a 68-year-old-woman with parathyroid carcinoma observed both in 18F-FDG PET/CT and Tc-99m methylene diphosphonate bone scintigraphy. There were extensive hypermetabolic lesions throughout the skeleton in 18F-FDG PET/CT. In contrast to the intense hypermetabolism of the skeleton; the liver, skeletal muscles of the limbs, mediastinum, bowel and especially the brain showed very low FDG uptake. Additionally, there was increased skeletal radiotracer uptake relative to soft tissue, and faint genitourinary tract activity in bone scintigraphy.