Molecular Imaging with 18 F-FDG PET/CT and 99m Tc-MIBI SPECT/CT in Osteitis Fibrosa Cystica Generalisata.

Benign so-called "brown tumors" secondary to hyperparathyroidism are a rare diagnostic pitfall due to their impressively malignant-like character in various imaging modalities. We present the case of a 65-year-old male patient with multiple unclear osteolytic lesions on prior imaging suspicious for metastatic malignant disease. Eventually, findings of ¹⁸ F-FDG PET/CT staging and ^99m Tc-MIBI scintigraphy resulted in revision of the initially suspected malignant diagnosis. This case illustrates how molecular imaging findings non-invasively corroborate the correct diagnosis of osteitis fibrosa cystica generalisata with the formation of multiple benign brown tumors.