Increased accumulation of TI-201 in monostotic Paget's disease of the patella - Evaluation with quantitative analysis

Monostotic Paget's disease of the patella was detected with Tc-99m MDP and Tl-201 scans, Diffuse intense uptake of MDP in the left patella was observe d on the blood-pool and late phases of the bone scan. Tl-201 imaging was pe rformed to differentiate a malignant process and showed diffuse marked accu mulation at the same site, Semiquantitative analysis of the patella region on both Tc-99m MDP and Tl-201 scans did not support a diagnosis of cancer. Radiographs showed the features of Paget's disease of the bone. Findings of a pathologic evaluation were compatible with the diagnosis of osteitis def ormans. This case represents the unusual skeletal involvement of monostotic Paget's disease of the bone in the patella, Tl-201 accumulation in the Pag et's lesion was suggested to be caused by increased metabolic activity of t he lesion but was not indicative of a malignant process.