Secondary syphilis: An unusual cause of osteolytic lesion diagnosed by 99mTc-MDP SPECT and presenting features

Abstract

Herein, we present the case of a 68-year-old woman complaining of pain of the right knee, which was initially misdiagnosed by plain radiography as fracture on inner right tibia plateau but was finally clarified as osteolytic lesion secondary to syphilis affecting the whole right knee. The final diagnosis was made based on the valuable findings from bone scanning, which allows for imaging of abnormalities with much larger extent, a scale that is out of the examination capacity of plain radiography. Bone scanning was employed in this case, coupled with the use of 99mTc-MDP, to assess abnormal bone metabolism at the whole right knee next to the tibia plateau. The imaging results illustrated the diverse features of bone involvement of secondary syphilis, including periostitis, osteolysis as well as osteomyelitis, occurring together or in isolation.