Neurosyphilis manifesting as a focal mass lesion: computed tomographic and magnetic resonance imaging features--case report.

The computed tomographic (CT) and magnetic resonance (MR) imaging findings in a middle-aged male with cerebral syphilis are described. He presented with convulsive seizures and focal neurological deficits. A CT scan revealed a slightly enhanced, low-density mass in the left parieto-occipital region. MR imaging showed low intensity on T1-weighted images and high intensity on T2-weighted images. He was initially diagnosed as having a low-grade glioma. However, intraoperative histological examination of a small surgical specimen revealed no tumor cells but heavy infiltration of inflammatory cells in the meninges and cerebral parenchyma. Immunostaining for Treponema organisms by the peroxidase-antiperoxidase method was positive. Although the clinical and radiological findings are nonspecific, neurosyphilis should be considered in any patient in whom a nonspecific mass lesion is demonstrated by CT and MR imaging.