Radiographic and neuro-SPECT imaging in an immature third ventricle teratoma: case report.

We report a case of an immature teratoma of the third ventricle, which was preoperatively thought to be a choroid plexus papilloma. The diagnosis was made by biopsy since the radiographic (CT, MRI), angiographic and scintigraphic findings ([99mTc]pertechnetate, 99mTc-DTPA, 99mTc-HMPAO brain SPECT) were nonspecific. Disruption of the blood-brain barrier is the mechanism for radionuclidic and contrast tumoral uptake and is demonstrated by marked contrast enhancement on CT and focal concentration on [99mTc]pertechnetate and 99mTc-DTPA images. No suppression of [99mTc]pertechnetate tumor uptake was observed following the administration of potassium perchlorate. Increased concentration of tumor protein is suggested by the increased signal on the T1-weighted magnetic resonance images and high [99mTc]pertechnetate uptake. The tumor's detection on the 99mTc-HMPAO brain SPECT was due to its intraventricular location. A number of potential mechanisms for brain tumor localization of 99mTc-HMPAO are discussed.