Images below require Macromedia's Flash Player to view

Neuroradiology Case of the Week

Case 91

Ravinder Sidhu MD, Henry Wang MD, PhD, Sven Ekholm MD, PhD,
and P-L Westesson MD, PhD, DDS

Clinical Presentation: A 46-year old male underwent head CT examination as a sequale of head injury. An incidental finding was noted which is discussed below.

Radiological Findings:  Non-contrast enhanced head CT showed a well-defined homogeneously hyperdense mass of 2x2 cm size located in the anterior portion of the third ventricle (Fig.1). The mass revealed hyperintense signal on T1-weighted and hypointense signal on T2-weighted MR image (Figs. 2A & B).

Diagnosis: Colloid cyst

Discussion: Colloid cysts are rare non-neoplastic lesions of neuroectodermal origin. They are typically located in the anterior third ventricle, positioned between the columns of the fornix. They account for 0.5-1% of all intracranial tumors seen commonly in adults, without any sex predilection. The most common presenting symptom is headache followed by vertigo, memory deficits and diplopic. Sudden interruption of CSF circulation with coma and death has also been reported.
     On non-contrast enhanced CT, approximately two-thirds of cysts are seen as homogeneously hyperdense compared to brain parenchyma, and one-third are isodense. Rim enhancement after contrast administration may be seen which is likely to represent the capsule.
     On MR imaging, the most common appearance is hyperintense on T1-weighted and hypointense on T2-weighted sequences. Occasionally, the colloid cyst may have a variable appearance due to intracystic cholesterol and protein components.

References:

1. Socin HV, Born J, Wallemacq C, Betea D, Legros JJ, Beckers A. Familial colloid cyst of the third ventricle: neuroendocrinological follow-up and review of the literature. Clin Neurol Neurosurg. 2002; 104:367-370.
2. Armao D, Castillo M, Chen H, Kwock L. Colloid cyst of the third ventricle: Imaging –pathologic correlation. AJNR Am J Neuroradiol. 2000; 21:1470-1477.