What is the most likely diagnosis for the findings on these scans of a 14 years old boy?
- Midbrain glioma
- Pineal cyst
- Pineal region germinoma
- 3rd ventricle ependymoma
- Corpus callosum glioblastoma
Congratulations to those who chose pineal region germinoma. The young age of this patient, predominantly solid lesion with small cystic component, contrast enhancement, and mass effect on adjacent structures (tectal plate, cerebellum and the cerebral aqueduct) favor this diagnosis. Simple pineal cyst does not have a solid component and usually does not enhance.
Midbrain glioma would be present anteroinferior to the tectal plate and may cause edema and ballooning of the brainstem.
3rd ventricle ependymoma would be intraventricular, show more avid enhancement on contrast and would not typically extend to cerebellum posteriorly. It would commonly cause significant dilatation of the frontal horns of lateral ventricle.
Corpus callosum glioblastoma usually appears like butterfly lesions, has heterogenous contrast enhancement and surrounding edema and is more common in middle ages.