Head and neck CT scan may be diagnostic of germinoma. Findings on CT scan suggestive of germinoma include hyperdensity compared to adjacent brain, pituitary stalk enhancement and thickening, and presence of calcification in the pineal region in the pediatric population.^[1]

• On CT the high cellularity results in a degree to hyperdensity compared to adjacent brain. Usually the mass enhances brightly.
• When in the floor of the third ventricle it is typically seen filling and expanding the infundibular recess and supraoptic recess.
• Imaging may however be normal initially and if the diagnosis is suspected clinically (e.g. idiopathic hypothalamic diabetes insipidus) then close followup is required to identify potentially very subtle abnormal pituitary stalk enhancement and thickening.
• In the paediatric population presence of calcification in the pineal region is a useful marker of an underlying tumor, as no calcification of the pineal is seen in children below the age of 6.5 and in only ~10% of children between 11 and 14 years of age.^[1]
• Germinomas show a homogeneous pattern and are hyperdense compared with brain tissue whereas nongerminomatous tumors NGGTS are irregular in shape, with edema, and are less dense than germinomas. Mature teratomas have mixed densities, with areas of calcification with distinct tumor margins and with large cysts.

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  Sagittal non contrast CT of germinoma of CNS^[2]
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  Axial non contrast CT of germinoma^[2]

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