Positron emission tomography in the diagnosis and management of intracranial germ cell tumours.

Positron emission tomography (PET) with (18)F-fluorodeoxy-glucose indicates metabolically active tissue. When investigating enhancing intracranial tumours, we have suggested that PET positivity might suggest an intracranial germ cell tumour (IGCT). Here, we present a case with dicentric IGCT where PET was initially discordant between the lesions and where PET then became negative despite clearly aggressive clinical behaviour. A cautionary note is introduced with respect to the interpretation of negative (18)F-FDG PET when investigating enhancing intracranial lesions.