F-18 FDG PET scan of a metastatic pineoblastoma

A ti-year-old boy had obstructive hydrocephalus secondary to a partially ca lcified pineal mass visualized by brain CT, An MRI showed homogenous enhanc ement of a pineal gland tumor, a separate suprasellar mass, and the leptome ninges of the brain stem and cervical spinal cord. F-18 FDG PET scan showed increased glucose uptake in ail lesions. Biopsy of this pineal tumor indic ated pineoblastoma. The CT and MRI features of pineoblastoma are nonspecifi c and cannot distinguish the various types of pineal parenchymal tumors. F- 18 FDG PET scans could be helpful in classifying some difficult cases, beca use higher levels of F-18 FDG uptake would be expected in the malignant typ es because of increased glucose metabolism. PET scans could also be useful in determining the degree of malignancy in those tumors with Intermediate d ifferentiation.