Demonstration of Diffuse Leptomeningeal Metastasis in a Treated Case of Medulloblastoma With F-18 FDG PET/CT

Abstract

A 20-year-old man diagnosed as a case of desmoplastic cerebellar medulloblastoma had undergone shunting of the lateral ventricles and resection of the mass followed by postoperative irradiation to the entire neuraxis. There was evidence of residual disease in the posterior fossa on craniospinal MRI for which he had undergone cranial radiation and adjuvant chemotherapy. Two serial cranial MRI's (4 months apart) were done following this and though the lesion in the posterior fossa remained essentially the same with no evidence of progression the patient had a general decline in his ability to function and he was sent for a FDG-PET/CT study to evaluate for recurrent disease. The study revealed abnormal FDG uptake along the entire length of the thecal sac from the cervical to the lumbosacral level suggesting the possibility of metastasis. Spinal MRI with gadolinium contrast confirmed diffuse leptomeningeal metastasis. Thus FDG-PET/CT is a useful tool to evaluate for metastasis in medulloblastoma.