Organizing intracerebral hematoma mimicking a recurrent brain tumor on FDG-PET.

A man underwent resection of low-grade astrocytoma, followed by radiation therapy at the age of 14 years old. He had been followed up for 33 years with no finding of recurrent disease on brain images until the most recent CT and MRI scans showed a mass at the postoperative site in the left parieto-occipital lobe. 18F-FDG PET/CT showed increased uptake in the mass. Resection was conducted, and microscopic examination of the whole mass demonstrated an organizing hematoma. A provisional diagnosis of organizing hematoma should be considered, along with other benign and malignant causes of increased FDG uptake.