NI-05 CLINICOPATHOLOGICAL ANALYSIS AND METHIONINE PET ANALYSIS IN PATIENTS WITH GLIOMATOSIS CEREBRI

OBJECTIVE: Gliomatosis cerebri (GC) was defined as the tumor infiltrating into more than three lobes in WHO2007, but was deleted in WHO2016 because they include genetically heterogeneous tissues. However, we often encounter the cases with strongly invasive glioma. Then, we clinically analyzed the cases of GC. PATIENTS AND METHODS: Seven cases (five men, median age: 57 years (23-89y)) diagnosed as GC in our hospital were included. Data of methionine-positron emission tomography (Met-PET), IDH and p53 mutation, MIB1-labeling index (LI) by immunohistochemistry were searched. We compared the accumulation areas of the Met-PET with the hyperintensity area (T2/FLAIR-high) and gadolinium-enhanced area on the MRI. We also examined a biopsy method, sites and a treatment regimen and analyzed overall survival (OS) and progression-free survival (PFS). RESULTS: The primary symptoms were disorientation in five, epileptic seizure and abnormal vision were two, respectively. The largest lesion area with the image was T2/FLAIR-high, followed by Met-PET and Gd in all. The surgical methods were stereotactic biopsy (2), navigation-guided biopsy (2), endoscopic biopsy (1), and craniotomy (2), The average of tumor/normal ratio in Met-PET was 2.92 (1.97–5.0). The pathological grade was diagnosed as Grade III in 4 and Grade II in 3. IDH1R132H was negative in all, p53 was positive in 5, and an average of MIB-1LI was 12% (2–35). The radiotherapy was performed in 6 cases, and, temozolomide was given to all, and bevacizumab was in 3. Six patients died of a tumor. Median PFS and OS were 8mos and 16.5mos, respectively. CONCLUSION: Because the GC cannot expect improvement by surgery, it is necessary to obtain the pathological diagnosis by a quick and correct biopsy, and the neurologic deterioration by the biopsy technique should be avoided. The Met-PET suggesting the highest grade site was useful for the plan of the biopsy site.