RONC-26. A CASE OF RADIATION NECROSIS OF THE CEREBELLUM 16 YEARS AFTER CHEMORADIOTHERAPY FOR MEDULLOBLASTOMA

BACKGROUND If new lesions are observed during follow-up of the malignant tumor after treatment, it is difficult to distinguish whether the tumor is a recurrent lesion, secondary cancer, or radiation necrosis of the brain. We have encountered a patient with symptomatic radiation necrosis of the cerebellum 16 years after treatment of medulloblastoma. CASE PRESENTATION: A 24-year-old man who had received a tumor resection and chemoradiotherapy for cerebellar medulloblastoma at the age of 8 presented with dizziness. For the past 16 years, there was no recurrence of the tumor. He subsequently underwent MRI scan, and T1-Gd image showed enhanced lesion in the right cerebellar peduncle. Cerebrospinal fluid cytology analysis was negative for tumor. We suspected tumor reccurence or secondary cancer, and performed lesion biopsy. The result of the pathological examination was radiation necrosis of the cerebellum. DISCUSSION: The interval of radiation necrosis of the brain and radiotherapy can vary from months to more than 10 years. So, whenever a new lesion is identified, radiation brain necrosis must be envisioned. According to guidelines in Japan, there is no absolute examination for discriminating tumor recurrence from radiation brain necrosis and diagnosis by biopsy may be required. CONCLUSION We experienced a case of symptomatic radiation necrosis of the cerebellum 16 years after treatment. In patients showing new lesion after long periods of time, the possibility of radiation necrosis to be considered.

The Role of Apparent Diffusion Coefficient in the Differentiation between Cerebellar Medulloblastoma and Brainstem Glioma

For certain clinical circumstances, the differentiation between cerebellar medulloblastoma and brainstem glioma is essential. We aimed to evaluate the role played by the apparent diffusion coefficient (ADC) values in the differentiation between cerebellar medulloblastomas and brainstem gliomas in children. The institutional review board approved this prospective study. Brain magnetic resonance imaging (MRI), including diffusion-weighted imaging (DWI) and ADC, was assessed in 32 patients (median age: 7.0 years), divided into two groups, a medulloblastoma group (group 1, n = 22) and a brainstem glioma group (group 2, n = 10). The Mann–Whitney U test was utilized to compare tumor ADCmax, ADCmin, ADCmean, and ADCsd values, and their ratios with the parenchyma values between the two groups. Receiver operating characteristic (ROC) curve analysis and the Youden index were used to calculate the cut-off value, along with the area under the curve (AUC), sensitivity, and specificity. The median ADCmax, ADCmin, and ADCmean values were significantly higher in group 2 than in group 1 (p < 0.05). The median ratios of ADCmin and ADCmean to the parenchyma were significantly higher in group 2 than in group 1 (p < 0.05). The ROC analysis showed that the AUC for the ADCmean ratio was the highest among these parameters, at 98.2%. The ADCmean tumor to parenchyma ratio was a significant and effective parameter for the differentiation between pediatric medulloblastomas and brainstem gliomas.

C-51 Long Term Neuropsychological Follow-Up of Radiation Induced Cognitive Decline (RICD) in Cerebellar Medulloblastoma

Objective We expanded upon an early case study suggesting long-term, sequential neurocognitive evaluation and academic interventions following pediatric cerebellar medulloblastoma. This five-year-old patient (now forty) has indeed undergone lifespan assessment and clearly benefitted from appropriate interventions to date. Method This left-handed, white, male is status post (s/p) gross total resection and whole brain radiation. In adulthood, he developed radiation necrosis with hemorrhage and refractory seizures (s/p right temporal lobectomy). More recently, radiation induced bilateral parietal meningiomas were identified (s/p gamma knife). Results We analyzed cognitive, medical/oncological, imaging and interventional data at developmentally meaningful time points and found consistent declines in intellectual skills and cognitive function spanning attention/concentration, processing speed, visual perceptual/organization and visually based learning/memory; however, we noted stabilization and even improvement in important areas. Areas of age-appropriate functioning were noted in expressive vocabulary, verbal abstract reasoning, delayed verbal memory, and problem-solving, among others. Conclusions Although some studies have addressed long-term outcomes in pediatric medulloblastoma, we provide a unique perspective to the literature by documenting serial neurocognitive findings in addition to interventions across the lifespan. Our findings suggest that appropriate academic interventions/neurocognitive rehabilitation strategies are in fact meaningful at the individual level and propose that a focus on strengths can improve outcomes. We propose that this previously recommended model of assessment/intervention truly become the available standard of care in all pediatric oncologic populations.