Histopathologic Modification in CNS Neuroectodermal Tumor: A Long Term Follow Up of a Clinical Case

Abstract

Background:Post-therapy differentiation in medulloblastoma (MB) is a rare event that has been described only in pediatric age. Methods:We describe the long term follow up of a case of medulloblastoma maturation after chemotherapy and radiotherapy in an adult MB patient. Results and Discussion:A 20-year-old patient was partially resected of a MB with ki-67 of 60%. DNA methylation-derived subgroup showed a molecular SHH profile. The patient received cranio-spinal tomotherapy (32.4 Gy in 18 fractions) with a boost on posterior fossa (23.4 Gy in 17 fractions, total dose: 55.8 Gy in 32 fractions). The MRI performed 2 months after revealed a minimal volumetric increase. The patient underwent 2 cycles of Cisplatin -Etoposide chemotherapy. The MRI showed stable disease. The patient underwent second surgery. The specimen showed neuronal cells showing various degrees of maturation from neurocytic to ganglion cells. No embryonal cells were present. Mitoses were absent. The residual lesion showed the post-therapy neuronal maturation of a medulloblastoma. DNA methylation-derived subgrouping confirmed the SHH profile. No other treatments were delivered after the second resection. To date the patient is still alive and free from progression 54 months after primary surgery. Conclusion:After a long term follow up, we showed that tumor maturation in an adult patient with medulloblastoma is characterized by a favorable outcome. Physicians should take into account that tumor maturation may occur and that its recognition is essential to define the prognosis and to manage adult patients.