MEDB-48. Infant medulloblastoma - SHH subtype – with residual disease. To treat or not to treat

Abstract

Management of infant medulloblastoma remains a challenge. Front-line chemotherapy can successfully avoid radiation in low-risk infant medulloblastoma. Patients that do relapse can be salvaged long-term with radiotherapy. We report 4 cases of infants with medulloblastoma treated with chemotherapy (HIT2000 protocol) with residual or progressive disease. RESULTS: Four cases of infant medulloblastoma, all MBEN/nodular desmoplastic SHH type B, p53 WT, no MYC / MYCN amplification. CASE 1: 16 month old girl, metastatic lesions in the cerebellum and meningeal enhancement. Germline SUFU mutation. After 3 cycles of chemotherapy MRI showed more enhancement of the residual disease. To inform management, second look surgery was performed. Pathology showed fibrous tissue only, no malignant cells. The child continues to be treated as per HIT2000. CASE 2: 5 month old girl, metastatic lesions in the cerebellum. Germline SUFU mutation. 2 months after end of treatment, MRI demonstrated progression of cerebellar lesion. Surgical resection was performed, pathology showed differentiated mature neuronal tissue. No further treatment; remains in remission 1 year after suspected progression. CASE 3: 27 month old boy, metastatic lesions in cerebellum. Germline SUFU mutation. 1 month post-completion of treatment progressive prominent nodules along the cerebellum and cerebellar leptomeningeal enhancement. Biopsy not feasible so close MRI surveillance was initiated. MRI remains stable 1 year after suspected progression. CASE 4: 30 months old boy, non-metastatic disease. Complete resection. No germline mutation. End-of-treatment MRI showed subtle new intraspinal leptomeningeal deposits and a suspicious left optic tract nodule, subsequent MRI 8 weeks later showed clear progressive disease. Unfortunately, the child died before radiotherapy could be delivered. CONCLUSION: Salvage radiotherapy for infants with medulloblastoma who progress following chemotherapy treatment can be life-saving but risk significant cognitive impairment. Differentiation of medulloblastoma following radio/chemotherapy has been reported. We recommend considering tissue confirmation prior to embarking on further treatment for suspected relapse.