A seven-year-old male underwent surgical resection and chemoradiation for average riskmedulloblastoma; twelve years later, the presence of a necrotic and infiltrative mass inthe same area and invading the brainstem prompted a subtotal resection. Pathology wasindicative of glioblastoma. He was then treated with concurrent temozolomide and usingbiologically effective dose calculations for gross residual tumor tissue in the brainstemas well as brainstem tolerance, a radiotherapy dose of 3750 cGy was chosen, fractionatedin twice-daily fractions of 125 cGy each. The gross tumor volume was expanded with a5 mm margin to the planning target volume, which was also judiciously subtracted fromthe normal brainstem. He completed his radiotherapy course with subsequent imagingfree of residual tumor and continued adjuvant temozolomide and remains under follow-up surveillance. This case underscores the rarity of metachronous medulloblastoma andglioblastoma, of which only five known cases heretofore have been described. We discussthe technicalities of radiotherapy planning in this patient, including common hurdles forradiation oncologists in similar patients.
- Brainstem tolerance
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging