DOI: https://doi.org/10.36347/sjmcr.2026.v14i10.035

Pages: 2269-2273

Background: Medulloblastoma is a malignant embryonal tumor occurring predominantly in children. Extraneural dissemination is rare, particularly in adults, with skeletal and bone marrow metastases representing an uncommon and aggressive pattern of relapse. Case presentation: We report a 27-year-old man with a posterior fossa non-WNT/non-SHH medulloblastoma, CNS WHO grade 4, treated with surgical resection, carboplatin–etoposide chemotherapy, and craniospinal irradiation (36 Gy with an 18-Gy boost). Complete radiological regression was initially achieved. Five months after chemotherapy, the patient developed recurrent severe epistaxis and pancytopenia. Imaging revealed diffuse mixed osteolytic and osteosclerotic skeletal lesions associated with suspected local intracranial recurrence. Bone marrow biopsy confirmed metastatic medulloblastoma. Temozolomide was planned but could not be initiated because of persistent severe thrombocytopenia and hemorrhagic manifestations despite transfusional support. The patient died in April 2025. Conclusion: Diffuse skeletal and bone marrow metastases are a rare and aggressive manifestation of adult medulloblastoma. Unexplained cytopenias should raise suspicion of marrow involvement, which may reveal systemic relapse and preclude further systemic therapy.