Background: Myeloid sarcoma (MS) is a rare solid tumour made of myeloblasts or immature myeloid cells in an extramedullary site or in bone, associated with systemic hematologic neoplasms. When they occur in the brain parenchyma, they can often be misdiagnosed. Methods: The authors report a case of a 4-year old boy 6 months out of remission from AML, presenting with a short history of headaches and vomiting, and found to have a heterogenous contrast-enhancing lesion in the right cerebellar hemisphere, with differential diagnosis of myeloid sarcoma, astrocytoma, medulloblastoma and ATRT. Preliminary diagnosis was made flow cytometry from an intraoperative biopsy. The patient had a long course of chemotherapy and radiation, but eventually died from the systemic burden of his AML. Results: The authors present a literature review on 178 published cases of CNS myeloid sarcomas, and their radiological presentation and the basis of immunohistochemical and pathological diagnosis is discussed. Conclusions: Diagnosis rests on a combination of immunohistochemistry and histopathology of biopsied tissue. Surgical resection is controversial, especially given the efficacy of chemotherapy and radiation, and prognosis remains unclear. As with all uncommon and rare clinical entities, further investigation is warranted to determine prognosis and optimal management of CNS myeloid sarcomas.