Back pain is often reported in children undergoing cancer treatment, but is not typically a presenting symptom. Spinal cord compression secondary to myeloid sarcoma (chloroma) has been described, although is rare in children. We describe a 10-year-old child who presented with thoracic back pain, which progressed quickly to complete paraplegia prior to the diagnosis of myeloid leukemia. Neuroimaging demonstrated an extradural mass at level T6 to T10, requiring emergent laminectomy and posterior decompression. Histopathology of this lesion was consistent with myeloid sarcoma while peripheral blood and bone marrow examination documented acute myeloid leukemia. He underwent treatment with multiagent chemotherapy and remains in remission. Increased recognition of ominous symptoms that suggest underlying pathology or signs of cord compression will lead to earlier diagnosis and, ultimately, minimize neurologic morbidity.