Extensive vertebral compression fractures as the initial manifestation of childhood B-cell acute lymphoblastic leukemia despite limited peripheral blood abnormalities: a case report

Background Musculoskeletal manifestations may appear before hematologic abnormalities in childhood acute lymphoblastic leukemia (ALL), making diagnosis difficult. Extensive vertebral compression fractures involving the cervical, thoracic, and lumbar spine as the first sign of ALL are very rare, particularly when peripheral blood abnormalities are limited and circulating blasts are absent. Case presentation We report a 5-year-old boy who presented with severe back pain and inability to walk after minor trauma. The initial lumbar computed tomography (CT) was reported as showing no definite vertebral fracture, but whole-spine magnetic resonance imaging (MRI) showed diffuse bone marrow infiltration with extensive pathological compression fractures involving the cervical, thoracic, and lumbar vertebrae. Peripheral blood tests showed leukopenia and neutropenia without circulating blasts, which contributed to the initial diagnostic uncertainty. Bone marrow examination confirmed common B-cell acute lymphoblastic leukemia with high hyperdiploidy and a KRAS p.G13D mutation. After induction therapy according to the South China Children's Cancer Group (SCCCG)-ALL-2023 protocol, his back pain was greatly relieved, he regained independent ambulation, and flow cytometric and molecular measurable residual disease (MRD) assessments became negative. Conclusion Extensive vertebral compression fractures can be an early manifestation of childhood ALL, even when circulating blasts are absent and peripheral blood abnormalities are limited. Children with persistent axial skeletal pain or unexplained vertebral compression fractures should be evaluated for hematologic malignancy, especially when their symptoms are more severe than expected from routine imaging or peripheral blood findings. Early whole-spine MRI and timely bone marrow examination may help establish the diagnosis and avoid unnecessary delay.