Extramedullary relapse of acute myeloid leukemia presenting as an epidural spinal mass with vertebral and acetabular leukemic involvement: A case report.

Extramedullary relapse of acute myeloid leukemia (AML) refers to the infiltration of leukemic cells into tissues outside the bone marrow and is a rare occurrence involving central nervous system, particularly following allogeneic stem cell transplantation. We report a rare case of extramedullary relapse of acute myeloid leukemia (AML) presenting as a thoracic epidural mass with additional multiple vertebrae and acetabular leukemic involvement in a 28-year-old male, two years postallogeneic stem cell transplantation. The patient presented with progressive lower extremity weakness and paresthesia. Imaging revealed an extensive epidural mass causing spinal cord compression, along with increased 18F-fluorodeoxyglucose uptake in the mass, multiple vertebrae and the left acetabulum. Surgical decompression and biopsy of the spinal epidural mass confirmed leukemic infiltration. To our knowledge, this is the first reported case of extramedullary AML relapses simultaneously involving the epidural space, multiple vertebrae and acetabulum.