A persistent epidural mass in a child with B-lineage ALL.

Epidural spinal cord compression as the initial presentation of acute lymphoblastic leukemia (ALL) is a rare and serious complication. Extramedullary disease is rarely reported in patients with ALL. The most common sites are bone, followed by soft tissue, skin and lymph nodes. We describe a child with common B-lineage ALL who presented with a mass in the spinal epidural space. She was initially treated with intrathecal chemotherapy and intravenous dexamethasone with total resolution of her clinical symptoms but a persistent epidural mass. An open biopsy of the residual epidural mass was performed 7 months after diagnosis. The histological examination did not reveal any tumor infiltration, only fibrosis. We conclude that a persistent epidural mass in patients with ALL may not indicate resistant disease and may require over a year for resolution, even when response to therapy is adequate.