Coexistence of T-cell lymphoblastic lymphoma and myelodysplastic syndrome in a child.

A 10-year-old girl presented with T-cell lymphoblastic lymphoma of the mediastinum coexisting with myelodysplastic syndrome. Bone marrow examination showed trilineage dysplasia with no evidence of lymphoma cells. Intensive chemotherapy led to a marked reduction in the mediastinal tumor, but no improvement in bone marrow findings. Unrelated cord blood transplantation was performed, resulting in completely chimeric bone marrow cells. A possible explanation for the simultaneous presentation of T-cell lymphoblastic lymphoma and myelodysplastic syndrome is that transformation occurs in pluripotent stem cells differentiating into myeloid and lymphoid cells.