Immunodiagnosis and immunotherapy of childhood malignancies

Undifferentiated acute leukemia and lineage infidelity (difficulties in classification and management)

The acute leukemias have been considered to represent a clonal expansion of a malignant transformed hematopoietic progenitor cell with adherence to either the myeloid or lymphoid lineage--"lineage fidelity." Lineage fidelity has been challenged by the demonstration of lineage switching or mixed-lineage leukemias. We describe a 7 year old male who presented with undifferentiated acute leukemia and nasopharyngeal and cervical masses. His blasts had the morphologic appearance of myeloblasts (FAB M1) and were positive solely for the myeloid antigen CD15. He entered a complete remission (CR) with acute nonlymphocytic leukemia therapy. At first relapse he had evidence of mixed-lineage leukemia with B-cell lymphoid and myeloid phenotypes. He again relapsed from a second CR with Burkitt-cell leukemia. Cytogenetic findings showed a consistent 14q+, 17p+ abnormality in the blasts and nasopharyngeal mass. The t(8;14) associated with Burkitt's lymphoma was found in the mass tissue only following passage in the nude mouse. Our patient demonstrates that limitations still exist in our ability to classify acute leukemia. That leukemic transformation occurred in a multipotential progenitor cell leading to undifferentiated leukemia at diagnosis and/or that chemotherapy can influence the genetic programs of leukemic cells leading to the evidence of mixed-lineage leukemia and lineage switching is supported.

Early onset acute orbital involvement in childhood acute lymphoblastic leukemia

A 5-year-old girl with acute lymphoblastic leukemia undergoing induction chemotherapy experienced acute proptosis while agranulocytotic and febrile. Orbital biopsy showed leukemic infiltration, and complete resolution was achieved with local irradiation and chemotherapy. Early onset orbital involvement is highly unusual in acute lymphoblastic leukemia. In the setting of agranulocytosis and fever, rapidly enlarging intraorbital masses require urgent ophthalmologic attention. Immediate biopsy is indicated to distinguish between several treatable conditions including opportunistic infection, hemorrhage, and neoplastic infiltration.