BACKGROUND: The lymphocytes including morphologically immature lymphoid cells are frequently increased in the marrow aspirates of children with neuroblastoma. We studied about the clonality of these lymphoid cells and its effects on the marrow involvement and prognosis of disease.
METHODS: We evaluated 30 marrow aspirates of 23 children with neuroblastoma from 1990 to 1998. We tested the immunoglobulin heavy chain gene rearrangement PCR for B cell clonality and T cell receptor gamma gene rearrangement PCR for T cell clonality tilth bone marrow specimens.
RESULTS: Younger children showed negative bone marrow involvement more than older children. In this group, the proportions of immature lymphoid cells and total lymphocytes were higher(3.4+/-3.2% vs. 0.8+/-1.9%, 31.3+/-17.0% vs. 14.7+/-12.0%). Immunoglobulin heavy chain gene rearrangements were present in 19/30 (64%) specimens and more frequently observed in negative marrow involvement cases. Seven cases with the proportions of total lymphocytes more than 30% showed significantly high long-term survival probability (P=0.05). Ten cases with B cell monoclonality showed the tendency of high long-term survival probability (P=0.13).
CONCLUSION: The increase of lymphocytes including morphologically immature lymphoid cells in the marrow aspirates of children with neuroblastoma were frequently observed in the children without marrow involvement of malignancy and closely related to B cell clonality. The increase of total lymphocytes and related B cell monoclonality may be one of possible explanations of good prognosis of children with neuroblastoma.

Keywords: Neuroblastoma, Bone marrow, Lymphocyte, B cell clonality, Prognosis