Neuroblastoma during acute lymphoblastic leukemia in remission.

Neuroblastoma was diagnosed in a child after a 20-month remission of a pre-B acute lymphoblastic leukemia (ALL). Clumps of atypical cells suggestive of neuroblastoma were seen in the bone marrow. They were positive for monoclonal antibody (MoAb) UJ13A (neuroblastoma cells) and negative for MoAb T29/33 (anti-leucocyte common antigen CD45) with immunocytochemical staining. A right paravertebral mass displacing the kidney was demonstrated by abdominal echotomography, and serum vanilmandelic acid was slightly increased. Despite specific chemotherapy against neuroblastoma and after a transient clinical improvement, the patient died 7 months later of disseminated disease. Immunocytochemical staining on cells frozen at diagnosis of leukemia with MoAb UJ13A and T29/33 was unable to demonstrate neuroblastoma cells and showed the pattern usually observed in leukemia (UJ13A- and T29/33+).