A 17-month-old girl was referred to Kyushu Cancer Center because of fever and pain on the right lower leg. The bone marrow examination at the sternum showed only 2% of blasts, whereas percent of blasts was 76% at the right anterior illiac crest, 92.8% at the right posterior, 66% at the left anterior and 0% at the left posterior. Surface marker study demonstrated that the blasts were non-reactive with majority of hematopoietic cells except My9. However, reactivity was found to several antineuroblastoma monoclonal antibodies such as A2B5, UJ13A and PI 153/3. Extensive survey for neuroblastoma failed to reveal any mass lesion. The patient was tentatively diagnosed as metastatic neuroblastoma. The patient responded to the treatment protocol of neuroblastoma and obtained complete remission for 5 months. However, she relapsed in the bone marrow again and was diagnosed as acute megakaryoblastic leukemia when the blasts were found to be reactive with Gp Ib, Gp IIb/IIIa and to have platelet peroxidase. The patient obtained second complete remission for 2 months with the treatment protocol of acute non-lymphocytic leukemia.
In this report we discussed about cross-reactivity of monoclonal antibodies of neuroblastoma with acute megakaryoblastic leukemia.
