ABSTRACT
The authors report the clinical course of a 3-year-old boy with stage 4 neuroblastoma (NB) complicated by hemophagocytic lymphohistiocytosis (HLH) immediately after the start of chemotherapy. The NB responded very well to the chemotherapy, but the patient developed high fever on the 2nd day, and was diagnosed as having HLH of the 7th day of chemotherapy. No infections were demonstrated, and massive tumor cell destruction resulting from the rapid effect of chemotherapy was thought to be a cause of systemic cytokine response, resulting in HLH. Methylprednisolone pulse therapy was effective for the HLH, which did not recur thereafter. HLH should be recognized as a serious adverse event during chemotherapy for advanced NB that has a large malignant cell load.