Pulmonary Leukostasis : Treatment When Cytoreduction Does Not Suffice

links.lww.com/JPHO/A171). Immunostaining was positive for vimentin and negative for S100, CK AE1/AE3, EMA, myogen, MyoD1, desmin, HHF35, CD34, CD45, MIC2, aSMA, and caldesmon. The Ki-67 labeling index reached approximately 30%. Fluorescence in situ hybridization using EWSR1 and FUS and reverse transcription polymerase chain reaction for ETV6-NTRK3, FUSDDIT3, EWS-DDIT3, HAS2-PLAG1, and COL1A-PLAG1 were all negative for specific gene rearrangements. Thus, he was diagnosed as having undifferentiated/unclassified STS. Four weeks after disease onset, vincristine, actinomycin D, and cyclophosphamide (VAC) were given every 3 weeks; however, VAC was switched to ICE [ifosfamide (60mg/kg for 5 d), carboplatin (13mg/kg for 2 d), and etoposide (3mg/kg for 5 d)] because the tumor grew rapidly and occupied his oral cavity. Nevertheless, the tumor continued to grow even 12 days following the start of ICE (Figs. 1B, H). The tumor was considered unresectable. We were unable to add cytotoxic drugs because of neutropenia. We avoided irradiation of the tumor section close to the brain considering his age. On the basis of the high expression of VEGFR1 and VEGFR-2 mRNAs in the tumor samples, we administered pazopanib suspension using a nasogastric tube at a dosage of 5mg/kg once daily when he was 5 months of age. We gradually increased the dosage to 20mg/kg over 6 courses of ICE every 3 or 4 weeks (Fig. 1) while checking the emergence of adverse events. Granulocyte colonystimulating factor was given if the absolute neutrophil count was below 500m/L. We observed significant reduction in the tumor size at 15mg/kg (Figs. 1D, J) and maximum reduction at 20mg/kg (Figs. 1E, F, K, L). Increased alanine aminotrasferase and pancreatic enzymes, diarrhea, skin rash, proteinuria, and hypertension could be doselimiting toxicities of pazopanib for children, in addition to anemia and neutropenia.3 However, we did not observe grade 3 or higher nonhematological adverse events apart from mildly increased asparatate aminotransferase/alanine aminotrasferase (Table 1). Notably, addition of pazopanib to ICE did not induce delayed recovery from cytopenia, in combination with granulocyte colonystimulating factor support. He underwent total resection of the tumor soon after completing pazopanib. There was no delayed wound healing during the postoperative period. Histopathologically, no residual tumor was found in the resected tissue. He has maintained complete remission for 19 months after the tumor resection. Pazopanib can cause growth plate toxicity in children.4 He had hardly grown since the start of chemotherapy (SD= 2.12); however, he caught up in height up to the normal range (SD= 1.35) by 12 months after treatment completion. A novel combination of pazopanib and ICE may be a possible treatment for infantile STS.