Leukostasis is a severe complication of hyperleukocytosis secondary to childhood leukemia. Although increased leukocyte counts tend to induce the occurrence of leukostasis, additional factors may be involved in the pathogenesis of leukostasis, such as the size and deformability of blast cells, and the expression levels of adhesion molecules. Such factors might explain why the incidence of leukostasis differs among acute myeloid leukemia, acute lymphoblastic leukemia, and chronic myeloid leukemia. Leukostasis is associated with an increased risk of early death, and is considered to involve blast cell aggregates and thrombi in the circulation, inducing tissue hypoxia. The central nervous system and lungs are the most common sites for leukostasis. Although the pathological definition of leukostasis is clear, its clinical diagnosis is rarely made with high confidence. Because leukostasis is an oncological emergency, leukapheresis may prove beneficial in cases manifesting severe leukostatic symptoms, and immediate initiation of chemotherapy for this chemosensitive disease should not be delayed.

The outcomes of hepatoblastoma (HB) have been improved by the use of intensive combination chemotherapy, surgical resection, and liver transplantation. However, unresectable cases and cases involving residual metastasis have a poor prognosis. Although such patients are treated with high-dose chemotherapy, its efficacy against HB remains controversial. Here, we retrospectively analyzed the outcomes of hematopoietic stem cell transplantations (HSCTs) in 136 HB patients (total number of HSCTs: 162) on the basis of the nationwide registry data of the Japan Society for Hematopoietic Cell Transplantation. At the time of the HSCT, 70 patients were in complete remission (CR), 80 patients were in non-CR, and 12 patients were in an unknown state. Almost all combinations of chemotherapy were categorized as follows: HiMEC (CBDCA, VP16, L-PAM) (n=51) or TEPA+L-PAM (n=43). The 5-year overall survival (OS) and event-free survival (EFS) rates were 63.7% and 50.3%, respectively. The 5-year OS and EFS rates of the patients who received HSCT while in the CR period were 80.2% and 62.4%, whereas those of the patients who received HSCT while in a non-CR state were 49.8% and 38.4%, respectively (p<0.05). The prognosis of the patients who received HSCT in a non-CR period was almost the same as that in previous reports. HSCT for HB has become less common as the survival rate of HB patients has been improved with the use of aggressive surgical interventions for lung metastases and liver transplantation. Therefore, the efficacy of HSCT should be evaluated as a clinical trial for patients who are at high risk of recurrence in the near future.

We report a case of primary Burkitt lymphoma of the appendix presenting as acute appendicitis. A 16-year-old male was admitted to our hospital because of abdominal pain of 9-days’ duration shifting to the right lower quadrant, vomiting, and fever. He was clinically diagnosed as having acute appendicitis, and appendectomy was performed. He was histopathologically diagnosed as having appendiceal Burkitt lymphoma. PET-CT showed FDG uptake in the enlarged mesenteric lymph nodes, and we determined that he had stage III lymphoma. Two months after the operation, he started to receive four courses of chemotherapy based on the LMB/FAB96 protocol and he was in complete remission for 18 months from the time of diagnosis. Appendiceal lymphoma is reported to develop more insidiously than nontumoral acute appendicitis, and to show extended dilatation of the appendiceal lumen with its vermiform morphology maintained. When these findings are seen in patients with appendicitis, lymphoma should be ruled out.

The standard treatment for B-cell non-Hodgkin Lymphoma (B-NHL) in children consists of short-course highly intensive chemotherapies. However, little is known about how the treatment should be modified for those with acute kidney injury (AKI). Here, we report the case of a one-year-old boy with abdominal Burkitt lymphoma, who presented with severe AKI. We administered rituximab-combined chemotherapy, with methotrexate (MTX) omitted because it is potentially nephrotoxic, in induction therapy. Because of the remarkable tumor reduction and recovery of renal function, the full dosage of MTX was administered with rituximab in the following courses. Complete remission was achieved and no significant adverse events occurred during treatment. His renal function remains normal and he is alive without relapse at one year after the disease onset. The addition of rituximab may be a reasonable choice in treating pediatric B-NHL, when a key cytotoxic drug has to be reduced or omitted owing to severe AKI.

We report a case of refractory secondary hemophagocytic lymphohistiocytosis (HLH) manifesting severe liver dysfunction following Kawasaki disease (KD-HLH). A 1-year-old girl admitted for her first KD episode experienced remission after initial treatment with intravenous immunoglobulin (IVIG) and prednisolone (PSL). Symptoms similar to recurrent KD, including severe liver dysfunction, anemia, thrombocytopenia, and elevated soluble interleukin 2 receptor (sIL-2R), occurred 28 days after the initial treatment, fulfilling five of the eight HLH criteria. Her condition deteriorated rapidly. She required intensive care for multiorgan failure. Steroid pulse therapy was followed by dexamethasone, and IVIG was readministered. Cyclosporine A was also administered owing to worsening symptoms and increased sIL-2R levels. She is currently well without sequelae.

Some previous reports of cases of KD-HLH mentioned severe manifestations and acute exacerbation such as those in our case. Early recognition and treatment are important when atypical KD manifestations occur or when the patient fails to respond to conventional KD treatment.

Infantile neuroblastoma is a curable disease characterized by frequent spontaneous regression, and a localized neuroblastoma in an infant is sometimes carefully observed with a “wait and see” strategy. We present the case of an infant with a localized neuroblastoma in which two distinct clones were cytogenetically determined. The infant was male and diagnosed as having a localized cystic neuroblastoma of the right adrenal gland. During a follow-up period with careful monitoring, the tumor once regressed, but later showed progression with a growing solid mass after 6 months. The tumor was finally resected when he was 11 months old. Interestingly, DNA ploidy analysis revealed 2 different hyperdiploid peaks within a single tumor, suggesting heterogeneity. This hypothesis was supported by histopathological findings: both well-differentiated and poorly differentiated segments were observed in the resected tumor. It should be noted that even low-grade neuroblastoma may have tumor heterogeneity.

Hemophilia is the most frequent disease among congenital coagulation disorders, but distinct guidelines for delivery in hemophilia carriers have not been established. We report the case of a neonate presenting with cerebellar hemorrhage induced by stress during vaginal delivery. The mother’s brother has severe hemophilia A, with confirmed inversion of intron 22 of the factor VIII gene. The grandmother and mother were definitive carriers. The subject was identified as a boy by fetal ultrasound; therefore, vacuum extraction was prohibited. He was born by full-term normal vaginal delivery. No subcutaneous hemorrhage was observed, and brain ultrasonography findings were normal. However, enlargement of the bilateral ventricles was confirmed by ultrasonography 19 h after birth, and CT revealed a 40×30 mm² hematoma in his right cerebellar hemisphere. He was conservatively treated with a factor VIII concentrate. No further enlargement of the hematoma occurred and it was gradually absorbed. Currently, he is 2 years old and has no neurological deficits.

Langerhans cell histiocytosis (LCH) is a clonal neoplastic proliferation of abnormal Langerhans-like cells. Bone is the most commonly involved site, while isolated soft tissue lesion involvement is rare. We report a case of a 5-year-old girl diagnosed as having multisystem LCH with thoracic spine lesions, a pleural lesion, and multiple soft tissue lesions at the posterior neck, which lacked continuity to any bone lesion. After administration of antibiotics because of a suspicion of subcutaneous abscess and purulent spondylitis, fever, and posterior neck swelling were ameliorated. Because her symptoms were ameliorated only with antibiotics, we were unable to obtain her parents’ consent to administer anticancer chemotherapy. LCH recurred twice in the following 9 months, and each time, her symptoms were ameliorated by the administration of antibiotics alone. Finally, she received chemotherapy and attained complete remission that lasted for four years. This case may be important for understanding the complex nature of LCH, considering the rareness of a soft tissue lesion and the temporary efficacy of antibiotics.