Separation of chromatids of all mitotic chromosomes, here called total premature chromatid separation (total PCS), was observed in 67 to 87.5% of repeated cultures of peripheral blood lymphocytes from two unrelated infants. Also noted was a variety of mosaic aneuploidies, especially trisomies, double trisomies, and monosomies, to be called mosaic variegated aneuploidy. The infants both showed severe pre- and postnatal growth retardation, profound developmental retardation, uncontrollable seizures, severe microcephaly, hypoplasia of the brain, Dandy-Walker anomaly, abnormal facial appearance, and bilateral cataract. Patient 1, a girl, in addition had a cleft palate, multiple renal cysts, and Wilms tumor of the left kidney. Whereas patient 2, a boy, had ambiguous external genitalia. They both died within 2 years of age. In the two families of the infants, their parents and three other members showed 2.5 to 47% lymphocytes with total PCS but without mosaic variegated aneuploidy or phenotypic abnormalities. Another 10 relatives studied showed 0 to 1% cells with total PCS and so were judged negative for the total PCS trait. It was deduced that the total PCS trait in the two families was transmitted in an autosomal-dominant fashion, and the two affected infants were homozygous for the trait.

Patients in the lower-risk groups with embryonal-type tumors had poorer outcomes in this retrospective study. The better outcome of patients in the high-risk group is apparently due to the outstanding results obtained with an HDC regimen in a single institution. These results suggest that there is a need for: (1) a standard therapy, (2) a rapid central pathology review including a chimera gene analysis for the lower-risk group, and (3) evaluation of the efficacy of the high-dose regimen for the high-risk group in Japan.

The prognosis for thoracic neuroblastoma has been documented as good, but the reasons have not been elucidated. We reviewed our experience of patients with thoracic neuroblastoma who were treated over the past decade. Among 102 patients treated for neuroblastoma at our hospital between December 1987 and June 1997, 20 patients had thoracic neuroblastoma (stage 1: nine, stage 2: five, stage 3: three, stage 4: three). Tumor characteristics and survival rate were compared between thoracic and nonthoracic neuroblastoma. The surgical margin was positive in 13 of the 20 patients with thoracic neuroblastoma. However, local recurrence was observed in only one patient who later underwent complete resection. All patients survived 4-14 years of follow-up. Among those over 1 year old, thoracic neuroblastoma was detected at an earlier stage than in their nonthoracic counterparts (stages 1 and 2 vs. 3 and 4: 6/3 vs. 1/17, p=0.003), and the 5-year survival rate was better than in their nonthoracic counterparts (100% vs. 44.5%, p=0.015). The incidence of ganglioneuroblastoma was significantly higher in the thoracic group at the age of >1 year ( p=0.003). In six of nine patients from the thoracic group who were >1 year old, small areas of ganglioneuroma were identified in the tumor tissue. There was a stronger tendency for the maturation of neuroblastoma into ganglioneuroma in the thoracic group. Complete resection is not required for thoracic neuroblastoma regardless of the patient's age.

Four cases of acute infantile leukemia with translocation (4;11) (q21;q23) are reported. Although leukemia with this chromosomal abnormality has been classified as L2 acute lymphoblastic leukemia by the FAB classification, two of our cases appeared to be of myelomonocyte origin as demonstrated by cytochemical, immunologic, and electron microscopic studies and differentiation induction by 12- tetradecanoyl-phorbol-13-acetate and methylformamide. This chromosomal change is associated with poor prognosis.

Two permanent T-cell leukemia lines designated KH-1 and KH-2 were established from the peripheral blood of a 9-year-old boy with acute lymphoblastic leukemia and a 47-year-old man with adult T-cell leukemia (ATL). No T-cell growth factor was used. KH-1 cells grew as single cells and KH-2 cells formed clusters in suspension culture. Erosette formation, the absence of immunoglobulin determinants and Epstein-Barr-virus-associated nuclear antigen, and the presence of T-cell antigens revealed by monoclonal antibodies were characteristics of these cell lines as in other established T-cell leukemia lines. Chromosome analysis at the beginning revealed mosaic presence of cells with 46, XY, t(8q+; 15q-) and 46, XY which was later completely replaced by the latter karyotype in KH-1, and abnormal karyotype, 47, XY, +3, t (8q-; 10p+) was maintained throughout the period of in vitro passage in KH-2. The donor patient of KH-2 formerly lived in the south-western part of Japan where ATL is considered endemic and numerous type-C virus particles were detected electron microscopically, in KH-2 cell pellets.