Dic (17;20) (p11;q11) preceded MLL gene amplification in a patient with de novo mixed-lineage leukemia.

We report a case of acute mixed-lineage leukemia, as seen in a 65 year-old female with MLL gene amplification and biallelic loss of wild type p53 gene. The diagnosis was based on the findings that her bone marrow (BM) blasts expressed cytoplasmic CD3 (cyCD3), B-lineage antigens and myeloid antigens accompanied by clonal rearrangements of IgH gene. The BM blasts consisted of small-sized peroxidase-negative blasts (97%) and large-sized peroxidase-positive blasts (3%). The BM blasts showed a complex "karyotype," including dic(17;20) (p11;q11), -5 and add (11q23). Add (11q23) abnormality was found in sideline karyotypes as well as the stemline abnormality of dic(17;20) (p11;q11). For the p53 gene, which is located at 17p13, fluorescence in situ hybridization analysis showed the loss of one of two p53 alleles. Furthermore, polymerase chain reaction-single-strand conformation polymorphism and following nucleotide sequencing showed that the p53 gene was mutated at codon 215, leading to an amino acid substitution from Ser to Arg. For the MLL gene, southern blot analysis showed that the MLL gene locus was amplified but not rearranged at its breakpoint cluster region, which is usually rearranged in balanced translocations with many partner genes. These findings suggest that MLL gene amplification may in this case be based on the genetic instability caused by the preceding biallelic loss of the wild type p53 gene.

[Elevation of Epstein-Barr virus (EBV)-DNA in the peripheral blood of a patient with age-related EBV-associated B-cell lymphoproliferative disorder].

A 69-year-old man was admitted to our hospital with fever and right neck lymphadenopathy. A neck lymph node biopsy was performed. In the specimens, immunoblasts were present with an admixture of small T lymphocytes and macrophagocytes. Immunohistochemcal staining of immunoblasts was positive for CD20, CD30 and EBER. Epstein-Barr virus (EBV) serology showed elevated IgG antibody to VCA, and EBV DNA was detected in the peripheral blood. Since he showed latency II without immunodeficiency disease, we diagnosed age-related EBV-associated B-cell lymphoproliferative disorder (EBV-LPD) as a result of aging and EBV infection. He was treated with 6 courses of the CHOP regimen plus rituximab, and achieved complete remission. EBV-DNA became undetectable at remission. In age-related EBV-LPD, there is some possibility that EBV-DNA in the peripheral blood is valuable as a tumor biomarker.