Two cases of secondary acute myeloid leukemia accompanying adult T-cell leukemia/lymphoma.

We identified 2 cases of secondary acute myeloid leukemia (AML) following adult T-cell leukemia/lymphoma (ATL) in patients who had previously received chemotherapy. Both cases were thought to represent therapy-related AML because the patients had previously received combination chemotherapy including epipodophyllotoxin, anthracycline, and alkylating agents for the ATL. The cases were diagnosed as AML M4 with eosinophilia and AML M2, with the chromosomal abnormalities inv(16)(p13q22) and t(8;21)(q22;q22), respectively. In our hospital, only these 2 cases of secondary AML accompanying ATL were identified among 90 cases of acute- or lymphoma-type ATL diagnosed from October 1999 to July 2006. The frequency of coexisting AML and ATL is lower than that reported for acute leukemia coexisting with other lymphoid malignancies. The low frequency of secondary leukemia with ATL may be associated with the short survival times of ATL patients.

Arsenic trioxide induces apoptosis in HTLV-I infected T-cell lines and fresh adult T-cell leukemia cells through CD95 or tumor necrosis factor alpha receptor independent caspase activation.

Arsenic trioxide (As2O3) has been reported to induce apoptosis in human T-cell leukemia virus type-I (HTLV-I) infected T-cell lines and fresh adult T-cell leukemia (ATL) cells and to induce G1 phase accumulation in HTLV-I infected T-cell lines. The present study aimed to clarify the pathway of As2O3-induced apoptosis in HTLV-I infected T-cell lines, MT-1 and MT-2, and fresh ATL cells separated from peripheral blood of patients with acute or chronic type ATL. Cells were treated up to 72 h at clinically tolerable concentrations of As2O3 (1-2 micromol/l) shown to be safe in patients with acute promyelocytic leukemia (APL). Activation of caspases 3, 8, and 9, loss of mitochondrial transmembrane potential and cleavage of poly (adenosine diphosphate-ribose) polymerase (PARP) were observed during As2O3 treatment. Furthermore, prior exposure to a broad-spectrum caspase inhibitor blocked As2O3-induced apoptosis but not G1 phase accumulation. While pre-treatment with a CD95 receptor-blocking antibody (Ab) or a TNF-alpha neutralizing Ab did not show such inhibitions in these cells. In conclusion, As2O3 induces apoptosis in HTLV-I infected T-cell lines and fresh ATL cells through CD95 or TNF-alpha receptor independent caspase activation.

A novel c-kit positive biphenotypic acute leukemia cell line, TMBL-1, carrying a p53 point mutation.

We established and characterized a c-kit positive cell line from the bone marrow of a patient with biphenotypic acute leukemia (BAL). The cell line, designated TMBL-1, carried a His-175 mutant p53. The immunophenotype of the primary leukemia cells at diagnosis was cytoplasmic CD3+, CD7+, CD13+, CD33-, interleukin-7 (IL-7) receptor+ and c-kit -. However, leukemia cells in relapse and TMBL-1 cells were CD33+ and c-kit +. Immunophenotypically, TMBL-1 is a BAL cell line that coexpresses T-lymphoid and myeloid markers which fulfill the criteria of the European Group for the Immunological Characterization of Leukemia. Stem cell factor (SCF), a key regulator of hematopoiesis signaling through c-kit, enhanced the proliferation of TMBL-1 cells. Direct sequencing revealed the conversion at codon 175 of the p53 gene in the TMBL-1 cells. Primary leukemia cells in relapse also carried the same point mutation but not at diagnosis. Moreover, TMBL-1 cells are sensitive to paclitaxel, which could induce p53-independent apoptosis. The biphenotypic features and p53 mutation may be associated with progression to a more malignant type. This cell line may provide new information on the role of SCF in the overlapping area between early T-lymphoid/myeloid cells, and help in the design of new therapies targeted towards p53 mutations.

[Indolent primary gastric adult T-cell leukemia/lymphoma with recurrent lesions limited to the stomach and duodenum].

A 75-year-old man visited our hospital complaining of heartburn in November 1997. Gastroscopical examination revealed ulcerous protruding extended from the gastric antrum to body and a flat, elevated lesion in the greater curvature of the stomach. Biopsy specimens revealed a CD4-positive malignant lymphoma. The serum anti-human T-lymphotrophic virus type I (HTLV-I) antibody test was positive. He was diagnosed as having primary gastric adult T-cell leukemia/lymphoma (ATLL; acute type). Complete remission was achieved with chemotherapy. In December 1998, the patient experienced a relapse. The lesions were limited to the region between the upper gastric body and the fornix and disappeared with radiation therapy. A second relapse was detected in the gastric greater curvature and descending portion of the duodenum in May 1999 but spontaneously disappeared in 5 months. The third relapse in May 2000 was systemic. Monoclonal integration of the HTLV-I provirus was observed in DNA extracted from ascitic lymphocytes. Chemotherapy was resumed, but the response was poor. The patient subsequently died of respiratory failure as a result of pneumonia. Although gastrointestinal involvement is frequent in ATLL, this appears to be a rare case of an idolent clinical course with lesions limited to the stomach and duodenum for 30 months.

Uncommon cases of immature-type CD56+ natural killer (NK)-cell neoplasms, characterized by expression of myeloid antigen of blastic NK-cell lymphoma.

Immature-type CD56(+) natural killer (NK)-cell neoplasms are classified as either myeloid/NK-cell precursor acute leukemia or blastic NK-cell lymphoma. We identified two cases of immature-type CD56(+) NK-cell neoplasms that were not categorizable as either of these entities. The first case involved a 74-year-old woman presenting with skin eruptions and pancytopenia due to bone marrow necrosis. Skin biopsy specimen revealed CD4(+), CD7(-), CD34(-), CD43(+), CD56(+), CD68(+), muramidase (lysozyme)(+), and myeloperoxidase (MPO)(-), and immunophenotyping of peripheral blood showed CD4(+), CD7(-), CD13(+), CD33(+), CD34(-), CD43(+), CD56(+), cytoplasmic (cy)CD68(+), CD123(+), and HLA-DR(+). The second case involved a 62-year-old man who had bilateral optic nerve tumor and presented with malignant cells in peripheral blood. Cell surface markers of malignant cells showed CD4(+), CD7(-), CD13(+), CD33(+), CD34(-), CD43(+), CD56(+), cyCD68(+), and HLA-DR(+). The phenotypes of tumor cells in both cases were compatible with blastic NK-cell lymphoma, except for the expression of myeloid antigen. Clinical presentations of these cases showed characteristics of both blastic NK-cell lymphoma and myeloid/NK-cell precursor acute leukemia.