ALL-1 gene rearrangements in DNA topoisomerase II inhibitor-related leukemia in children

We examined clinical, morphologic, and cytogenetic features and ALL-1 (MLL, Htrxl, HRX) gene rearrangements in 17 cases of secondary leukemia that occurred 11 months to 9 years from diagnoses of primary cancers in children who received topoisomerase II inhibitors or developed secondary leukemias typical of those associated with this therapy. Primary diagnoses included nine solid tumors and eight leukemias. Ten secondary leukemias were acute myeloid leukemia (AML), one was of mixed lineage, two were acute lymphoblastic leukemia (ALL), and four presented as myelodysplasia. Of 15 cases with 11q23 involvement, 11 (73%) were cytogenetically identifiable; four cases had molecular rearrangement only. By Southern blot, rearrangements within the ALL-1 gene were similar to sporadic cases. The results of this analysis suggest the following: (1) In most pediatric cases of topoisomerase II inhibitor-associated leukemia, there is disruption of the breakpoint cluster region of the ALL-1 gene at chromosomal band 11q23. (2) Exposure histories vary in secondary 11q23 leukemia, as the only topoisomerase II inhibitor was dactinomycin in one case, and, in another case, no topoisomerase II inhibitor was administered. (3) There is clinical, morphologic, cytogenetic, and molecular heterogeneity in pediatric secondary 11q23 leukemia. (4) There are some survivors of pediatric secondary 11q23 leukemia, but the outcome is most often fatal.     

Acute myeloblastic leukemia with trilineage myelodysplasia and CD34+ blast cells with abnormal chromatin clumping

Abnormal chromatin clumping can be observed in myelodysplastic syndromes, myeloproliferative syndromes, acute leukemias and the abnormal chromatin clumping syndrome. It occurs mainly in mature and semimature blood cells. We report a case of acute myeloid leukemia with trilineage myelodysplasia (AML/TMDS) in which there was chromatin clumping in blast cells.     

Potential role for wild-type p53 in leukemias with MLL gene translocations

We used single-strand conformation polymorphism (SSCP) analysis of p53 exons 4-8 to screen for possible mutations in 25 pediatric de novo leukemias with translocations of the MLL gene at chromosome band 11q23. Of the 25 patients, 21 were infants. Fifteen cases were acute myeloid leukemia (AML), eight were acute lymphoblastic leukemia (ALL), and two cases were biphenotypic. Nineteen cases were studied at diagnosis and six at time of relapse. p53 mutations were absent in all 19 cases studied at the time of diagnosis. The only mutation was a TGC-->TTC transversion (cys-->phe) at codon 141 in exon 5 in a case of infant ALL at relapse that occurred by subclone evolution after MLL gene translocation. We previously showed that p53 mutations are also absent in pediatric treatment-related leukemias with MLL gene translocations. The absence of p53 mutations at initial transformation may suggest that the anti-apoptotic effect of mutant p53 is not important in leukemias with MLL gene translocations. Alternatively, exogenous DNA damage may be the common feature in treatment-related and de novo cases. Since MLL gene translocations may occur through DNA repair and wild-type p53 is central to DNA repair, the absence of p53 mutations raises the possibility that wild-type p53, not mutant p53, may be important in the genesis of leukemias with these translocations.     

A sole del(15q) anomaly in post-myelodysplasia acute myeloid leukemia

We report the second case of post-myelodysplasia acute myeloid leukemia (post-MDS AML) with a sole chromosome change del(15q). This anomaly is rarely seen. To our knowledge, only seven cases so far have been reported in human neoplasias, including one case each of acute myeloid leukemia (AML), acute lymphoid leukemia, post myelodysplasia AML, myelodysplastic syndrome, myelofibrosis, macroglobulinemia, Hodgkin's lymphoma and uterine leiomyoma. This case suggests that del(15q) is related to lympho-myeloproliferative disorders. Moreover, we speculate that certain oncogene(s) located on 15q might have some role in the progression of the disease, since the del(15q) anomaly appeared only in the AML phase in this case.     

Common region of ALL-1 gene disrupted in epipodophyllotoxin-related secondary acute myeloid leukemia

Translocations at chromosomal band 11q23 characterize most de novo acute lymphoblastic leukemias (ALL) of infants, acute myeloid leukemias (AML) of infants and young children, and secondary AMLs following epipodophyllotoxin exposure. The chromosomal breakpoints at 11q23 have been cloned from isolated cases of de novo ALL and AML. Using an 859-base pair BamHI fragment of human ALL-1 complementary DNA that recognizes the genomic breakpoint region for de novo ALL and AML, we investigated two cases of secondary AML that followed etoposide-treated primary B-lineage ALL. In the first case, the translocation occurred between chromosomes 9 and 11 and the breakpoint at 11q23 localized to the same 9-kilobase region of the ALL-1 gene that is disrupted in most of the de novo leukemias. In the second case the translocation was between chromosomes 11 and 19. The breakpoint occurred outside of the ALL-1 breakpoint cluster region.     

Who are the Irmas and what are the narratives?

One of the most serious possible consequences of cancer therapy is the development of a second cancer, especially leukemia. Several distinct subsets of therapy-related leukemia can be distinguished currently. These include classic therapy-related myeloid leukemia, leukemia that follows treatment with agents that inhibit topoisomerase II, acute lymphoblastic leukemia, and leukemias with 21q22 rearrangements or inv(16) or t(15;17). These types of leukemia are discussed in detail in this article.     

Paraffin section immunophenotyping of acute leukemias in bone marrow specimens

The immunohistochemical evaluation of acute leukemia specimens has been limited in the past due of the inability to detect many lineage-related antigens in paraffin sections. With the improvement in immunohistochemical methods as well as the introduction of new antibodies, these limitations are now reduced. To evaluate the diagnostic utility of paraffin section immunohistochemistry in the lineage determination of acute leukemias, 77 previously immunophenotyped acute leukemias were studied with a panel of antibodies that included antibodies directed against CD3, CD20, CD34, CD43, CD68, CD79a, HLA-DR, myeloperoxidase (MPX), and terminal deoxynucleotidyl transferase (TdT). The cases included 48 acute myeloid leukemias, 18 precursor B-cell acute lymphoblastic leukemias, 6 T-cell acute lymphoblastic leukemias, and 5 mixed precursor B/myeloid leukemias. This immunohistochemical panel correctly identified the lineage of 96% of both acute myeloid leukemias and acute lymphoblastic leukemias and identified evidence of mixed lineage in 60% of mixed lineage leukemias. Antibodies directed against CD3, CD79a, MPX, and TdT were found to be the most useful, although the latter three alone were not entirely lineage specific. These findings suggest a role for paraffin section immunohistochemistry in the lineage determination of some cases of acute leukemia.     

Rearrangements of the MLL gene in therapy-related acute myeloid leukemia in patients previously treated with agents targeting DNA-topoisomerase II

Chromosome band 11q23 is frequently involved in acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) de novo, as well as in myelodysplastic syndromes (MDS) and lymphoma. Five percent to 15% of patients treated with chemotherapy for a primary neoplasm develop therapy-related AML (t-AML) that may show rearrangements, usually translocations involving band 11q23 or, less often, 21q22. These leukemias develop after a relatively short latent period and often follow the use of drugs that inhibit the activity of DNA-topoisomerase II (topo II). We previously identified a gene, MLL (myeloid-lymphoid leukemia or mixed-lineage leukemia), at 11q23 that is involved in the de novo leukemias. We have studied 17 patients with t-MDS/t-AML, 12 of whom had cytogenetically detectable 11q23 rearrangements. Ten of the 12 t-AML patients had received topo II inhibitors and 9 of these, all with balanced translocations of 11q23, had MLL rearrangements on Southern blot analysis. None of the patients who had not received topo II inhibitors showed an MLL rearrangement. Of the 5 patients lacking 11q23 rearrangements, some of whom had monoblastic features, none had an MLL rearrangement, although 4 had received topo II inhibitors. Our study indicates that the MLL gene rearrangements are similar both in AML that develops de novo and in t-AML. The association of exposure to topo II-reactive chemotherapy with 11q23 rearrangements involving the MLL gene in t-AML suggests that topo II may play a role in the aberrant recombination events that occur in this region both in AML de novo and in t-AML.     

Fluorescence in situ hybridization analyses of hematologic malignancies reveal frequent cytogenetically unrecognized 12p rearrangements

Thirty-two hematologic malignancies--nine with cytogenetically identified 12p abnormalities and 23 with whole or partial losses of chromosome 12--were selected for fluorescence in situ hybridization (FISH) investigations of 12p. These analyses revealed structural 12p changes, such as translocations, deletions, insertions, inversions and amplification, in 20 cases. ETV6 rearrangements were detected in three acute leukemias. One acute undifferentiated leukemia had t(4;12)(q12;p13) as the sole anomaly. The second case, an acute myeloid leukemia (AML), displayed complex abnormalities involving, among others, chromosomes 9 and 12. The third case, also an AML, had an insertion of the distal part of ETV6 into chromosome arm 11q and into multiple ring chromosomes, which also contained chromosome 11 material, resulting in an amplification of a possible fusion gene. The fusion partners in these cases remain to be identified. Thirty-one additional breakpoints on 12p could be characterized in detail. The majority of these breaks were shown to result in interchromosomal rearrangements, possibly indicating the location of hitherto unrecognized genes of importance in the pathogenesis of hematologic malignancies. The FISH analyses disclosed terminal or interstitial 12p deletions in 18 cases. Seven myeloid malignancies showed deletions restricted to a region, including ETV6 and CDKN1B, which has been reported to be frequently lost in leukemias. In four cases, the deletions involved both these genes, whereas two AML displayed loss of CDKN1B but not ETV6, supporting previously reported findings indicating a region of deletion not including this gene. However, one myelodysplastic syndrome lacked one copy of ETV6 but not CDKN1B. Hence, we suggest a minimal region of deletion on 12p located between the ETV6 and CDKN1B genes.     

Time of host-seeking by Culex tarsalis (Diptera:Culicidae) in California

The translocation (6;9)(p23;q34) is a rare cytogenetic aberration found in patients with acute myeloid leukemia (AML). The clinical, morphologic, and immunophenotypic findings of eight t(6;9) acute leukemias are described. The patients included six men and two women with a mean age of 38.5 years. The leukemias were classified in the French-American-British (FAB) system as AML FAB M2 in four cases and as FAB M4 in four cases. Underlying myelodysplasia was evident in six cases. Bone marrow basophilia was found at presentation in six of the seven cases studied. In two cases with basophilia, darkly stained granules were also present in many eosinophils. In one case, initial basophilia was absent, but was present at relapse, as were eosinophils containing darkly stained granules. Iron stains were available in five cases; four showed increased incorporation and three had ringed sideroblasts. All cases studied by flow cytometry (six at presentation and three at relapse) expressed CD13, CD33, and human leukocyte antigen-DR. At presentation, five cases were CD34 negative. In one case at presentation, a subset of blasts (18%) weakly expressed CD34. Three cases studied at relapse were positive for CD34. Two of seven cases studied were terminal deoxynucleotidyl transferase positive. The t(6;9)(p23;q34) was the only cytogenetic abnormality in five cases. Trisomy 8 was found in two cases, and ring 12 was present in one case. Three patients are living with refractory leukemia 6 weeks to 6 months after initial diagnosis, and three patients died of complications of allogeneic bone marrow transplantation. Only one patient is alive without evidence of disease 3 years after bone marrow transplantation. t(6;9) leukemia is an unusual type of AML that is associated with poor prognosis, early age of onset, basophilia, myelodysplasia with frequent ringed sideroblasts, and a CD34-negative initial phenotype.     

Secondary acute myeloid leukemia following treatment with VP16-containing regimens for non-Hodgkin's lymphoma

We report on two patients who developed a secondary acute myeloid leukemia (sAL) after treatment for non-Hodgkin's lymphoma (NHL) with regimens containing low to intermediate doses of VP16. Clinical and hematologic features in these two patients were consistent with epipodophyllotoxin-associated sAL. In one case, a rearrangement of chromosome band 11q23 was detected.     

Thyroid hemiagenesis

The translocation t(12;22)(p13;q11) has been consistently described in myeloid malignancies and shown to result from a fusion between the TEL and MN1 genes. Previously described deletions of 12p in acute lymphoblastic leukemias have been recently shown to harbor undetected translocations involving the TEL gene at 12p13. We document a case of an aggressive chronic B-cell leukemia whose cells had trisomy 12 and two unbalanced translocations involving 12p13, including a t(12;22)(p13;q11) as shown by conventional cytogenetics and fluorescence in situ hybridization (FISH). The 12p13 breakpoint of the t(12;22)(p13;q11) was telomeric to the TEL gene, and the second unbalanced translocation with breakpoint 12p13 resulted in the deletion of TEL. This case demonstrates that TEL gene deletions may be relevant in cases of mature B-lymphoproliferative diseases.     

Radiological reasoning and its computer-based simulation. Reasons to use computer-based diagnostic systems developed on shells

p53 overexpression was studied immunohistochemically in paraffin-embedded bone marrow biopsies using a recently described technique for antigen retrieval based on microwave oven heating of paraffin sections. Using a monoclonal antibody (PAb1801) that reacts with human cellular p53, nuclear staining was detected in 7/11 (63%) therapy-related myelodysplastic syndromes and in 3/4 (75%) therapy-related acute myeloid leukemias. Conversely, staining for p53 was seen only in 9/40 (22%) cases of "primary" hematologic conditions (P < 0.007); these included myelodysplastic syndromes [#2], acute myeloid leukemia [#4], and chronic granulocytic leukemia in accelerated phase or blast crisis [#3]. Biopsies of normal controls and of chronic granulocytic leukemia in stable phase were consistently p53(-). Nine of the 10 karyotyped p53(+) acute myeloid leukemia/myelodysplastic syndrome cases showed complex cytogenetic findings with frequent involvement of chromosome 5 and/or 7. Only four of the 33 karyotyped p53(-) cases showed similar cytogenetic changes. Chromosome 17 involvement was present in four of 13 (31%) cytogenetically assessed p53+ cases, but in none of the p53(-). In univariate analysis, p53 expression in both MDS and AML was significantly associated with shorter survival. The frequent overexpression of p53 in therapy-related myelodysplastic syndromes, therapy-related acute myeloid leukemias and in accelerated phase/blast crisis, chronic granulocytic leukemia and its strong association with complex karyotypes suggests an important role of this gene in the pathogenesis of these leukemic conditions.     

Inhibitory effects of hydroxystilbenes on cyclooxygenase from sheep seminal vesicles

Therapy-related acute myeloid leukemias with balanced translocations affecting the 11q23 chromosome region are one of the most serious complications of treatments with topoisomerase II inhibitor drugs as epipodophillotoxins and anthracyclines. 1,2-5 These cases are usually associated with short interval time from previous chemotherapies, absence of myeloid dysplastic phase, hyperleukocytosis and young age. We and others have recently identified and cloned the ALL1 gene at 11q23 band (also named MLL, HRX. Hrxt) which is consistently altered in t-AML following therapies with topo II targeting drugs. However, there are few reports of cases of t-AML, clinically and biologically similar to the subtype of leukemias secondary to exposure to topo II inhibitors drugs but without the involvement of the ALL1 gene. These observations suggest that genes other than ALL1 which are etiopathogenetically relevant for hematological neoplasias are located in this cytogenetic region.     

The reliability and specificity of c-kit for the diagnosis of acute myeloid leukemias and undifferentiated leukemias. The European Group for the Immunological Classification of Leukemias (EGIL)

We document findings on c-kit (CD117) expression in 1,937 pediatric and adult de novo acute leukemia cases, diagnosed in five single European centers. All cases were well characterized as to the morphologic, cytochemical, and immunologic features, according to the European Group for the Immunological Classification of Leukemias (EGIL). The cases included 1,103 acute myeloid leukemia (AML), 819 acute lymphoblastic leukemia (ALL), 11 biphenotypic acute leukemia (BAL), and 4 undifferentiated (AUL). c-kit was expressed in 741 (67%) AML cases, regardless of the French-American-British (FAB) subtype, one third of BAL, all four AUL, but only in 34 (4%) of ALL cases. The minority of c-kit+ ALL cases were classified as: T-cell lineage (two thirds), mainly pro-T-ALL or T-I, and B lineage (one third); cells from 62% of these ALL cases coexpressed other myeloid markers (CD13, CD33, or both). There were no differences in the frequency of c-kit+ AML or ALL cases according to age being similar in the adult and pediatric groups. Our findings demonstrate that c-kit is a reliable and specific marker to detect leukemia cells committed to the myeloid lineage, and therefore should be included in a routine basis for the diagnosis of acute leukemias to demonstrate myeloid commitment of the blasts. c-kit expression should score higher, at least one point, in the system currently applied to the diagnosis of BAL, as its myeloid specificity is greater than CD13 and CD33. Findings in ALL and AUL suggest that c-kit identifies a subgroup of cases, which may correspond to leukemias either arising from early prothymocytes and/or early hematopoietic cells, both able to differentiate to the lymphoid and myeloid pathways.