Morphologic, immunologic and cytogenetic studies in acute myeloid leukemia following occupational exposure to pesticides and organic solvents.

In order to analyze the correlation between environmental exposure and the clinicopathological picture in acute myeloid leukemia (AML), cytogenetic, cyto-immunologic and clinical studies were performed in 70 newly diagnosed AML patients, 30 of which were anamnestically exposed to pesticides (21 cases) or to organic solvents (9 cases). Clonal chromosome aberrations, with involvement of chromosome 5 and/or 7 were more frequently encountered among exposed patients. While the classical t(15;17), t(8;21) and t(9;11) were detected more frequently among non-exposed patients, other recurring chromosome changes in the exposed group were: rearrangements leading to total or partial monosomy 17p (5 cases), structural aberrations involving the band 16q22 (4 cases), trisomy 11q (2 cases), breaks involving bands 6p23, 7p14, 11q13 (2 cases each). Cytologically, trilineage myelodysplasia was observed in 21 exposed patients, whereas morphologic aberrations of the non-blast cell population were confined to a minority of cells in most patients non-exposed. Immunologic studies revealed positivity for the CD34 stem cell marker in 80% exposed patients vs 22% in the non-exposed group. Conventional chemotherapy achieved complete remission in 3/21 patients exposed and in 16/32 patients non-exposed. Median survival was 2 months in the former group and 9 months in the latter group. These findings show that AML following occupational exposure to pesticides and organic solvents may represent a distinct cytogenetic and clinicopathological entity.

Chromosome aberrations in CD34-positive acute myeloid leukemia. Correlation with clinicopathologic features.

Morphologic, immunologic, and cytogenetic features were studied in 30 newly diagnosed patients with CD34-positive (CD34+) de novo acute myeloid leukemia (AML) in comparison with 30 patients with CD34-negative (CD34-) AML. Karyotype at diagnosis was abnormal in 25/30 CD34+ AML patients, of which nine had major karyotype aberrations (MAKA). Clonal chromosome changes were detected in 9/30 patients with CD34- AML. The most frequent chromosome aberration in CD34+ patients was -5/5q-, an aberration showing a strong association with the M2 FAB subtype of AML. Other recurring chromosome changes involved chromosome 16q (four cases) and chromosome 17p (three cases). Total or partial monosomy 7q was detected in three cases. Among CD34- AML, two patients had the classical t(15;17) and two had structural aberrations of 6q. Among patients with CD34+ AML, nine had MAKA in association with trilineage myelodysplasia (TMDS). TMDS was infrequent in CD34+ AML without MAKA and in CD34- AML. Complete remission (CR) was achieved in 8/30 CD34+ AML (26%), as compared with 22/30 CD34- AML (73%), and median survival was 2 months in the former group and 8 months in the latter. No patient with CD34+ AML and MAKA achieved CR, whereas 8/21 CD34+ AML without complex chromosome changes or with normal karyotype achieved CR. In conclusion, a distinct cytogenetic profile may be associated with CD34+ AML. Cytogenetic findings in CD34+ AML may be clinically relevant in that they may disclose a subset of patients with MAKA with a low CR rate.

Involvement of erythrocytic and granulomonocytic lineages by trisomy 11 in two cases of acute myelomonocytic leukemia with trilineage myelodysplasia. An interphase cytogenetic study.

To study the cytologic profile and lineage involvement in acute myeloid leukemia (AML) with trisomy 11, cytologic, cytogenetic, and interphase cytogenetic studies were performed at presentation in two cases of acute myelomonocytic leukemia (AML-M4). Patient 1 had +11 as the sole chromosome aberration in 16/20 karyotypes whereas two related clones with +11 in all abnormal metaphases (14/18) were detected in patient 2. A proportion of interphase cells with three signals, comparable to the proportion of abnormal metaphases, was detected by fluorescent in situ hybridization (FISH) in these patients. Morphologic aberrations of the nonblast cell population affecting multiple cell lineages, along with a circulating minor megakaryoblastic component, were observed at diagnosis in both patients. By separation of bone marrow cells over a density gradient of Percoll two cell fractions were obtained, the former containing more than 80% erythroid precursors (collected at a density of 1065-1075 mg/ml), the latter containing more than 78% blast cells plus granulomonocytic precursors (collected at a density of 1060-1055 mg/ml). FISH documented the presence of a majority of interphase nuclei with three signals in the erythroblast-enriched cell fraction and in the blast-enriched cell fraction. It is concluded that cytologic features, as well as interphase cytogenetic findings on enriched cell fractions, suggest the occurrence of multipotent stem cell involvement in AML-M4 with +11.

Heterogeneity of lineage involvement by trisomy 8 in myelodysplastic syndrome. A multiparameter analysis combining conventional cytogenetics, DNA in situ hybridization, and bone marrow culture studies.

To better understand the role of trisomy 8 in myelodysplastic syndrome (MDS), we performed a multiparameter analysis combining conventional chromosome studies (CCS), fluorescence in situ hybridization (FISH), and bone marrow (BM) culture studies in two patients with MDS evolving into acute myeloid leukemia (AML). A mosaicism of a cytogenetically normal clone and a clone with trisomy 8 was detected in both patients throughout the course of the disease, a finding confirmed by FISH on BM cells. The relative size of the trisomic clone increased from 52% to 71% (p < 0.0001) and from 53% to 69% (p = 0.001) of all BM cells at the time of the leukemic switch in patients 1 and 2, respectively. Combined FISH and immunophenotyping of BM cells showed involvement of the granulomonocytic lineage in patient 1 and involvement of erythroid cells as well as of the granulomonocytic lineage in patient 2. Only disomic lymphocytes were detected in both patients. FISH on single hemopoietic colonies grown in semisolid media detected trisomic CFU-GM and disomic BFU-E in patient 1, whereas a proportion of CFU-GM and BFU-E deriving from the trisomic clone was detected in patient 2. However, the percent of trisomic colonies was lower than the percent of involved granulomonocyte precursors and involved erythroblasts, as detected by combined FISH and immunophenotyping on fresh BM samples. We have thus shown heterogeneity of lineage involvement by trisomy 8 in MDS undergoing transformation into AML. Although preferential growth of disomic clones may occur in vitro, the finding of an increased size of the trisomic clone at the time of leukemic switch suggests that these cells had proliferative advantage in vivo over cells without trisomy 8.

[Immunophenotypic study of acute myeloid leukemia (AML): biological significance and prognostic implications]. / Studio immunofenotipico nelle leucemie acute mieloidi (LMA): significato biologico ed implicazioni prognostiche.

The immunophenotype of 61 de novo AML referring to the Institute of Hematology of Ferrara between January 1988 and September 1992 was studied in order to evaluate the prognostic impact and the biological implications of this approach. In this study we confirm the possible aberrant expression of some antigens and the lack of a strict correlation between FAB classification and immunophenotype. The expression of the CD14 and CD34 was correlated with a worse prognosis, while the CD34+ patients further showed a lower probability to achieve a complete remission.

Distinct cytogenetic and clinicopathologic features in acute myeloid leukemia after occupational exposure to pesticides and organic solvents.

BACKGROUND: To study the correlation of environmental exposure to potentially mutagenic agents and the clinicopathologic picture in acute myeloid leukemia (AML), clinical features, morphologic characteristics, immunophenotype, and cytogenetics were studied in 59 patients with newly diagnosed AML. METHODS: Based on interviews on occupational hazards and hobbies showing prolonged contact with pesticides (18 patients) and organic solvents (7 patients), 25 patients were categorized as "exposed". Thirty-four patients were categorized as "unexposed,", based on anamnestic findings. RESULTS: Light microscopic studies showed myelodysplasia involving multiple cell lineages in all assessable patients with professional exposure to pesticides and organic solvents, whereas morphologic aberrations of the non-blast cell population were confined to a minority of cells in unexposed patients. These findings were confirmed by electron microscopic studies in 31 patients. Immunologic analysis showed the presence of a minor megakaryoblastic component in six exposed patients and showed positive findings for the CD34 stem cell marker in 85% of exposed patients, a figure significantly higher as compared with that for unexposed subjects. Cytogenetic studies confirmed the frequent occurrence of 5q and/or 7q aberrations in patients occupationally exposed (10 of 25 cases). Other recurring chromosome aberrations in the exposed group were 17p-, trisomy 11q, and translocation of 16q, 6p, 7p, and 11p, whereas the classic AML-specific translocations (i.e., t[15;17]; t[8;21]) were detected only in unexposed subjects. Conventional chemotherapy achieved complete remission in 1 of 19 exposed patients, as opposed to 14 of 29 unexposed patients, with a median survival of 2 months in the former group and 8 months in the latter. CONCLUSIONS: Taken together, these findings document that AML in patients professionally exposed to toxic substances may represent a distinct cytogenetic and clinicopathologic entity. The clinicobiologic characteristics in these exposed patients are similar to the features of AML arising in patients with prior chemotherapy for another tumor, thus suggesting that similar transformation pathways may underlie leukemogenesis induced by cytotoxic drugs and by environmental exposure to some pesticides or organic solvents.

Lineage switch and multilineage involvement in two cases of pH chromosome-positive acute leukemia: evidence for a stem cell disease.

Philadelphia chromosome-positive acute leukemias (Ph+ AL) show variable cytologic features, possibly reflecting heterogeneous stem cell involvement. Morphologic, immunologic and cytogenetic studies were performed in two cases of Ph+ acute lymphoblastic leukemia (ALL) in order to better delineate the clinicobiological features of this cytogenetic subset of AL. Sequential cytoimmunologic studies in patient 1 documented a lineage switch from pro-B ALL with a minor myeloid component at diagnosis to minimally differentiated acute myeloid leukemia (AML) at relapse. In this patient the major breakpoint cluster region (M-bcr) was in a rearranged configuration and all metaphase cells showed t(9;22)(q34;q11), both at diagnosis and at relapse. In patient 2 a diagnosis of Ph+ early T-cell ALL with minor myeloid component was made. In this patient the M-bcr was in a germline configuration. Cytogenetic studies documented the presence of the Ph chromosome in all metaphases from a lymphoid cell population obtained by fine-needle aspiration of an enlarged lymph node, and from a bone marrow cell fraction enriched in granulocyte precursors. This finding suggests multilineage involvement in this patient. Lineage switch and multilineage involvement in two patients suggest that a pluripotent stem cell may be affected rather frequently in patients with Ph+ AL. These findings show that biologically Ph+ AL may resemble chronic myelogenous leukemia blast crisis, since it may originate from an undifferentiated stem cell carrying the t(9;22) translocation.