Polyploidy in myelodysplastic syndrome: a case report

Mutation in SF3B1 gene promotes formation of polyploid giant cells in Leukemia cells

Giant cells with polyploidy, termed polyploid giant cells, have been observed during normal growth, development, and pathologic states, such as solid cancer progression and resistance to therapy. Functional studies of polyploidal giant cancer cells (PGCC) provided evidence that they arise when normal diploid cells are stressed, show stem cell-like properties, and give rise to tumors. In the present study, we report in K562 leukemia cell line that introduction of the hotspot K700E mutation in the gene SF3B1 using CRISPR/Cas9 method results in an increased frequency of multinucleated polyploid giant cells resistant to chemotherapeutic agent and serum starvation stress. These giant cells with higher ploidy are distinct from multinucleated megakaryocytes, are proliferative, and are characterized by increased accumulation of mitochondria. PGCC have been previously documented in solid tumors. This is the first report describing PGCCs in a cell line derived from a liquid cancer where increased frequency of PGCCs is linked to a specific genetic event. Since SF3B1 mutations are predominantly seen in MDS and other hematologic malignancies, our current findings will have significant clinical implications.

A case of near-triploidy in myelodysplastic syndrome with del(5q) combined with del(1p) and del(13q)

Numerical and structural chromosomal abnormalities are common in hematological malignancies. Near-triploidy (58-80 chromosomes) is a numerical abnormality observed in 3% of adult cases of acute lymphoblastic leukemia. Near-triploidy is rare in myeloid lineage hematologic malignancies and compared to near-triploidy in lymphoid malignancies, near-triploidy in myeloid malignancies is associated with poor outcomes. Few studies on near-triploidy in myelodysplastic syndrome (MDS) have been reported, and the clinicopathologic significance of this condition is still unclear. Here, we report a novel case of MDS with near-triploidy and multiple structural chromosomal abnormalities: del(5q) combined with del(1p) and del(13q). These abnormalities were detected by cytogenetic analysis with array comparative genomic hybridization (CGH). Our results suggest that array CGH can be a useful tool for detecting chromosomal abnormalities in patients with MDS.

Acquired Robertsonian translocations are not rare events in acute leukemia and lymphoma

Robertsonian translocations are the most common constitutional structural abnormalities but are rarely reported as acquired aberrations in hematologic malignancies. The nonhomologous acrocentric rearrangements are designated as Robertsonian translocations, whereas the homologous acrocentric rearrangements are referred to as isochromosomes. Robertsonian rearrangements have the highest mutation rates of structural chromosome rearrangements based on surveys of newborns and spontaneous abortions. It would be expected that Robertsonian recombinations would be more common than suggested by the literature. A survey of the cytogenetics database from a single institution found 17 patients with acquired Robertsonian rearrangement and hematologic malignancies. This is combined with data from the literature for a total of 237 patients. All of the possible types of Robertsonian rearrangements have been reported in hematologic malignancies, with the i(13q), i(14q), and i(21q) accounting for nearly 60%. Complex karyotypic changes are seen in the majority of cases, corresponding with disease evolution. These karyotypes consistently show loss of chromosomes 5 and/or 7 in the myelocytic disorders, nonacrocentric isochromosomes, and centromeric breakage and reunion. However, nearly 25% of the acquired rearrangements were found as the sole abnormality or in addition to an established cytogenetic aberration. Most of these were the i(14q) with the myelodysplasia subtypes refractory anemia and chronic myelomonocytic leukemia.

Additional cytogenetic abnormalities in adults with Philadelphia chromosome-positive acute lymphoblastic leukaemia: a study of the Cancer and Leukaemia Group B

We analysed the nature and prognostic significance of secondary cytogenetic changes in 111 newly diagnosed adults with acute lymphoblastic leukaemia (ALL) and t(9;22)(q34;q11.2) or its variants. Secondary aberrations were seen in 75 (68%) patients. They included, in order of descending frequency: +der(22)t(9;22), +21, abnormalities of 9p, high hyperdiploidy (>50 chromosomes), +8, -7, +X and abnormalities resulting in loss of material from 8p, gain of 8q, gain of 1q and loss of 7p. Eighty patients (72%) had > or =1 normal metaphase in their karyotype. There were four balanced and 12 unbalanced translocations previously unreported in ALL with t(9;22). The t(2;7)(p11;p13) and der(18)t(8;18)(q11.2;p11.2) were seen in two cases each, and have never before been reported in haematological malignancy. All but four patients were treated on front-line Cancer and Leukaemia Group B clinical protocols. The presence of -7 as a sole secondary abnormality was associated with a lower complete remission (CR) rate (P = 0.004), while the presence of > or =3 aberrations was associated with a higher CR rate (P = 0.009) and +der(22)t(9;22) with a higher cumulative incidence of relapse (P = 0.02). It will be of interest to see if newly diagnosed t(9;22)-positive adult ALL patients with these and other secondary aberrations respond differently to treatment regimens that include imatinib mesylate.

Cytogenetic survey of 117 Tunisian patients with de novo myelodysplastic syndrome

Cytogenetic studies were performed on 117 Tunisian patients with de novo myelodysplastic syndromes (MDS). According to the French-American-British (FAB) criteria 40 patients presented with refractory anaemia (RA, 34%), eight with refractory anaemia with ringed sideroblasts (RARAS, 7%), 19 with refractory anaemia with excess of blasts (RAEB, 16%), 16 with refractory anaemia with excess of blasts in transformation (RAEB-t, 14%), 18 had chronic myelomonocytic leukaemia (CMML, 15%) and 16 unclassifiable MDS (14%). Seventy-five were men and forty-two were women. Five were children and 112 were adults with a median age of 58 years. Fifty-five per cent of the patients presented clonal chromosome abnormalities. Rates of abnormality varied from one FAB subtype to the other: 55% in RA, 75% in RARAS, 63% in RAEB, 75% in RAEB-t and 28% in CMML. The most frequent chromosome abnormalities were del(5q) (22 cases), monosomy 7 (12 cases), del(12p) (6 cases), and trisomy 8 (5 cases). Rare abnormalities were also found: ring of chromosome 12 and trisomy 15. Conventional cytogenetics remains the basic technique in identifying chromosomal abnormalities associated with MDS.

Complex karyotype and N-RAS point mutation in a case of acute megakaryoblastic leukemia (M7) following a myelodysplastic syndrome

The development of acute megakaryoblastic leukemia (ANLL-M7) following myelodysplastic syndrome (MDS) has been described only in a few reports, and the mutations necessary for this transformation are still unknown. In this study, we describe a case of ANLL-M7 with a previous history of MDS presenting a complex karyotype 46,XX, t(4;11)(q21;q23),del(5)(q13q33),t(12;13)(p13;q21) and N-RAS point mutation. During MDS, the patient showed a hypercellular myelogram with dysplasia of the three myeloid lineages and the clinical symptoms characteristic of the 5q- syndrome. During the follow-up, we observed the appearance of two additional subclones, one with an isochromosome 17q and another with polyploidy. The presence of an isochromosome 17q in one subclone and polyploidy in another is probably due to the genetic instability generated by the malignant transformation.

Hypotetraploidy in a patient with small cell carcinoma

While numerical and structural chromosomal abnormalities characterize many hematopoietic and nonhematopoietic malignancies, the occurrence of polyploidy is by and large rare. We report here an interesting patient with small cell carcinoma (SCC) and hypotetraploidy initially referred to us because of a question of acute nonlymphocytic leukemia, M3 subtype, with a question of a 15;17 translocation characteristic of acute promyelocytic leukemia. However, the patient did not have a 15;17 translocation and the final hematopathologic analysis of the bone marrow aspirates and immunohistochemistry studies subsequently revealed the patient to have SCC. Small cell carcinoma is a highly malignant and a very aggressive neoplasm. A review of the literature, using Medline, Cancerlit, and the Science Citation Index, revealed that in most, if not all, reports, the presence of polyploidy is noted as a rare entity. In leukemia, reports of polyploidy point to a distinct category of patients with a poor risk for which more intensive treatment is needed. Limited information is currently available to assess the risk of polyploidy in small cell carcinoma. Our case is important not only because of the relative rarity of polyploidy, but also because insights gained from the study of this and other similar patients may help shed additional light on the mechanism of carcinogenesis, which is not fully known to date. As polyploidization is a manifestation of genetic instability and as genetic instability has been implicated in the genesis and progression of many cancers, it is perhaps not too surprising that polyploidy in our case was associated with a poor disease outcome. The patient has since expired.