Myeloid malignancies mainly, acute lymphoblastic leukemia (ALL) and lymphomas.

Found in chronic and acute myeloid malignancies and mainly B-cell lymphoid malignancies.

Chronic myeloid malignancies in 12 (7M/5F aged 43 to 87 years, median 57 years): 1 chronic myeloproliferative disorder (MPD) (Hoo et al., 1987), 4 polycythemia vera (PV) (Chen et al., 1998; Najfeld et al., 2007) and 7 myelodysplastic syndrome (MDS) patients (Billstrom et al., 1988; Smadja et al., 1988; Iurlo et al., 1989; Wang et al., 1997; Lindvall et al., 2001; Stamatoullas et al., 2006; Najfeld et al., 2007). Among them, 3 patients developed MDS after chemotherapy for multiple myeloma (Smadja et al.,1988; Iurlo et al., 1989) or chronic lymphocytic leukemia (Wang et al., 1997).
Acute myeloid leukemia in 9 (4M/5F aged 13 to 79 years, median 67 years): 1 acute myeloblastic leukemia with maturation (AML-M2) (Poppe et al., 2004), 2 acute myelomonocytic leukemia (AML-M4) (Adriaansen et al., 1988; Poppe et al., 2004), 1 acute monoblastic leukemia without differentiation (AML-M5a) (Negrini et al., 1995), 1 acute megakaryoblastic leukemia (AML-M7) (Teyssier et al., 1987) and 4 acute myeloid leukemia, NOS (Pedersen et al., 1997; Van Limbergen et al., 2002; Shali et al., 2006; Moosavi et al., 2009). 1 of them developed acute myeloid leukemia 1 year after a myeloproliferative disorder was diagnosed (Negrini et al., 1995).
Acute lymphoblastic leukemia in 5 (4M/1F aged 10 and 14 years, 3 unknown); 3 patients were diagnosed with B-ALL (Heerema et al., 1992; Paulsson et al., 2015; Coyaud et al 2010) and 2 with T-ALL (Gladstone et al., 1998).
B-cell lymhoma in 13: diffuse large B-cell lymphoma (DLBCL) in 6 (3M/3F aged 18, 70, 73. 81 and 83 years, 2 unknown) (Mark et al., 1979; Mikraki et al., 1992; Ruminy et al., 2006; Chapiro et al., 2008; Bacher et al., 2011; Narayan et al., 2013), Hodgkin disease in 6 (3M/3F aged 12, 21, 25, 25 and 29 years, 1 unknown) (Tilly et al., 1991; Dohner et al., 1992; Schlegelberger et al., 1994; Cook et al., 2004) and a 62-years old male patient with extranodal marginal zone B-cell lymphoma (Van Roosbroeck et al., 2016).
T-cell lymhoma in 2: a 37- years old female diagnosed with angioimmunoblastic T-cell lymphoma (Lepretre et al., 2000) and a 78-years old female with adult T-cell lymphoma/leukemia ( (HTLV-1+) (Tanaka et al., 2001).

41 patients; 22 males and 19 females aged 10 to 87 years; median 67 years.

i(9)(p10) usually occurs within a complex karyotype, in itself with poor prognosis, therefore its appearance may be associated with advanced disease and unfavourable prognosis; the clinical significance of isolated i(9)(p10) in MPD is unclear.

As an isochromosome 9p can be misinterpreted as 9q deletion, a much more common finding in hematological malignancies, fluorescence in situ hybridization with locus specific probes of chromosome 9p/9q is a helpful method to confirm this less frequent abnormality.

Present as a supernumerary +i(9)(p10), in addition to two normal chromosomal 9 in 23 patients: 1 MPD (Hoo et al., 1987), 3 PV (Chen et al., 1998; Najfeld et al., 2007), 5 MDS (Billstrom et al., 1988; Smadja et al., 1988; Lindvall et al., 2001; Stamatoullas et al., 2006; Najfeld et al., 2007), 3 AML (Teyssier et al., 1987; Pedersen et al 1997; Van Limbergen et al., 2002), 1 ALL (Coyaud et al., 2010) and 10 B-cell lymphomas (Tilly et al., 1991; Dohner et al., 1992; Mikraki et al., 1992; Schlegelberger et al., 1994; Cook et al., 2004; Ruminy et al., 2006; Chapiro et al., 2008; Bacher et al., 2011; Narayan et al., 2013; Van Roosbroeck et al., 2016).

Found as the sole extra i(9)(p10) in 1 MPD (Hoo et al., 1987) and 3 PV patients (Chen et al., 1998; Najfeld et al., 2007), in association with i(9)(q10) in 1 PV (Najfeld et al., 2007) and 1 ALL (Heerema et al., 1992). Associated with chromosome 5/chromosome 7 anomalies or their combination in 5 MDS (Iurlo et al., 1989; Wang et al., 1997; Lindvall et al., 2001; Stamatoullas et al., 2006; Najfeld et al., 2007) and 6 AML (Teyssier et al., 1987; Pedersen et al., 1997; Van Limbergen et al., 2002; Poppe et al., 2004; Shali et al., 2006; Moosavi et al., 2009) and found with t(9;11)(p21;q23) in 2 AML patients (Cuneo et al., 1993; Negrini et al., 1995). Found with del(6q), del(7q) in 1, del(5q),del(6q) in 1 (Gladstone et al., 1998) and t(6;14)(p22;q32),+del(7q) in 1 ALL (Coyaud et al 2010). Part of complex karyotypes associated with 14q32 rearrangements in DLBCL and part of hypedriploid/near triploid complex karyotypes in Hodgkin disease patients.

Isochromosome i(9)(p10) represents a rare but recurrent chromosome abnormality in hematological malignancies, especially in chronic myeloid disorders, acute myeloid leukemia and B-cell lymphomas such as DLBCL and Hodgkin disease. The formation of i(9)(p10) induce a loss of the long arm of the chromosome 9 and duplication of its short arm, or less frequently it results only in an extra copy of 9p when 2 normal chromosomes 9 are present. In both cases, gain of chromosome material from 9p leading to extra copies of a gene or genes appears to be important in disease pathogenesis via gene dosage effect. Among them, the tyrosine kinase gene JAK2 on 9p24.1 might be a candidate gene as its numerical gain and structural rearrangements characterize both myeloid and B-lymphoid neoplasms. Gain and amplification of chromosomal sequences spanning JAK2 has been observed in both JAK2617V>F-positive and -negative patients with Philadelphia chromosome negative myeloproliferative disorders, with or without +9/+9p chromosomal abnormalities, indicating that amplification of a genes on 9p, and not deletion of genes from 9q, may play a role in the pathogenesis (Najfeld et al., 2007). JAK2 copy gain is also one of the most common genetic alterations in B-lymphoid neoplasms, especially Hodgkin lymphoma and primary mediastinal large B-cell lymphoma (Van Roosbroeck et al., 2016). Several of the imbalances described, including a recurrent 9p24.1 amplicon that includes JAK2 and immunoregulatory PD-1 ligand genes, leading to increased JAK2 protein expression activating the JAK2/STAT signaling pathway in a copy number-dependent manner.

T-ALL

NHL