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Cancer Genet Cytogenet 121:96–98 (2000)

2000 Elsevier Science Inc. All rights reserved.655 Avenue of the Americas, New York, NY 10010

A Case of Near-Triploidy in ChronicMyelogenous Leukemia

Birgitte Roland and Walter B. Blahey

ABSTRACT:

A 61-year-old woman with chronic myelogenous leukemia (CML) in accelerated phasehad a near-triploid bone-marrow karyotype. This karyotype is an unusual finding in CML, as we review12 previously published similar cases. These patients do not differ clinically from other patients withCML in blast crisis. The cytogenetic features of near-diploid and near-triploid CML are similar, exceptthat relative loss of chromosomes is more common and that isochromosome 17q has not been reportedin near-triploid CML. © 2000 Elsevier Science Inc. All rights reserved.

CASE REPORT

A 58-year-old woman with a history of adenocarcinoma ofthe breast was diagnosed with chronic myelogenous leuke-mia in chronic phase. The bone-marrow karyotype at diag-nosis was 46,XX,t(9;22)(q34;q11.2)[12]/46,XX[2]. Threeyears later, the patient had decreasing platelet and redblood cell counts, and the bone marrow showed 30%blasts. A diagnosis of accelerated phase, approaching blasttransformation, was made. At this time, the bone marrowkaryotype was 65

z

69,XX,

2

X,

2

3,

2

4,

2

5,

1

6,

2

7,

1

8,

2

9,t(9;22)(q34;q11.2),

1

11,

2

12,

2

17,

1

18,

1

19,

1

20,

1

21,der(22)t(9;22),

1

der(22)t(9;22)[cp19]/46,XX,t(9;22)[16]. A repre-sentative karyotype is shown in Figure 1. The patient died1 month later.

DISCUSSION

Secondary chromosome changes are common in chronicmyelogenous leukemia (CML) at the time of blast transforma-tion, with the most common abnormalities being an isochro-mosome 17q and additional chromosomes 8, 19, and der(22). Therefore, hyperdiploidy is a common finding in CMLin transformation. Few patients with CML, however, havebeen reported with chromosome counts in the near-triploidrange. To our knowledge, only 12 patients with a near-triploid karyotype have been reported previously [1–11].

The clinical features of the 12 patients reported previ-ously, plus our patient, were reviewed. Of the 12 patientswhere the stage of disease was mentioned, 11 were in ac-celerated phase or blast transformation when the near-triploid karyotype was obtained. Of the 7 cases whereblast morphology was noted, 6 were myeloid and 1 waslymphoid. From the history that was provided, there didnot appear to be other common clinical features: there wasno association with age (17–74 years), sex (7 female, 6male), or length of the chronic phase (2–9 years).

A review of the cytogenetic features of the 13 patientsshowed common chromosome alterations. Variability ofthe karyotype was noted in 7 patients. The chromosomecounts in all 13 cases range from 58 to 71, and the copynumber for each chromosome ranges from 2 to 4. Figure 2illustrates the number of cases with gain or loss of eachchromosome. The chromosomes that are most frequentlyin excess, relative to a triploid karyotype, are der(22) andchromosomes 6, 8, and 19. These gains are similar to thosein hyperdiploid CML, except that gain of chromosome 6 isuncommon in hyperdiploid cases. Relative to a triploidkaryotype, the most common losses in the 13 cases are ofchromosomes 7, 9, 16, 17, and X. Of these losses, onlymonosomy 7 is relatively common in hyperdiploid CML.Structural abnormalities in addition to translocation(9;22) were observed in 9 of 13 cases. Surprisingly, al-though i(17q) is the most common structural abnormalityin hyperdiploid CML in transformation, this abnormalitywas not seen in the 13 near-triploid cases. As heretoforenoted, however, loss of the entire chromosome 17 was fre-quent.

In conclusion, there are some cytogenetic differencesbetween hyperdiploid and near-triploid CML, most nota-bly the absence of isochromosome 17q in the latter.

From the Departments of Pathology and Laboratory Medicine,Oncology, and Medicine, University of Calgary and Calgary Labo-ratory Services (B. R., W. B. B.), Calgary, Alberta, Canada.

Address reprint requests to: Dr. B. Roland, Department of His-topathology, Foothills Hospital, 1403-29 St. N.W., Calgary,Alberta, Canada T2N T29.

Received January 6, 2000; accepted January 21, 2000.

Triploid Chronic Myelogenous Leukemia

97

Figure 1 A representative karyotype of a near-triploid bone-marrow cell. Arrows indicate the derivative chro-mosome 9 and three derivative chromosomes 22.

Figure 2 The number of near-triploid cases of CML showing gains (gray) and losses (black) of each chromosomeand of the derivative chromosome 22 (Ph). Gains and losses are relative to a triploid karyotype.

98

B. Roland and W. B. Blahey

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