LETTER TO THE EDITOR

Translocation t(3;3)(q21;q26) and Thrombocytosis

We report two patients with acute myelomonocyt ic leukemia (AML-FAB subtype M4) and a structural chromosomal rearrangement t(3;3)(q21;q26) showing markedly different platelet counts at the time of diagnosis.

The first patient was a 70-year-old man who presented with AML de novo and a low platelet count (47,000/mm3). His bone marrow showed 57% blasts and de- creased megakaryocytes. The karyotype was 46,XY,t(3;3)(q21;q26). Following re- covery from chemotheray his platelet count rose to 650,O00/mm 3, but this may have represented rebound following therapy-induced bone marrow aplasia. With subse- quent relapse of his leukemia his platelet count again fell to 51,000/mm 3.

The second patient was a 43-year-old man who presented with refractory anemia with excess blasts in transformation. His platelet count was 2,600,O00/mm 3 and the peripheral blood showed large platelet forms and megakaryocyte nuclei. His bone marrow showed 23% blast cells, marked increase in megakaryocytes, and signifi- cant dysplasia of all three cell lines. His disease eventually transformed into AML and this was accompanied by a decrease in his platelet count (730,000/mm3). His bone marrow karyotype was 46,XY,t(3;3)(q21;q26) at diagnosis and showed no clonal evolution with the development of frank leukemia.

Both of these patients demonstrated an identical chromosomal rearrangement involving the long arm of both chromosomes #3, but differed significantly in their platelet count at presentation. Although AML in patients with structural rearrange- ments of chromosome #3, involving 3q21 and 3q26, is frequently associated with much higher platelet counts than are usually seen in patients with AML in general, we suggest that the increasing age of the patient and a higher percentage of blast cell infiltration of the bone marrow at the time of diagnosis may serve to lower the initial platelet count [1-3].

RANDY D. GASCOYNE MICHAEL C. NOBLE DAGMAR K. KALOUSEK

Cytogenetics Laboratory Cancer Control Agency of British Columbia

600 West lOth Avenue Vancouver, B.C. V5Z 4E6

Canada

REFERENCES

1. Bitter MA, Neilly ME, LeBeau MM, Pearson MG and Rowley JD (1985): Rearrangements of chromosome 3 involving bands 3q21 and 3q26 are associated with normal or elevated platelet counts in acute nonlymphocytic leukemia. Blood 66:1362-1370.

2. Sweet DDL, Golomb HM, Rowley JD, Vardiman JM (1979): Acute myelogenous leukemia and thrombocythemia associated with an abnormality of chromosome no. 3. Cancer Genet Cytogenet 1:33-37.

3. Norrby A, Ridell B, Swolin B, Westin J (1982): Rearrangement of chromosome no. 3 in a case of preleukemia with thrombocytosis. Cancer Genet Cytogenet 5:257-263.

Received March 5, 1986; accepted March 24, 1986.

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© 1986 Elsevier Science Publishing Co., Inc. Cancer Genet Cytogenet 22:365 (1986)