e1a2 (minor, P190) BCR-ABL1 양성 만성 골수성 백혈병의 사례보고

Abstract

TO THE EDITOR: Minor BCR-ABL1-positive chronic myeloid leukemia (CML) is a very rare subtype of CML, with only 1–2% of patients with CML exhibiting this fusion gene as a sole rearrangement [1]. Amongst the several reported cases in literature, and to the best of our knowledge, only one case has been reported in Korea so far [2]. In this letter, we report a Korean patient diagnosed with minor BCR-ABL1-positive CML.

An 81-year-old male with a history of hypertension and dyslipidemia was referred to our hospital because of marked leukocytosis. The complete blood count (CBC) at referral indicated anemia, leukocytosis, and thrombocytopenia, with a hemoglobin (Hb) level of 7.5 g/dL, white blood cell (WBC) count of 37.59×109/L, and a platelet count of 89×109/L. The differential counts of WBC were myelocytes 1%, metamyelocytes 2%, band neutrophils 13%, neutrophils 45%, eosinophils 2%, basophils 6%, lymphocytes 12%, and monocytes 19% (Fig. 1). Bone marrow (BM) biopsy and related cytogenetic studies were performed; bone marrow biopsy showed hypercellularity, with an estimated cellularity of 70–90% (Fig. 2) with granulocytic proliferation. Additionally, the number of megakaryocytes and dwarf megakaryocytes had increased (Fig. 3). Approximately 5.3% of all nucleated cells (ANCs) were counted as blasts, whereas the population co-expressing CD34(+), CD117(+), and myeloperoxidase corresponding to myeloblasts, was 2.28% of the total cells observed using flow cytometry (FCM). Pseudo-Gaucher cells were not observed. Monocytes accounted for 17.1% of the ANCs, consistent with the FCM results of 17.4%. Conventional chromosome analysis using BM cells exhibited 46,XY,t(9;22)(q34;q11.2)[20] (Fig. 4). Reverse transcriptase-polymerase chain reaction (RT-PCR) showed a minor (P190) BCR-ABL1 transcript of the e1a2 type (Fig. 5). No major (P210) or micro (P230) BCR-ABL1 transcripts were detected. Therefore, the patient was diagnosed with minor BCR-ABL1-positive CML in chronic phase.