면역표현형 CD41a-/CD61-/CD42a+ 급성거대핵모세포성백혈병 다운증후군 환아 1예 = Acute Megakaryoblastic Leukemia with CD41a−/CD61−/CD42a+ Blasts in an Infant with Down Syndrome

다국어 초록 (Multilingual Abstract)

Infants with Down syndrome have increased incidences of transient abnormal myelopoiesis (TAM) and acute leukemia, which are usually associated with acute megakaryoblastic leukemia (AMKL). A 5-day-old girl with Down syndrome was diagnosed with TAM; 4 months later, acute leukemic transformation was suspected. Bone marrow (BM) examination was performed, and the infant was diagnosed with acute leukemia (80% blasts). Although BM aspirates showed the presence of megakaryocytic blasts with cytoplasmic blebs, flow cytometry analysis revealed that they were negative for cells with CD41a and CD61 immunophenotypes. Further analysis revealed that the megakaryocyte-related marker CD42a was positive in 57% of blasts. Morphologic and immunophenotypic features are required to establish the lineage of megakaryocytic blasts, which are necessary for diagnosing AMKL. As most cases of AMKL were positive for CD41 and/or CD61 markers, their presence was evaluated during routine analysis. In order to identify the immunophenotypic features of AMKL in an infant with Down syndrome, we performed additional flow cytometry for CD42a, one of the megakaryocytic markers, and were able to assist in the early diagnosis of AMKL, as well as to use CD42a as an effective follow-up marker.

국문 초록 (Abstract)

다운증후군소아들에게는 일시적 골수조혈이상 및 급성백혈병이 자주 나타나며, 급성백혈병 중 급성거대핵모세포성백혈병과의 연관성이 크다. 생후 5일 된 다운증후군 여자 환아가 일시적 골수조혈이상으로 진단을 받고, 4개월 후 급성백혈병으로의 이환이 의심되어 골수검사를 시행하였다. 세포흡인검사에서 골수모세포가 80%로 급성백혈병으로 확인되었으며 골수모세포에서 세포위족이 관찰되었지만, 유세포검사 결과에서 면역표현형 CD41a와 CD61은 음성소견을 보였다. 거대핵세포 계열을 확인하고자 CD42a 표지자에 대한 추가적인 유세포검사가 시행되었으며 골수모세포의 57%에서 CD42a 양성소견을 확인하였다. 급성거대핵모세포성백혈병의 진단을 위해서는 거대핵세포계열 골수모세포들에 대한 형태학적, 면역표현학적 특성이 고려되어야 한다. 대부분 급성거대핵모세포성백혈병 증례들에서 CD41 및/또는 CD61 표지자 양성소견이 나타나므로 일반적으로 이 두 가지 항원에 대한 유세포검사가 실시된다. 저자들은 다운증후군 환아에서 발생된 급성거대핵모세포성백혈병의 면역표현형의 확인을 위해 거대핵세포계열 표지자 중 하나인 CD42a를 추가적으로 유세포검사를 하여, 초기진단에 도움받았을 뿐 아니라, 항암치료 후 치료효과의 추적관찰 표지자로 활용했던 증례를 경험하였기에 보고한다.

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