LAUSR

Dear Editor, Acute promyelocytic leukemia (APL) is frequently associated with disseminated intravascular coagulation (DIC) and hemorrhage, which contributes to its high mortality rate [1]. Molecular confirmation for identifying a PML-RARA rearrangement has to be performed when APL is suspected. In rare cases, APL coexists with other hematologic malignancies, and in such cases, the concomitant malignant cells could be underestimated [2-4]. We report a case of APL coexisting with primary plasma cell leukemia (PCL) without any history of chemotherapy. The Institutional Review Board of Chonnam National University Hwasun Hospital (CNUHH), Hwasun, Korea (CNUHH-2021-119) approved this study and granted a waiver of informed consent because of its retrospective nature. A 61-year-old man presented with lower back pain, exertional dyspnea, and buccal-mucosal bleeding at the hemato-oncology department of CNUHH on October 2013. He had no history of disease or treatment. A complete blood count revealed white blood cell (WBC) counts of 39.4×10/L; Hb, 63 g/L; and platelet counts of 22×10/L. Blood chemistry results were as follows: lactate dehydrogenase, 811 IU/L (reference interval [RI], 218– 472); serum creatinine, 2.0 mg/dL (RI, 0.5–1.3); total calcium, 108 mg/L (RI, 84–102); albumin, 2.7 g/dL (RI, 3.1–5.2); total protein, 6.5 g/dL (RI, 5.8–8.1); and β2-microglobulin, 36,675 μg/L (RI, 970–2640). The patient’s prolonged and elevated coagulation profiles suggested DIC. Peripheral blood (PB) and bone marrow (BM) aspirates revealed an acute leukemic state with 80% abnormal hypogranular promyelocytes having kidney-shaped or bilobed nuclei (Fig. 1A, B). A few faggot cells were also observed. In the scattergram of initial flow-cytometric analysis (Cytomics FC-500 Flow Cytometer and Kaluza Analysis Software, Beckman Coulter, Miami, FL, USA), we observed a large population of immature cells and small populations of lymphocytes and granulocytes, as seen in other leukemias. The clonal cell population stained weakly positive for myeloperoxidase (MPO) and negative for CD13, CD33, CD117, CD34, and HLA-DR. Multiplex reverse transcription PCR (HemaVision kit; DNA Technology, Aarhus, Denmark) revealed the presence of a PML-RARA rearrangement, and a conventional cytogenetic analysis demonstrated 46,XY,t(15;17)(q22;q12)[12]/ 46,XY[8] (Fig. 1C). The patient was treated with idarubicin plus all-trans retinoic acid for 40 days, and both t(15;17) and the PMLRARA rearrangement were undetectable at follow-up. The WBC count remained high, and the abnormal cells persisted on the PB smears. We performed follow-up BM studies 40 days after diagnosis. Flow-cytometric analysis revealed a mono-