National Journal of Health Sciences, 2020, 5, 83-85 83 Acute Promyelocytic Leukemia in Pediatric Population: A Rare Presentation Rabiah Asghar, Javera Tariq, Shahzad Ali Jiskani*, Sundas Ali, Aneela Zafar Department of Pathology, Pakistan Institute of Medical Sciences Islamabad, Pakistan. INTRODUCTION Acute promyelocytic leukemia (APL), comprises 5% to 8% of acute myeloid leukemia (AML) cases. In the United States, it accounts for 4% to 8% of AML in children.The peak age in pediatric population is 9 to12 years old children and predomi- nance of females is seen [1]. Risk of AML is increased by presence of certain predisposing factors such as genetic, environmental, and acquired causes [2]. White blood cell count (WBC) of about 20,000/ mm3 is associated with a better prognosis, and WBC count of 100,000/mm3 is related to adverse outcomes [3]. Acute myeloid leukemia is diagnosed by presence of certain features e.g. morphology, cytogenetics and immunophenotyp- ing. Unlike other forms of AML, APL can cause coagulopa- thy and death if delay in diagnosis occurs. As per French – American – British (FAB) classification of acute myeloid leukemia, APML is morphologically considered as AML – M3 and is characterized as neoplastic proliferation of promy- elocytes in bone marrow. Expression of abnormal promyelo- cytes in the bone marrow is seen due to balanced reciprocal translocation t(15;17) (q24.1;q21.2) [4]. Survival rate of acute promyelocytic leukemia (75-80%) in pediatric age group is relatively improved due to introduction of targeted therapy which includes all-trans retinoic acid (ATRA) and chemother- apy [5]. CASE REPORT A seven year old boy resident of Swabi presented in Pakistan Institute of Medical Sciences (children hospital) with complaints of fever off and on for past 06 months, bruises and swelling on left leg for 1 week, blood in vomitus for 1day.On physical examination, he was pale without any lymphadenop- athy or organomegaly. LABORATORY FINDINGS Hemoglobin was 4.2 g/dL (11.8-14.7 ), red blood cell count was 1.54 X 106/μL( 4.10-5.20),white blood cell count was 1.7X 103/μL (3.8-10.4), hematocrit was 13.9%(34-42%), mean corpuscular volume (MCV) was 90.3 fL( 77.8-91.1), mean corpuscular hemoglobin (MCH) was 27.3 pg (27-31), mean corpuscular hemoglobin concentration (MCHC) was 30.2 g/dL (32-36), red cell distribution width (RDW) was 15.1% (11.4-13.5%). Platelet count was 10 X 109 /L (187-400). Reticulocyte count was 1.5%(1-2 %). Peripheral film showed a dimorphic blood picture due to recent transfu- sion. Differential Leucocyte Count showed Neutrophils: 04%, Lymphocytes: 26%, Monocytes: 02%, Eosinophils: 03%, Myelocytes: 05%, Atypical mononuclear cells: 60% (abnor- mal promyelocytes and blasts with Auer rods, Faggots cells containing bundles of Auer Rods). Platelets were decreased on smear. Peripheral film findings are depicted in Fig. (1). Fig. (1). Peripheral Smear Showing Abnormal Promyelocytes with Auer Rods. *Address correspondence to this author at the Department of Pathology, Pakistan Institute of Medical Sciences Islamabad, Pakistan. E-mail: shahzadbaloach289@gmail.com © 2020 NIBD Publications www.njhsciences.com Case Report Abstract: Acute Promyelocytic Leukemia (APL) is a very uncommon type of acute myeloid leukemiacomprising less than 10% of pediatric population. Acute Promyelocytic leukemia is a neoplastic proliferation of abnormal promyelocytes in bone marrow, caused by cytogenetic abnormality t(15;17). Majority of patients (80%) have long term survival, and death occurs in approximately 10% of patients in early course of the disease; mainly because of hemorrhage. Hemorrhagic complications can be reduced by appropriate therapy if started timely, which ultimately reduces the risk of death.We report a case of 7 years old boy with complaints of fever off and on for past 06 months, bruises and swelling on left leg for 1 week, blood containing vomiting for 1day. He was diagnosed as APL on bone marrow biopsy. Keywords: Acute promyelocytic leukemia, Paediatric, Retinoic acid syndrome, All-Trans retinoic acid, FAB AML-M3, Sudan Black-B. doi.org/10.21089/njhs.52.0083