Acute lower limb ischemia revealing hypo granular acute promyelocytic leukemia

Abstract

Introduction: Acute promyelocytic leukemia (AML-M3), classified as acute Myeloid leukemia with PML RARA according to the 5th edition of the World Health Organization classification of haematolymphoid tumors 2022 [1], is marked by abnormal promyelocyte proliferation and is known for high risks of bleeding and thromboembolic complications. We present a case where lower limb ischemia revealed this leukemia in a child. Case report: An 11-year-old with minor ankle trauma developed severe lower limb ischemia, leading to the discovery of subtotal femoral artery thrombosis. Blood tests revealed hyperleukocytosis, thrombocytopenia, and anemia with 88 % blasts, confirming acute myeloid leukemia (AML-M3). Karyotyping showed a t(15;17) translocation, and the child was started on emergency chemotherapy. Discussion: Acute promyelocytic leukemia (APL), classified as AML-M3 with PML-RARA, is characterized by abnormal promyelocytes and accounts for about 10 % of acute leukemias, mostly in middle-aged adults. It has two variants: common hypergranular and rare hypogranular forms. APL can present with bone marrow failure, anemia, bleeding, and occasionally thromboembolic events, as seen in this case. The ischemia mechanism is not fully understood but may involve vessel obstruction by blasts or hypercoagulability. Diagnosis relies on clinical, morphological, phenotypic, and cytogenetic evidence, with treatment involving all-trans retinoic acid (ATRA) and arsenic trioxide (ATO). Conclusion: Hypogranular acute promyelocytic leukemia (AML3v) is a rare form and is even rarer when it is discovered following an ischaemic event, which is what makes our case so special.