Acute Promyelocytic Leukemia: Life-threatening Emergency with a Favorable Prognosis – Analysis of Two Classic and Two Variant Cases with Literature Review

Abstract: Acute promyelocytic leukemia (APL) is a distinct subtype of acute myeloid leukemia (M3) characterized by a block in myeloid differentiation at the promyelocyte stage, with a typical association to the t(15;17)(q22;q12) translocation and PML-RARα fusion gene. Although once considered highly fatal due to hemorrhagic complications, APL is now one of the most treatable forms of leukemia, owing to targeted therapies such as all-trans-retinoic acid (ATRA) and arsenic trioxide. We report four cases of APL, including two classic hypergranular forms and two hypogranular variants. The cases illustrate the heterogeneity of clinical presentations, ranging from anemia and hemorrhagic syndromes to incidental findings, with complications including differentiation syndrome, renal failure, and disseminated intravascular coagulation (DIC). Diagnosis was established through cytology, cytochemistry, immunophenotyping, and cytogenetic analysis, which confirmed t(15;17) in all cases. Treatment with ATRA, alone or in combination with chemotherapy, led to favorable clinical and biological outcomes in three patients, while one patient died from DIC in the absence of timely ATRA initiation. This case series emphasizes the critical importance of early recognition and cytological confirmation of APL, allowing for rapid initiation of targeted therapy to prevent early mortality.