Case Presentation: A 77-year-old man with a history of coronary artery disease and prior coronary artery bypass surgery presented with a five-day history of fever and shortness of breath. On examination, he had a temperature of 101.8°F, heart rate of 131 bpm, respiratory rate of 44, and oxygen saturation of 96% on room air. Laboratory tests revealed a WBC of 11,000/μL, hemoglobin of 6 g/dL, platelets of 100,000/μL, venous pH of 7.15, pCO₂ of 25 mmHg, lactate of 14.6 mmol/L, bicarbonate of 9 mmol/L, creatinine of 1.80 mg/dL, an anion gap of 28, Pro-BNP of 8867 pg/mL, and troponin of 939 ng/L. EKG showed ST depressions in the lateral leads, and chest X-ray revealed right lung infiltrates with bilateral congestion. Broad-spectrum antibiotics were started. The patient was admitted to the CCU due to concern for acute decompensated heart failure in the setting of severe sepsis secondary to pneumonia. Upon admission, the patient’s differential on the CBC showed blasts, reaching up to 26%. An acute blast crisis was suspected. Hematology review of the peripheral smear revealed increasing blasts and promyelocytes with numerous Auer rods, raising suspicion for acute leukemia. Due to increased work of breathing and severe acidosis, the patient required intubation. All-trans retinoic acid (ATRA) was initiated due to concern for acute promyelocytic leukemia, but it was discontinued after flow cytometry and bone marrow biopsy confirmed AML. The patient was extubated after three days, with improvement in shock and resolution of infection. Subsequently, the patient was started on induction therapy for AML, with venetoclax (a BCL-2 inhibitor) and decitabine (a hypomethylating agent). The patient is now doing well and is being followed by the Hematology/Oncology clinic.
Discussion: This case underscores the diagnostic complexities and multidisciplinary challenges of atypical presentations of AML. The patient’s initial symptoms were common to many acute conditions, which made diagnosis elusive. Laboratory findings were initially interpreted in the context of his comorbidities, but the turning point came with the CBC differential, which revealed blasts. This finding, along with the presence of Auer rods on the peripheral smear, was critical in shifting the diagnostic focus to a hematologic malignancy. AML can have various types of clinical presentations. Apart from the blasts, AML can present with anemia and thrombocytopenia. Flow cytometry is the primary diagnostic tool to differentiate acute myeloid leukemia (AML) from blast crises of chronic myeloid leukemia (CML). This is important as the two require distinct treatment approaches. Rapid diagnosis is critical, especially in cases of acute promyelocytic leukemia (APML), a subtype of AML, to prevent life-threatening complications like disseminated intravascular coagulation.AML treatment is tailored to the individual, involving options such as targeted chemotherapy, autologous hematopoietic stem cell transplantation, or enrollment in clinical trials.
Conclusions: This case illustrates the importance of thorough laboratory evaluation, including peripheral smear review, in detecting hematologic malignancies. It also highlights the need for flexibility in therapeutic strategies based on evolving diagnostic information. By recognizing and addressing atypical presentations of AML, clinicians can improve diagnostic accuracy, treatment efficacy, patient prognosis, and quality of care.