A 67-year-old male presents to the ED with a sore throat and easy bruising. He has 2 peripheral IVs inserted with bleeding around the sites. He has no other past medical history or medication use.
- What is your differential diagnosis for pancytopenia?
- How do you rule out acute promyelocytic leukemia (APML)?
Click for answer:
Diagnosis: acute leukemia, confirmed acute promyelocytic leukemia subtype (APML)
CBC Clues:
(1) Blast cells > 20% of total WBC count
(2) Pancytopenia
Q1: What is your differential diagnosis for pancytopenia?
Primary causes include aplastic anemia, leukemia, MDS, myelofibrosis and PNH. Secondary causes include nutritional deficiency, infection, iatrogenic, infiltrative, and hypersplenism.
Q2: How do you rule out acute promyelocytic leukemia (APML)?
Peripheral blood smear, coagulation studies
Suspected APML Management
STAT labs: blood smear, INR/PTT, fibrinogen, hemolysis panel
Treatment: ATRA
APML is a subtype of acute myeloid leukemia that is highly treatable but lethal if underrecognized. The high mortality stems, in part, from the severe coagulopathy often associated with APML. This manifests as disseminated intravascular coagulation (DIC), hyperfibrinolysis, or both. Hemorrhage, including pulmonary and intracranial bleeding, is also common. Prompt recognition of APML can be life-saving – all patients with pancytopenia should have a peripheral blood smear and coagulation studies to rule out APML.
CBC Pearls
• Blasts = Bad! Emergent blood film is indicated to assess for peripheral blast
• Thrombocytopenia and DIC are commonly seen in APML patients
All-trans retinoic acid (ATRA) is a highly successful treatment for APML. It should be initiated as early as possible if there is high suspicion of APML, even before diagnosis is confirmed. Early ATRA initiation is associated with improved mortality and reduction in hemorrhagic death. ATRA is thus a required resource in all Emergency Departments across Ontario.
The differential diagnosis for pancytopenia can be divided into primary and secondary categories. Primary includes aplastic anemia, leukemia, myelodysplastic syndrome, myelofibrosis, and paroxysmal nocturnal hemoglobinuria. Secondary causes include B12/folate deficiency, infection (e.g. tuberculosis), iatrogenic (e.g. chemotherapy, radiation), infiltrative (metastases, amyloidosis), and hypersplenism.