Original post by Brandon Fainstad, MD and Camille Puronen, MD.
Edits and graphics by Yilin Zhang, MD
- Recognize blasts on a peripheral blood smear
- Recognize common complications of acute myeloid leukemia, specifically leukostasis
- Manage a patient with leukostasis
70 year old man with history of asthma presents to primary care clinic with 2 weeks of progressive SOB not relieved with home albuterol. He had received a 5 day course of prednisone 20 mg and azithromycin with no noticeable improvement. He now returns a week later with a fever, increasing fatigue, persistent SOB and now a mild non-productive cough. He denies nasal congestion, sore throat, chest pain, palpitations, weight changes, orthopnea/PND, or skin changes. No sick contacts or recent travel. He uses albuteral as needed for his asthma and drinks a cup of colloidal silver every day to prevent the flu.
On exam, he is afebrile, HR 88bpm, BP 120/76 and SpO2 93 % on RA. He appears comfortable, normal heart heart with regular rhythm, no murmurs or elevated JVD. He has bibasilar crackles and a soft, non-tender abdomen. No visible rashes.
WBC 142k (ANC 0, 81% blasts), Hct 15%, Plt 30
Cr 1.1, K 3.5, Ca 8, Phos 2, Uric acid 7.9
Based on this patient’s CBC and blood smear what disease process do these blasts cells represent?
The most important first step is determining myeloid vs. lymphoid. The presence of Auer rods (which are pathognomonic of AML), as seen in the above smear (arrow), confirm these are myeloblasts. In the absence of Auer rods myeloid origin can be confirmed with cytochemical studies or flow cytometry.
What are the major acute complications of this diagnosis and how might you prevent some of these complications?
- Tumor lysis syndrome (TLS):
- Lab diagnosis: 2 or more of phos >5, K >6, Ca <7 and Uric acid >8 (remember 5, 6, 7, 8).
- Clinical diagnosis: AKI (Cr >1.5), cardiac arrhythmia or seizure.
- Prophylaxis: Aggressive hydration, allopurinol (stops uric acid production) or rasburicase (breaks down uric acid – use if high risk or established clinical TLS)
- Monitoring: Labs q6h, cardiac monitoring and ICU if there is established clinical TLS.
*Do not replete calcium unless having cardiac arrhythmias as this will increase calciumphosphate deposition in the kidneys
- Anemia: common presenting feature to AML. However, PRBC transfusions in the setting of hyperleukocytosis should be avoided unless absolutely necessary as this could further increase the viscosity.
- Bleeding: thrombocytopenia is common and the platelets my be dysfunctiona. Also, DIC a common complication in APL in setting of hyperleukocytosis. Monitored with q6-8h DIC labs (CBC, INR, fibrinogen) and managed with appropriate replacement
- Infection – prophylaxis:
- Bacterial: levofloxacin (UW specific)
- Viral: acyclovir
- Fungal: fluconazole
Based on his clinical presentation what are the potential explanations for his shortness of breath and the above CXR findings?
Suspect leukostasis (hyperleukocytosis with respiratory, cardiac or neurologic symptoms) in patients with myeloblasts >100K. Alternatively, it is rare with lympoblast counts <400K.
How would you manage this?
TAKE HOME POINTS:
- Auer rods are pathognomonic of AML and useful for making the immediate diagnosis without cytochemical studies or flow cytometry.
- Symptomatic hyperleukocytosis (leukostasis) requires immediate cytoreduction with induction chemotherapy. Leukophoresis is only indicated if induction therapy is going to be delayed.
- Avoid pRBC transfusion in setting of hyperleukocytosis, unless absolutely necessary.
- Howard SC, Jones DP, Pui CH. The Tumor Lysis Syndrome. N Engl J Med 2011; 364:1844.