A 72-year-old female is being evaluated for strep throat by her family physician. Her symptoms include fatigue and a scratchy throat. A routine CBC shows these findings.
- What is your initial diagnosis?
- What other investigations are required?
Click for answer:
Diagnosis: acute leukemia
CBC Clues:
(1) Blast cells (2) Bicytopenia
Q1. What is your initial diagnosis?
Acute leukemia or MDS variant with blasts
Q2. What other investigations are required?
Tumor lysis labs (see box).
Tumor Lysis Syndrome
↑ K+, PO4, Uric acid
↓ Ca+
You should never see immature blood cells in the peripheral blood in a healthy patient. The finding of blast cells usually suggests an acute leukemic process or an MDS variant with blasts. Given that the white count is significantly elevated (> 100) there is also concern for leukostasis. This is a result of large tumor cells increasing blood viscosity and slowing blood flow.
CBC Pearls
• Blasts = Bad! Warrants urgent hematology/hospital referral
• Acute leukemia is defined by > 20% blasts (either peripheral blood or bone marrow)
The result is end-organ damage that can be life-threatening, often involving the brain and lungs. Emergent medical assessment in a hospital setting is required to initiate work-up and early management. The bicytopenia in this context likely reflects marrow infiltration of leukemic cells, leading to reduced production.
Leukemic patients with hyperleukocytosis are also at high risk of tumor lysis syndrome due to the vast number of leukemic cells. Appropriate prophylaxis measures should be taken into account prior to treatment with regular monitoring of electrolytes. Common electrolyte derangements of tumor lysis syndrome are listed in the Box, including severe hyperkalemia and hypocalcemia. These can lead to renal failure and cardiac arrhythmias if not treated promptly.