Describe the general diagnostic approach.
Suspect acute leukemia in patients with suggestive clinical or laboratory features.
Confirm the diagnosis with a morphological assessment.
Further diagnostic studies: Immunophenotype, cytogenetics, and molecular genetic testing should be obtained in order to identify the subtype of acute leukemia.
In order to choose the best treatment strategy, the morphological assessment, immunophenotype, and genetic studies should be as comprehensive as possible.
What are findings of CPC and peripheral blood smear?
Complete blood count and peripheral blood smear
Leukocytes: The white blood cell count (WBC) may be elevated, normal, or low and is not a reliable diagnostic marker.
Platelets: typically mild to severe thrombocytopenia
Hemoglobin: typically anemia
Peripheral blood smear: presence of blasts (immature WBCs)
Describe findings of liver chemistries, renal function, coagulation studies and a comprehensive metabolic panel.
Liver chemistries and renal function tests: may be abnormal (e.g., secondary to disease infiltration)
Comprehensive metabolic panel and other metabolic studies
Often abnormal due to increased cell lysis (see also “Tumor lysis syndrome”)
Common findings include derangements of:
Sodium: hyponatremia OR hypernatremia
Potassium: hypokalemia OR hyperkalemia
Calcium: hypocalcemia OR hypercalcemia
Phosphate: hypophosphatemia OR hyperphosphatemia
↑ Uric acid
Coagulation studies: Mild coagulopathy may be present. Studies may also help to identify features of DIC.
What can be an emergency in leukemia?
The identification of DIC suggests APL, which is a medical emergency. Consult hematology and/or oncology immediately and transfer the patient to a critical care unit.
What is the confirmatory diagnostic test of choice?
Histopathological features should be assessed using bone marrow aspiration and biopsy. If unavailable, a peripheral blood smear may be sufficient.
When are specialized studies used?
These studies are used to further characterize the cell line involved; some characteristics may be associated with a better response to certain therapies. These studies should be ordered in consultation with a specialist.
Describe the screening for extramedullary disease.
Consider the following studies to detect extramedullary disease based on the subtype of acute leukemia and clinical evaluation of the patient:
CNS infiltration (common in ALL)
Perform a lumbar puncture and obtain CSF flow cytometry.
Consider brain and spine CT or MRI.
Testicular infiltration (relatively common in ALL): testicular ultrasound
Thymic infiltration (primarily in T-cell ALL): Chest x-ray or CT chest may show a mediastinal mass.
Hepatosplenic infiltration: Abdominal CT or ultrasound may show organ enlargement.
Other forms of extramedullary disease: Consider PET-CT and/or lymph node biopsy.