A 60-year-old man presented to the emergency department with complaints of fatigue and weakness that began the previous week. He also stated that he had been experiencing shortness of breath without chest pain, cough, or dizziness. Upon physical examination, he had normal vital signs. However, his spleen was mildly enlarged.
Laboratory tests were ordered. The white blood cell (WBC) count and absolute lymphocyte counts were both elevated:
WBC = 28.5 x 109/L (reference range: 4 - 10 x 109/L)
Lymphocyte count = 20.0 x 109/L (reference range: 1.2 - 4.0 x 109/L)
A manual differential confirmed the elevated lymphocyte count. Smudge cells were also noted, as shown in the image.
To evaluate the patient's lymphocytosis, a blood sample was submitted for flow cytometry analysis.