Case Study Four:
An 80-year-old man was seen in the emergency room after a sudden onset of chest pain accentuated on inspiration. His cough was productive of yellow sputum, and he was short of breath. His temperature was 101.2°F. A chest X-ray revealed right middle lobe pneumonia.
A complete blood count (CBC) was ordered. The results were as follows:
|WBC||33.0 x 109/L||4.0 - 11.0 x 109/L|
|RBC||4.5 x 1012/L||4.5 - 5.9 x 1012/L|
|Hemoglobin||15.2 g/dL||13.5 - 17.5 g/dL|
|Hematocrit||44%||41 - 53%|
|Platelet||200 x 109/L||150 - 450 x 109/L|
|Segmented neutrophil||65||40 - 80%|
|Band neutrophil||10||0 - 5%|
|Lymphocyte|| 5||25 - 35%|
|Eosinophil|| 3||0 - 5%|
|Basophil|| 2||0 - 2%|
|Monocyte||25||2 - 10%|
A peripheral smear was reviewed based on the elevated WBC and increased monocyte count. A representative field from the Wright-Giemsa stained smear (1000X magnification) is shown on the right. The cells indicated by the blue arrows are atypical monocytes. They have abundant cytoplasm that is more blue than the typical gray-blue cytoplasm of normal monoctes. A few scattered vacuoles are also present. The atypical monocytes, in company with toxic neutrophils (indicated by the red arrow), appeared to be a response to infection. The patient had a past history of tuberculosis, which may account for the monocytosis.