I am sometimes referred patients with mild leukopenia whose white blood cell differential shows perfectly normal (albeit low-normal) subtype counts. In other words, low-normal counts for neutrophils, lymphocytes and/or monocytes (eosinophils and basophils don’t really count since they already occur in such low numbers) add up to a low total white blood cells count (leukopenia, defined as WBC count < 4.0 x109/L).
When this occurs as an incidental finding, there is generally no need for further work-up!!
