Neutropenia is an inherited or acquired condition manifested by low numbers of circulating white blood cells known as neutrophils. The absolute neutrophil count (ANC) may be estimated directly or as the product of the total white blood cell count and the fraction of polymorphonuclear cells and band forms in the blood count differential and is generally expressed as the number of cells per mm3. The common toxicity criteria established by the US National Cancer Institute grade neutropenia as grade 0 for ≥2,000/mm3; grade 1 for ≥1,500–<2,000/mm3; grade 2 for ≥1,000–<1,500/mm3; grade 3 for ≥500–<1,000/mm3; and grade 4 for <500/mm3. However, the term neutropenia clinically is generally reserved for ANC <1,500/mm3 (grades 2 or greater).
Normal hematopoiesis is characterized by the controlled proliferation and maturation of multiple cell lines critical to the development of the healthy individual....