Medical Definition of Neutrophil. Neutrophil: A type of white blood cell, a granulocyte that is filled with microscopic granules, little sacs containing enzymes that digest microorganisms. Also known as polymorphonuclear leukocyte or poly.
Definition of Neutropenia. Neutropenia: Not enough neutrophils, neutrophils being a type of white blood cell (specifically a form of granulocyte) filled with neutrally-staining granules, tiny sacs of enzymes that help the cell to kill and digest microorganisms it has engulfed by phagocytosis.
Severe congenital neutropenia (Kostmann syndrome) is a rare disorder that occurs sporadically in the US and is characterized by an arrest in myeloid maturation at the promyelocyte stage in the bone marrow, resulting in an absolute neutrophil count of < 200/Î¼L.