Pelger-Huet anomaly is the inherited form of neutrophilic hyposegmentation. Its transmittance is autosomal dominant, and the anomaly is present in about one out of every 6000 people. It is due to a mutation in the lamin β-receptor gene.
More than 70% of the segmented neutrophils will have bi-lobed or mono-lobed nuclei when present on a peripheral blood smear. A bi-lobed nucleus will have two round segments of nearly equal size, connected by a thin chromatin strand. A mono-lobed nucleus may be peanut-shaped, slightly indented, or round; chromatin appears fully mature, and parachromatin is evident. Pelger-Huet anomaly in the homozygous state has an increased number of cells with singular round nuclei and decreased numbers of the bi-lobed forms.
The primary function of neutrophils is phagocytosis. Neutrophilic function (phagocytosis) is unaffected by either the acquired or the inherited anomaly. Since inherited Pelger Huet anomaly is associated with functionally normal neutrophils, neutrophils are considered a nonpathological variant.
The image to the right shows a peripheral blood smear from a Pelger-Huet patient. Note the hypopigmentation of the neutrophils.
