Pelger-Huët Anomaly

Pelger-Huët anomaly is an autosomal dominant benign condition found in 1 in 6000 individuals.

The characteristic leukocyte appearance was first reported in 1928 by Pelger, a Dutch hematologist, who described leukocytes with dumbbell-shaped bilobed nuclei, a reduced number of nuclear segments, and coarse clumping of the nuclear chromatin.

In 1931 Huet, a Dutch pediatrician, identified it as an inherited disorder.

Neutrophils contain not more than two lobes to the nuclei (spectacle-shaped nuclei) and “band forms” are frequent. In the inherited anomaly, affected neutrophils with bilobed nuclei make up 60-90% of the neutrophils seen.

Anomalies resembling Pelger-Huët anomaly that are acquired rather than familial have been described as pseudo Pelger-Huët anomaly. The morphologic characteristic seen in pseudo Pelger-Huët anomaly is similar to Pelger-Huët anomaly. The acquired pseudo Pelger-Huët anomaly has been associated with pathologic conditions including acute and chronic myeloid leukemias, myelodysplastic syndrome (MDS), severe infections and some other toxic conditions.

Pseudo Pelger-Huët anomaly and micromegakaryocytes are considered to be highly characteristic and highly pathognomonic of MDS.

Usually, the congenital form is not associated with thrombocytopenia and leukopenia, so if these features are present more detailed search for myelodysplasia is warranted, as pseudo-Pelger–Huët anomaly can be an early feature of myelodysplasia.

When Pelger-Huët cells are identified, initially attempt to determine if the patient has a benign inherited anomaly or an acquired morphologic feature (ie, pseudo–Pelger-Huët anomaly). In pseudo-Pelger-Huët anomaly, cells may appear morphologically similar to inherited Pelger-Huët anomaly, but absence of these findings in other family members, a low percentage of affected cells (usually 5-20%), and involvement of other cell lines (eg, anemia or thrombocytopenia) suggest an acquired anomaly.