History
Heterozygotes are healthy with no excessive predisposition to infection. In homozygous individuals, Pelger-Huët anomaly (PHA) may be associated with skeletal anomalies [16]
Physical
Unique physical findings are not observed in heterozygous individuals with PHA. The proportion of neutrophils with abnormal morphology is usually 50% or more. This distinguishes it from pseudo–Pelger-Huët anomaly, which may be seen in association with malignancies and other disease states, for which the proportion of abnormal appearing cells is usually around 5%.
Homozygous individuals are extremely rare and inconsistently have skeletal anomalies such as postaxial polydactyly, short metacarpals, short upper limbs, short stature, or hyperkyphosis. [4]
The practical importance of identifying PHA lies in distinguishing this defect from a bandemia with a left-shifted peripheral blood smear that can be observed in association with infection. In addition, acquired or pseudo–Pelger-Huët anomaly often develops in the course of acute or chronic myelogenous leukemia and in myelodysplastic syndromes.
In pseudo–Pelger-Huët anomaly, the percentage of abnormal neutrophils is usually less than 20% and often around 5%. Coarser clumping of nuclear matter may be seen. Pseudo–Pelger-Huët cells may be seen in large numbers following paclitaxel or docetaxel therapy, but this is usually transient and resolves after 10-14 days of chemotherapy administration. The morphologic changes have also been described in myxedema associated with panhypopituitarism, vitamin B-12 and folate deficiency, multiple myeloma, enteroviral infections, malaria, muscular dystrophy, leukemoid reactions secondary to metastases to the bone marrow, and drug sensitivity.
Because PHA is autosomal dominant, when PHA is encountered on a blood smear, family studies can often relieve anxiety about pseudo–Pelger-Huët anomaly and avoid unnecessary investigations.
Causes
Pelger-Huët anomaly is secondary to a mutation of the LBR gene on band 1q42. [17] It is inherited in a highly penetrant, dominant pattern.
Research indicates that of diseases associated with variants of the neuroblastoma-amplified sequence (NBAS) protein, SOPH (short stature, optic nerve atrophy, and Pelger-Huët anomaly) syndrome is related to variation in the C-terminal. [18]
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Neutrophils in this blood smear (original magnification X1500) have the 2 characteristics of the Pelger-Huët anomaly: the pince nezappearance of the bilobate nuclei and excessively coarse clumping of chromatin. Used with permission from Little, Brown.
