Understanding and recognizing the Pelger-Huët anomaly

A Review of the Hematological Picture of Severe COVID-19 Infection

Numerous hematological abnormalities have been documented in COVID-19 patients. We conducted an analysis of 82 articles from PubMed, focusing on the hematological characteristics observed in survivors (S) and non-survivors (NS) with moderate and severe COVID-19 symptoms, respectively. Our review underlines neutrophilia, lymphopenia, and thrombocytopenia as hallmark features of the disease. In severe cases, blood cell microscopy revealed the following abnormalities: i) an increased number of neutrophils, often displaying granularity, toxic granulation, and vacuolization; ii) lymphocytes with a notably blue cytoplasm; iii) several monocytes that contain vacuoles; iv) platelet aggregation; and v) basophilic stippling in red blood cells. Furthermore, scattergram analysis of COVID-19 patients revealed two common features: i) an increased neutrophil population and ii) the presence of a distinctive "sandglass pattern". This review underscores the critical role of hematochemical and cytomorphological blood cell analysis in COVID-19 patients, aiding clinicians in better recognizing and understanding the indicators of disease severity.

Targeting SRSF2 mutations in leukemia with RKI-1447: A strategy to impair cellular division and nuclear structure

Spliceosome machinery mutations are common early mutations in myeloid malignancies; however, effective targeted therapies against them are still lacking. In the current study, we used an in vitro high-throughput drug screen among four different isogenic cell lines and identified RKI-1447, a Rho-associated protein kinase inhibitor, as selective cytotoxic effector of SRSF2 mutant cells. RKI-1447 targeted SRSF2 mutated primary human samples in xenografts models. RKI-1447 induced mitotic catastrophe and induced major reorganization of the microtubule system and severe nuclear deformation. Transmission electron microscopy and 3D light microscopy revealed that SRSF2 mutations induce deep nuclear indentation and segmentation that are apparently driven by microtubule-rich cytoplasmic intrusions, which are exacerbated by RKI-1447. The severe nuclear deformation in RKI-1447-treated SRSF2 mutant cells prevents cells from completing mitosis. These findings shed new light on the interplay between microtubules and the nucleus and offers new ways for targeting pre-leukemic SRSF2 mutant cells.

Young Woman with Unexplained Neutropenia and Neutrophils with Bilobed Nuclei: Marrow Findings

A 27-year-old female with a history of chronic sinusitis was referred for the evaluation of asymptomatic neutropenia. The differential demonstrated a mild neutropenia, which eventually resolved on subsequent evaluation. The liver and the spleen were not palpable. Peripheral flow cytometry was normal. Peripheral blood smear (PBS) demonstrated numerous Pelger-Huet anomalous neutrophils with characteristic "pince-nez" nuclei, without significant abnormalities in the other cell lines. Due to the benign clinical nature of hereditary PHA, a bone marrow biopsy is almost never required. However, our patient's persistent and worsening neutropenia was unusual for hereditary PHA, so a bone marrow biopsy was performed to rule out MDS and leukemia. Our patient's bone marrow smears showed dysplastic changes to other cell lines including the megakaryocytes and erythroid precursors. Due to our patient's young age and concern that she may have a more serious marrow disorder, genetic testing was pursued. Germline testing in the LBR gene revealed a heterozygous pathogenic mutation, namely, the PR57837.17 variant, confirming the diagnosis of hereditary disease. The bone marrow biopsy performed on our patient illustrates that the presence of dysplasia does not rule out hereditary PHA and further genetic testing should be done in the appropriate clinical scenario. This case was an atypical presentation of hereditary PHA with confounding morphological features that would typically classify the disease as an acquired or pseudo-PHA, hence acting as a Pseudo-Pseudo-Pelger-Huet Anomaly.

Septic shock caused by Capnocytophaga canimorsus in a patient with heterozygous Pelger-Huët anomaly

Capnocytophaga canimorsus is a Gram-negative bacillus of the commensal flora of dogs and cats that can cause infections in humans through bites, scratches or contact with oral secretions. It can be difficult to identify in clinical microbiology laboratories because of the need for specific culture media. We present the case of a patient with no relevant medical history who was admitted with septic shock, where blood smear examination was crucial for the etiologic diagnosis of Capnocytophaga canimorsus infection. The patient was also diagnosed Pelger-Huët anomaly, a condition causing a defect in neutrophil chemotaxis, which may have contributed to the severity of the infection.

Genetic architecture of band neutrophil fraction in Iceland

The characteristic lobulated nuclear morphology of granulocytes is partially determined by composition of nuclear envelope proteins. Abnormal nuclear morphology is primarily observed as an increased number of hypolobulated immature neutrophils, called band cells, during infection or in rare envelopathies like Pelger-Huët anomaly. To search for sequence variants affecting nuclear morphology of granulocytes, we performed a genome-wide association study using band neutrophil fraction from 88,101 Icelanders. We describe 13 sequence variants affecting band neutrophil fraction at nine loci. Five of the variants are at the Lamin B receptor (LBR) locus, encoding an inner nuclear membrane protein. Mutations in LBR are linked to Pelger-Huët anomaly. In addition, we identify cosegregation of a rare stop-gain sequence variant in LBR and Pelger Huët anomaly in an Icelandic eight generation pedigree, initially reported in 1963. Two of the other loci include genes which, like LBR, play a role in the nuclear membrane function and integrity. These GWAS results highlight the role proteins of the inner nuclear membrane have as important for neutrophil nuclear morphology.

Cytogenetic follow-up studies on humans with internal and external exposure to ionizing radiation

Cells exposed to ionizing radiation have a wide spectrum of DNA lesions that include DNA single-strand breaks, DNA double-strand breaks (DSBs), oxidative base damage and DNA-protein crosslinks. Among them, DSB is the most critical lesion, which when mis-repaired leads to unstable and stable chromosome aberrations. Currently, chromosome aberration analysis is the preferred method for biological monitoring of radiation-exposed humans. Stable chromosome aberrations, such as inversions and balanced translocations, persist in the peripheral blood lymphocytes of radiation-exposed humans for several years and, therefore, are potentially useful tools to prognosticate the health risks of radiation exposure, particularly in the hematopoietic system. In this review, we summarize the cytogenetic follow-up studies performed by REAC/TS (Radiation Emergency Assistance Center/Training site, Oak Ridge, USA) on humans exposed to internal and external radiation. In the light of our observations as well as the data existing in the literature, this review attempts to highlight the importance of follow-up studies for predicting the extent of genomic instability and its impact on delayed health risks in radiation-exposed victims.

Pseudo Pelger-Huët anomalies as potential biomarkers for acute exposure radiation dose in rhesus macaques (Macaca mulatta)

PURPOSE

The potential for malicious use of radiation, or radiation accidents could potentially lead to acute, high radiation doses to the public. Following acute accidental exposure to high doses of radiation, medical intervention is pivotal to the survivability of the patient, and the sooner the appropriate measures are taken the better the odds for survival. Early estimates of acute accidental radiation doses can be determined via biomarkers such as dicentric chromosome analysis or scenario reconstruction using computer software. However, both take valuable time and can be expensive. Increased frequencies of abnormal neutrophils in peripheral blood, referred to as pseudo Pelger-Huët anomalies (PPHAs), have been shown to be potential biomarkers of radiation exposure in several scenarios, including the 1958 Y-12 criticality accident and the radium dial painters. PPHAs are potentially a faster and cheaper quantitative biomarker for radiation exposure, and here they were evaluated in acutely exposed rhesus macaques.

METHODS AND MATERIALS

Peripheral blood smears from acutely exposed rhesus macaques were evaluated for the percentage of neutrophils that displayed the PPHA morphology using light microscopy. Irradiated animals received 0 to 8.5 Gy total body radiation using one of two strategies: (1) linear accelerator-produced 6 MV photons delivered at 80 cGy/minute; or (2) Cobalt 60-produced gamma irradiation delivered at 60 cGy/min. Zero dose animals were used to determine a baseline percentage of PPHAs, and blood smears taken periodically throughout the lifetime of exposed animals post-irradiation were used to determine the persistence and biokinetics of PPHAs.

RESULTS

The baseline prevalence of the PPHA in rhesus macaques was determined to be 0.58 ± 0.46%. The dose-response curve with doses ranging from 0 Gy to 8.5 Gy (LD90/30) displayed a strong positive correlation between PPHA percentage and acute radiation dose (R² of 0.88 p =  3.62 × 10^-22). Statistically significant differences were found when animals were separated into dose cohorts of 0, 4, 6.4-6.5, and 8-8.5 Gy. The biokinetics model utilized only 4 Gy exposures and blood smears taken periodically over 3.1 years post-irradiation. PPHA morphology increases quickly following irradiation and appears stable over 3.1 years post-irradiation.

CONCLUSION

PPHA morphology was confirmed to be present in rhesus macaques, a dose-response relationship was constructed, and it is stable over 3 years post-irradiation. This study demonstrates that PPHA analysis can be a fast and cheap method of biodosimetry. Future studies will work to determine the accuracy of dose determination and lower limits of detection.

Acquired Pelger-Huët anomaly in a patient treated with valganciclovir

A follow-up blood count was performed on a 74-year-old woman diagnosed with colitis due to cytomegalovirus and under treatment with valganciclovir. The automated complete blood count revealed an abnormal white blood cells (WBC) scattergram together with WBC alert flags. The peripheral blood smear showed neutrophils with markedly hyposegmented nuclei or bilobed nuclei and very condensed chromatin or clumping chromatin all consistent with Pelger-Huët anomaly (PHA). We checked previous blood counts, ruling out an inherited PHA. We assessed the haematological, infectious and iatrogenic aetiologies for an acquired PHA. Once the valganciclovir treatment was completed and the drug was withdrawn, without changing the rest of the treatment, the morphological abnormalities of neutrophils were completely resolved. We conclude therefore that the acquired PHA presented by our patient is probably related to valganciclovir treatment.

The Pseudo-Pelger huët Cell as a Retrospective Dosimeter: Analysis of a Radium Dial Painter Cohort

Recently, the pseudo-Pelger Huët anomaly in peripheral blood neutrophils has been described as a new radiation-induced, stable biomarker. In this study, pseudo-Pelger Huët anomaly was examined in peripheral blood slides from a cohort of 166 former radium dial painters and ancillary personnel in the radium dial industry, 35 of whom had a marrow dose of zero above background. Members of the radium dial painter cohort ingested Ra and Ra at an early age (average age 20.6 ± 5.4 y; range 13-40 y) during the years 1914-1955. Exposure duration ranged from 1-1,820 wk with marrow dose 1.5-6,750 mGy. Pseudo-Pelger Huët anomaly expressed as a percentage of total neutrophils in this cohort rises in a sigmoidal fashion over five decades of red marrow dose. Six subjects in this cohort eventually developed malignancies: five osteosarcomas and one mastoid cell neoplasm. The pseudo-Pelger Huët anomaly percentage in these cases of neoplasm increases with marrow dose and is best fit with a sigmoid function, suggestive of a threshold effect. No sarcomas are seen for a marrow dose under 2 Gy. These results indicate that pseudo-Pelger Huët anomaly in peripheral blood is a reasonable surrogate for the estimation of alpha dose to bone marrow in historic radiation cases. Hypotheses are discussed to explain late (months to years), early (hours to days), and intermediate (weeks to months) effects of ionizing radiation, respectively, on the expression of genes encoding inner nuclear membrane proteins and their receptors, on the structure and function of nuclear membrane proteins and lipids, and on cytokinesis through chromatin bridge formation.

A common pathomechanism in GMAP-210- and LBR-related diseases

Biallelic loss-of-function mutations in TRIP11, encoding the golgin GMAP-210, cause the lethal human chondrodysplasia achondrogenesis 1A (ACG1A). We now find that a homozygous splice-site mutation of the lamin B receptor (LBR) gene results in the same phenotype. Intrigued by the genetic heterogeneity, we compared GMAP-210- and LBR-deficient primary cells to unravel how particular mutations in LBR cause a phenocopy of ACG1A. We could exclude a regulatory interaction between LBR and GMAP-210 in patients' cells. However, we discovered a common disruption of Golgi apparatus architecture that was accompanied by decreased secretory trafficking in both cases. Deficiency of Golgi-dependent glycan processing indicated a similar downstream effect of the disease-causing mutations upon Golgi function. Unexpectedly, our results thus point to a common pathogenic mechanism in GMAP-210- and LBR-related diseases attributable to defective secretory trafficking at the Golgi apparatus.

Inter-observer variance and the need for standardization in the morphological classification of myelodysplastic syndrome

In this era of genome medicine, the sub-classification of myeloid neoplasms, including myelodysplastic syndrome (MDS), is now supported by genetic testing in selected cases. However, as the initial suspicion and primary diagnosis of the disease still largely relies on morphological features and numbers of hematopoietic cells, the establishment of a uniform diagnostic basis, especially for cell morphology, is essential. In this study, we collected nearly 100,000 hematopoietic cell images from 499 peripheral blood smear specimens from patients with MDS and used these to evaluate the standardization of morphological classification by medical technologists. The observers in this study ranged between two to eleven for each image, and the images were classified according to MDS criteria through a web-based system. We found considerable inter-observer variance in the assessment of dysplastic features. Observers did not recognize cytoplasmic hypo-granularity unless almost all granules in neutrophils were absent. Pseudo Pelger-Huët anomalies were also often overlooked, except for cells with a very typical "pince-nez" appearance. Taken together, this study suggests a requirement for further standardization in terms of morphological cell classification, and a need for the development of automatic cell classification-supporting devices for the accurate diagnosis of MDS.

Stodtmeister Cells (Polymorphs with Pelger-Huët Anomaly) Showing "Faggots" in Mixed Phenotypic Acute Leukemia (T/Myeloid)

"Faggot" cells, named for the resemblance of multiple Auer rods to a bundle of sticks, are often considered sine qua non for acute promyelocytic leukemia. However, blasts in other acute myeloid leukemias rarely also show faggot cells. This case demonstrates faggot cells in stodtmeister cells in mixed phenotypic acute leukemia. In addition to being uncommon, this case also highlights the importance of immunophenotyping and genetic analysis in avoiding misdiagnosis and inappropriate therapy.

The Pseudo-Pelger HuËt Cell-A New Permanent Radiation Biomarker

Using archival peripheral blood slides obtained from patients in the 1958 Y-12 criticality accident, the authors have recently described the pseudo-Pelger Huët anomaly (PHA) in neutrophils as a new radiation-induced biomarker. The current work provides additional evidence that PHA is also a permanent biomarker, potentially useful in retrospective dosimetry. In the Y-12 cohort, the high dose group (n = 5, 2.98-4.61 Gy-Eq) exhibited 13.0 ± 0.85 % Pelger Huët cells (mean ± SEM) in the neutrophil population compared to 6.8 ± 1.6 % in the low dose group (n = 3, 0.29-0.86 Gy-Eq; p = 0.008). An age and gender-matched control group (n = 8) exhibited 3.6 ± 0.9 % PH cells. Results of a one-way ANOVA show that the high dose group is statistically different from both the low dose group and the control group (p = 0.002). In the Y-12 cohort, PHA appears <12 h post-accident and is permanent for more than 16 y. Similar long-term persistence of the PHA mutation has been obtained from examination of peripheral blood slides from the 1971 Co accident at the Variable Dose Rate Irradiation Facility (VDRIF) in Oak Ridge, TN. In order to investigate the pseudo-PH cell as a biomarker in animal studies under well controlled dosimetry, peripheral blood slides were obtained from animals in a nonhuman primate (NHP) (Macaca mulatta) total-body irradiation (TBI) model (Co γ rays at 0.6 Gy min; dose range 1-8.5 Gy, LD50/60 6.44 Gy). In the NHP studies, the first measurement of PHA is taken at 5 h post-irradiation, then daily for days 1-5 and every 5-10 d thereafter. In the TBI model, the PH cell appears quickly (<5 h) post-irradiation, and the dose-dependent PH percentage is constant from 1 d over the 60-d monitoring period of the experiments. Using the average of data from 1-60 d, a linear dose response (PHA % slope = 0.49 ± 0.07 % Gy, r = 0.92) is obtained over the dose range 0-8.5 Gy. The authors conclude that ionizing radiation induces dose-dependent internuclear bridges in circulating neutrophils, and this morphological change can be used both as an acute phase biomarker and as a tool for retrospective dosimetry.

A review of blood diseases and cytopenias associated with human parvovirus B19 infection

Parvovirus B19 is a single-stranded DNA virus which preferentially targets the erythroblast resulting in red cell aplasia, which is temporary in immunocompetent persons. Since the discovery of B19 virus in 1975, a wide variety of blood diseases and cytopenias affecting several blood cell lineages have been documented during or following B19 infection. These include cytopenias affecting the erythroid, megakaryoblastoid, myeloid and lymphoid lineages, as well as a variety of bicytopenias, pancytopenia, bone marrow necrosis / fat embolism syndrome, myelodysplastic syndrome, leucoerythroblastopenia, and hemophagocytic lymphohistiocytosis. B19 infection may also complicate and precede the course of acute leukemia, the significance of which remains to be determined. This review describes the current state of knowledge of the abnormalities of individual blood cell lineages encountered during parvovirus B19 infection, over the almost 40 years since its discovery, and reveals some very interesting themes, which improve our understanding of the pathogenesis of B19 infection with particular reference to the bone marrow.

Pseudo-Pelger-Huët anomaly and granulocytic dysplasia associated with human granulocytic anaplasmosis

Pseudo-Pelger-Huët anomaly (PHA) refers to mono- or bi-lobed granulocytes, reportedly observed in patients with severe infections and inflammation or hematological malignancies including myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML). Dysplastic changes in granulocytes are typical manifestations in MDS and granulocytic leukemias. Here, we report the unique case of a patient found to have human granulocytic anaplasmosis (HGA), a tick-borne disease caused by Anaplasma phagocytophilum, a Gram-negative coccobacillus. This patient showed striking hematological manifestations including a large number of pseudo-PHA, a severe degree of left shift, and dysplastic granulocytes. These hematological presentations on the peripheral smear all resolved with doxycycline treatment, implying that the changes were most likely reactive manifestations secondary to HGA, rather than underlying hematological malignancies such as MDS or AML.

A case report on reversible Pelger-Huët anomaly depending on serum free fraction of valproic acid

Pelger-Huët anomalies, which are characterized by an abnormal nuclear shape and chromatin organization in blood granulocytes, and are frequently confused with myelodysplastic syndrome. We herein report a case of Lenox syndrome in a patient treated with VPA for more than 25 years who developed significant Pelger-Huët anomalies. Despite the lack of any changes in the total VPA level throughout the patient's clinical course, the free fraction of VPA potently increased, likely due to a reduction in serum albumin. Following the administration of a smaller dose of VPA that reduced the serum free fraction of VPA to the normal range, the Pelger-Huët anomalies completely disappeared. It is necessary to monitor the free fraction of VPA in order to detect an overdose, which may induce adverse effects under conditions of hypoalbuminemia. The present case showed, for the first time, that VPA-induced Pelger-Huët anomalies occur in a dose-dependent and reversible manner.

Appearance of pseudo-Pelger Huet anomaly after accidental exposure to ionizing radiation in vivo

To evaluate the morphology of formed elements of human blood after exposure to ionizing radiation in vivo, archival smears of peripheral blood from eight individuals involved in the 1958 Y-12 criticality accident at Oak Ridge, Tennessee, were examined manually by light microscopy. For each case, increased interlobar bridging was observed in nuclei of the myeloid cells, many of which were bilobed and morphologically similar to Pelger Huet (PH) cells. The high-dose group (n = 5, 2.98-4.61 Gy-Eq) exhibited 13.0 ± 0.85% PH cells (mean ± SEM) in the neutrophil population compared to 6.8 ± 1.6% in the low-dose group (n = 3, 0.29-0.86 Gy-Eq; p = 0.008). An age- and gender-matched control group (n = 8) exhibited 3.6 ± 0.9% PH cells. Results of a one-way ANOVA show that the high-dose group is statistically different from both the low-dose group and the control group (p = 0.002). However, the low-dose group is not statistically different from the control group (p = 0.122). The mean number of nuclear lobes in blood neutrophils was also enumerated as a function of time after exposure and was found to be diminished, consistent with incomplete nuclear segmentation that is characteristic of the Pelger Huet anomaly (PHA). In contrast to these changes in myeloid cells, the morphology of erythrocytes and platelets appeared to be normal. The authors conclude that ionizing radiation induces abnormal morphology of circulating neutrophils, which is similar to the pseudo-PHA that is acquired in disorders such as myelodysplastic syndrome, acute myeloid leukemia, and leukemoid reactions. Potential molecular mechanisms by which radiation induces this morphological change are discussed. From this cohort, the biomarker appears to be present early post-accident (<9 h) and stable at least up to 16 y post-accident. Assessment of circulating pseudo-Pelger Huet cells is being investigated as a potential biodosimetric tool.

Hemophagocytic lymphohistiocytosis and pelger-huët anomaly associated with colchicine intoxication

Colchicine is frequently used in the treatment of familial Mediterranean fever (FMF). First symptoms of colchicine intoxication are gastrointestinal disturbances, such as abdominal cramps, diarrhea, pancytopenia and so on. Herein, we report a female FMF patient with pancytopenia and hemophagocytic lymphohitiocytosis (HLH), following colchicine intoxication for committing suicide. To our knowledge, this is the first reported case of a patient with HLH associated with colchicine intoxication.

Acquired myelodysplasia or myelodysplastic syndrome: clearing the fog

Myelodysplastic syndromes (MDS) are clonal myeloid disorders characterized by progressive peripheral blood cytopenias associated with ineffective myelopoiesis. They are typically considered neoplasms because of frequent genetic aberrations and patient-limited survival with progression to acute myeloid leukemia (AML) or death related to the consequences of bone marrow failure including infection, hemorrhage, and iron overload. A progression to AML has always been recognized among the myeloproliferative disorders (MPD) but occurs only rarely among those with essential thrombocythemia (ET). Yet, the World Health Organization (WHO) has chosen to apply the designation myeloproliferative neoplasms (MPN), for all MPD but has not similarly recommended that all MDS become the myelodysplastic neoplasms (MDN). This apparent dichotomy may reflect the extremely diverse nature of MDS. Moreover, the term MDS is occasionally inappropriately applied to hematologic disorders associated with acquired morphologic myelodysplastic features which may rather represent potentially reversible hematological responses to immune-mediated factors, nutritional deficiency states, and disordered myelopoietic responses to various pharmaceutical, herbal, or other potentially myelotoxic compounds. We emphasize the clinical settings, and the histopathologic features, of such AMD that should trigger a search for a reversible underlying condition that may be nonneoplastic and not MDS.