Fredrick L. Kiechle, MD, PhD
Q. What should the CLS practitioner call hyperclumped pelgeroid neutrophils that are non-segmented? Should they be called band neutrophils, segmented neutrophils, or something else? If they are called bands, physicians may treat the patient for an infection if a comment about pelgeroid maturation is not noticed. If they are called segs, that goes against the CAP definition of a seg having a filament. Does the answer change if the patient has the Pelger-Huët anomaly instead of pelgeroid maturation?
A. Most hematologists are familiar with the typical “pince-nez” eyeglass appearance of the Pelger-Huët neutrophil. These are the predominant type of neutrophil in patients who are heterozygous for the Pelger-Huët anomaly, which has an autosomal dominant pattern of inheritance of a mutation in the lamin B receptor (LBR) gene.1 Given the presence of a filament between the two lobes, they are easily classified as a segmented neutrophil on the differential count. In our laboratory, we would also list a morphology comment noting the Pelger-Huët appearance.
Less frequently, one may observe a neutrophil with a single round nucleus, often eccentrically placed with coarsely clumped chromatin. There is little or no nuclear segmentation, and these cells can be confused with myelocytes or nucleated erythrocytes. This is the typical cell seen in patients with homozygous Pelger-Huët anomaly, which is rare and may be associated with skeletal anomalies, developmental delay, and seizures.1 One can also see this type infrequently in the patient with heterozygous Pelger-Huët anomaly, in which the majority of the neutrophils are of the “pince-nez” type. In our laboratory, we would count these cells as “band” neutrophils in the differential count, with a morphology comment noting the change, so that the physician doesn’t misinterpret the band count as a sign of infection. Another alternative would be to send these cases to the pathologist for review. She or he can then make sure that an appropriate consultation occurs and is reported to inform the physician of the significance of this finding.
In addition, both of these cell types can be seen occasionally in patients with dysplastic myeloid features, including myeloid leukemias, myelodysplastic syndromes, and other leukemic processes. They have also been seen in patients taking sulfonamide, colchicine, and mycophenolate mofetil; in patients with HIV; and in patients with mycoplasma pneumonia.2 In these settings, the number of affected nuclei is variable and they are typically designated pseudo-Pelger-Huët2 or “pelgeroid” cells.
The importance of recognizing these nuclear features resides in their occurrence in the setting of myeloid dysplasia. If “pelgeroid” features are noted, the smear should be carefully examined for other features of dysplasia, including, for example, hypogranularity, abnormal cell size, and immature cells. Dysplastic features in erythrocytes and platelets should also be noted. This is an opportunity to identify a patient with a significant bone marrow abnormality. Therefore, it is important to recognize any dysplastic features that may be present and report these findings to the ordering physician. This is another reason to have these cases reviewed by a pathologist, who can evaluate the case for dysplastic findings, consult with the ordering physician, and generate a report if needed.
1. Kanwar VS. Pelger-Huet anomaly. Medscape Web site. http://emedicine.medscape.com/article/957277-overview. Accessed Jan. 18, 2012.
2. CAP Hematology/Clinical Microscopy Resource Committee. 2011 Hematology, Clinical Microscopy, and Body Fluids Glossary; 2011.
3.Glassy EF, ed. Color Atlas of Hematology: An Illustrated Field Guide Based on Proficiency Testing.Northfield, Ill.: College of American Pathologists; 1998.
Katherine A. Galagan, MD
Director, Clinical Laboratories
Virginia Mason Medical Center
Why is it that assessment of the FLT3 mutation by PCR cannot be performed on formalin-fixed, paraffin-embedded tissue? We’ve had cases where it would have been nice to have been able to assess for the FLT3 mutation on the paraffin-embedded aspirate clot. I’ve checked with several send-out labs, and none can perform FLT3 mutational analysis on paraffin-embedded tissue.
A. The FLT3 ITD amplicon length for wild types is about 330 bp for most laboratories using published primer sets. This is very close to the maximum size that is amplifiable from formalin-fixed tissues due to DNA degradation from the fixation.1 That is why most reference laboratories do not accept formalin-fixed clot sections for this test. Bone marrow core biopsies are even more challenging. Cores are almost always decalcified by treatment with a fairly strong acid solution. The acid treatment severely degrades any DNA in the sample, rendering it useless for many molecular techniques.
I think that scraping cells from unstained marrow aspirate smears may be possible for this test. But the reference laboratories will have to optimize their DNA extraction protocol for this type of sample. Also, laboratories that perform next-generation sequencing may be able to use paraffin-embedded tissue for the test as well.
1. Shi SR, Cote RJ, Wu L, et al. DNA extraction from archival formalin-fixed, paraffin-embedded tissue sections based on the antigen retrieval principle: heating under the influence of pH. J Histochem Cytochem. 2002;50:1005–1011.
Chung-Che (Jeff) Chang, MD, PhD
Professor of Pathology
University of Central Florida
College of Medicine
Medical Director for Hematology and Molecular Pathology
Department of Pathology
Member, CAP Molecular Oncology Resource Committee
Given that a high percentage (30 to 40 percent) of oral squamous cancers are HPV related, and that many of these lesions could be detected at an early preinvasive stage (curable with photodynamic therapy), why does the CAP not encourage otolaryngologists and dentists to screen high-risk patients for oral cancer precursors?
The CAP does not routinely issue directives to pathologists’ clinical colleagues regarding their practices in general, much akin to how the CAP does not issue guidelines about how often or when a person should be screened for colon cancer or when a woman should get a Pap test or mammogram. The CAP and its members concern themselves with pathology practice, not with what dentists or otolaryngologists do and do not do. We have collaborated on issues that involve pathology services directly, and the HER2/neu and ER/PgR guidelines and the forthcoming lung cancer biomarkers guideline are examples. However, those guidelines apply only to what happens once a specimen is obtained and do not direct the clinicians in terms of patient screening or when a biopsy should be done. Screening recommendations generally come from the respective clinical organizations.
Mary Beth Beasley, MD
Mt. Sinai Medical Center
New York, NY
Chair, CAP Surgical
Dr. Kiechle is medical director of clinical pathology, Memorial Healthcare, Hollywood, Fla.