WBC Conditions

WBC conditions:

WBCs go haywire too! Historically, morphological characteristics were of utmost importance. At some hospitals a light microscope may have been the best tool available so morphology was critically important. It is still very important to be able to recognize cell types under the scope and nothing can help you more than repetition and practice; however, diagnostic tools like flow cytometry, tumor sequencing, and other molecular techniques are coming to the forefront because the data they are producing is guiding targeted treatments that benefit the patient.

Let’s start to breakdown some common WBC conditions and outline important characteristics of each.

Inherited Neutrophilic Disorders:

Chediak Higashi syndrome:
Chediak Higashi syndrome is a rare inherited condition that presents with giant lysosomal granules that can be in all types of WBCs and platelets, although this condition is most closely associated with neutrophils. They are caused by the fusion of primary and secondary granules. In neutrophils, this fusion causes numerous problems including decreased ability to fight infection.

Pelger Huet anomaly:
Pelger Huet anomaly is a rare inherited condition where the neutrophil nucleus is hyposegmented. The appearance is said to be a “dumbbell shape” (very minor segmentation) when the patient is heterozygous for the condition and “peanut” shaped (no segmentation) when the patient is homozygous.

May Hegglin anomaly:
May Hegglin anomaly is an inherited condition associated with thrombocytopenia, giant platelets, and sometimes neutropenia. Large Dohle body like inclusions will be present.

Alder-Reilly inclusions:
Alder-Reilly is an inherited condition that consists of inclusions of large primary granules similar to those in toxic granulation but larger. The granules consist of precipitated mucopolysaccharides, and can be found in all types of WBCs; whereas, toxic granulation is specific to neutrophils.

Dohle bodies:
Areas of dense RNA in neutrophils

Neutrophils and other WBCs can increase in number due to malignant and non-malignant conditions. In malignant conditions, there will be an increased number of early precursor cells like blasts, promyelocytes, and myelocytes. When they respond to non-malignant conditions like a bacterial infection or inflammation, you will see a “shift to the left” (meaning more precursor neutrophils in circulation) but they will predominantly be band neutrophils and metamyelocytes.

Leukemoid reaction:
Leukemoid reaction refers to how neutrophils are literally reacting. Some reactions neutrophils will have in response to environment are: toxic granulation, Dohle bodies, and vacuolization. There is an old test, leukocyte alkaline phosphatase (LAP) stain, not used anymore that can determine if neutrophils are exhibiting leukemoid reaction or a condition like CML. The test was based around the fact that normal neutrophils would be high in the LAP enzyme; whereas, abnormal neutrophils seen in CML would be low or deficient in LAP.

Study Tip
You may encounter a problem for calculating the LAP score. The test gives a group of neutrophils a score between +1 and +4 based on their amount of the enzyme LAP. The test has been replaced due to molecular and genetic tests but it’s good to be aware of the calculation, and the calculation is easy. You simply add the score of all 100 cells together. Usually you will get the amount of each score, e.g. (20 1+, 25 2+, 40 3+, 15 4+). Simply multiply the amount of cells in each category by the LAP score to get the total score. A score of 20-100 is normal.