Leukocyte (WBC) Disorders

Flashcards covering key vocabulary related to leukocyte (WBC) disorders, their definitions, and associated clinical conditions.

Leukocyte (WBC) Disorders

A broad category covering abnormalities in white blood cell numbers or function.

-penia

A suffix indicating a decrease in cell numbers.

-philia / -cytosis

A suffix indicating an increase in cell numbers.

Leukocytosis

An increase (above reference range) in the number of WBC's in circulation due to any cause.

Leukopenia

The reduction in the number of WBC's in circulation.

Left Shift

The appearance of increased numbers of immature WBC's in blood circulation (e.g., Band cells).

Regenerative Left Shift

An increased white cell count and increased number of immature WBCs in circulation where mature cells outnumber immature cells, indicating an early response to increased demand.

Degenerative Left Shift

Normal or low white cell count with immature cells out-numbering mature cells, usually with toxic changes, indicating the ability to produce cells is less than the demand (e.g., severe infection, sepsis).

Toxic Changes (Neutrophils)

Changes seen in immature neutrophils released from bone marrow due to severe inflammation, including Cytoplasmic Basophilia, Toxic Granulation, Toxic Vacuolation, Dohle Bodies, and Nuclear Immaturity.

Toxic Granulation

Blue staining (basophilic) granules in neutrophils, indicative of toxic changes.

Toxic Vacuolation

Irregular clearings in the cytoplasm of neutrophils, appearing 'foamy' or moth-eaten, indicative of toxic changes.

Dohle Bodies

Light blue rod-shaped remnants of RNA in the cytoplasm of neutrophils, indicative of cytoplasmic immaturity, most common in cats.

Benign Quantitative WBC Disorder

Abnormalities in leukocyte number that are changes in number only, possibly part of a good immune or inflammatory response.

Malignant Quantitative WBC Disorder

Abnormalities in leukocyte production where abnormal cells are present, such as in leukemia.

Margination

The process where leukocytes become sticky and adhere to the inside wall of a blood vessel before migrating to tissues.

Marginated Pool

The population of leukocytes sticking to the inside wall of blood vessels, waiting to migrate to tissues.

Neutrophilia

An increase in the absolute number of neutrophils in circulation above normal for that species.

Physiologic Neutrophilia

A short-term, generally mild increase in neutrophils due to endogenous epinephrine release, causing cells to shift from the marginated pool to the circulating pool; no left shift or toxic changes are seen.

Stress Neutrophilia

An increase in mature neutrophils due to endogenous release of corticosteroids (cortisol), which prevents neutrophils from moving from the circulating pool to the marginated pool and tissues, leading to increased production and release from the bone marrow.

Stress Leukogram

A classic pattern of leukogram changes associated with stress, characterized by neutrophilia, lymphopenia, and eosinopenia.

Inflammatory Neutrophilia

An increase in neutrophils resulting from an actual increased demand for phagocytic cells at the tissue level, often accompanied by a left shift, toxic changes, and monocytosis.

Monocytosis (associated with inflammation)

An increase in monocytes, often seen with longer-standing or resolving inflammation as they move into 'mop up' mode and become macrophages in tissues.

Neutropenia with Left Shift (Dog/Cat)

A concerning condition in dogs and cats where overwhelming inflammation causes the bone marrow to be unable to keep up with demand, resulting in a low neutrophil count despite immature cells being released.

Neutropenia with Left Shift (Cattle/Horses)

A change commonly seen in cattle and horses at the beginning of an infection due to their smaller bone marrow storage pool, where neutropenia may be an expected indicator of inflammation/infection, not necessarily overwhelming concerns.

Monocytosis

An absolute increase in monocytes, typically seen with longer-standing or resolving inflammation and often indicating an appropriate and improving response if following a left shift.

Eosinophilia

An increase in the absolute number of eosinophils, potentially caused by GI disease, parasitic infections, or allergic reactions.

Lymphocytosis

An absolute increase in the number of lymphocytes, can be physiologic (short-lived fear/excitement) or pathologic (neoplasia, viral conditions), but not a common finding.

Lymphocytopenia

A decrease in the absolute number of lymphocytes, very common in veterinary medicine, often due to hereditary/acquired immunodeficiency or endogenous corticosteroids (stress leukogram).

Leukopenia

Decreased numbers of WBCs below the normal reference range, which may be driven by a decrease in only one population (e.g., neutropenia, lymphocytopenia).

Panleukopenia

A condition where a process wipes out all WBCs being produced in the bone marrow.

Neutropenia

A decrease in neutrophils, which generally results in leukopenia, caused by increased demand, reduced/ineffective production, or sequestration.

Neutropenia (Increased Demand)

Occurs with a degenerative left shift in acute infection or severe inflammation where the bone marrow is overwhelmed by demand and cannot keep up.

Neutropenia (Reduced Production)

Occurs when bone marrow fails to produce adequate numbers, evident first in neutrophils due to their short half-life, and takes time to develop (e.g., canine Parvovirus, Feline Panleukopenia Virus).

Neutropenia (Ineffective Production)

An uncommon condition caused by bone marrow malfunction where cells are produced but normal cells are not arriving in circulation, either due to destruction in the marrow or incorrect maturation.

Neutropenia (Sequestration)

A sudden, transient migration of neutrophils to the marginated pool, causing a decrease in the circulating blood pool (e.g., anaphylactic shock and endotoxemia).

Leukemia

An abnormal proliferation of WBCs with increased numbers of very immature cells, a type of malignant quantitative WBC disorder.

Lymphoproliferative Disorders

Malignant proliferation of the lymphoid system which arises in lymphoid organs other than bone marrow (e.g. malignant lymphoma or Lymphosarcoma).