Hyperleukocytosis is defined as an increase in white blood cells above 10 cells per microliter of blood, in two successive examinations. Frequently encountered anomaly, a distinction should be made between benign hyperleukocytosis and malignant hyperleukocytosis. The latter may be the sign of a bacterial infection such as angina, of a viral infection such as mononucleosis and more rarely of a serious pathology such as leukemia. Symptoms and management of hyperleukocytosis depend on the context and its cause.

Leukocytes, also called white blood cells, play an important role in our body’s defense against infectious microorganisms and foreign substances. To be effective, an adequate number of white blood cells must be made aware of the presence of the infectious organism or foreign substance. They then go to where they are, to destroy and digest them.

• neutrophils;
• lymphocytes;
• monocytes;
• eosinophils;
• basophils.

Normally, a person produces around 100 billion white blood cells per day. These are counted as the number of white blood cells per microliter of blood. The total normal number is between 4 and 000 cells per microliter.

Hyperleukocytosis is an increase in the number of white blood cells in the blood, above 10 cells per microliter of blood. Hyperleukocytosis is described as moderate between 000 and 10 white blood cells per microliter of blood and frank above 000 white blood cells per microliter of blood.

• polynucleosis when it comes to an increase in the number of neutrophils, eosinophils or basophils;
• lymphocytosis when it is an increase in the number of lymphocytes;
• monocytosis when it comes to an increase in the number of monocytes.

There may also be hyperleukocytosis resulting from the appearance of cells normally absent from the blood:

• medullary cells, that is, cells formed by the marrow and which, in the stages of immaturity, pass into the blood;
• malignant cells or leucoblasts which are indicators of acute leukemia.

Hyperleucocytose

Hyperleukocytosis can be said to be physiological, that is to say normal:

• following physical exertion;
• after significant stress;
• during pregnancy;
• in the post-delivery.

But, in most cases, hyperleukocytosis is the body’s normal defense response to:

• bacterial infection such as bacterial streptococcal angina;
• viral infection (mononucleosis, cytomegalovirus, hepatitis, etc.);
• parasitic infection;
• an allergy (asthma, drug allergy);
• certain medications such as corticosteroids.

More rarely, hyperleukocytosis can be a sign of bone marrow cancer, causing the release of immature or abnormal white blood cells from the bone marrow into the blood, such as:

• chronic lymphocytic leukemia (CLL);
• chronic myelogenous leukemia (CML);
• acute leukemia.

Polynucléose

Regarding neutrophilic polynucleosis, it is seen in certain physiological states such as:

• the birth ;
• the pregnancy ;
• the period ;
• violent exercise;

and especially during pathological conditions such as:

• a microbial infection (abscess or sepsis);
• inflammatory disease;
• tissue necrosis;
• cancer or sarcoma;
• smoking.

Eosinophilic polynucleosis, on the other hand, has two main causes: allergy and parasites. It can also be linked to periarteritis nodosa, Hodgkin’s disease or cancer.

Basophilic polynucleosis is very rare and is seen in chronic myeloid leukemia.

Lymphocytose

Hyperlymphocytosis is recognized:

• in children during infectious viral or bacterial diseases such as whooping cough;
• in adults or the elderly with chronic lymphocytic leukemia and Waldenström’s disease.

Monocytose

Monocytosis often reveals an infectious disease:

• infectious mononucleosis ;
• toxoplasmosis;
• cytomegalovirus infection;
• viral hepatitis ;
• brucellosis;
• Osler’s disease;
• secondary syphilis.

The symptoms of hyperleukocytosis will be those of the disease from which it results. For example, with a viral infection, such as mononucleosis, symptoms include:

• fever ;
• lymph nodes in the neck;
• severe fatigue.

The management depends on the context and the cause of the hyperleukocytosis. It therefore varies depending on whether it is due to angina, pneumonia or chronic lymphoid leukemia.

• symptomatic treatment for viral infections;
• antibiotic treatment for bacterial infections;
• antihistamine treatment in case of allergies;
• chemotherapy, or sometimes a stem cell transplant, in case of leukemia;
• the removal of the cause in case of stress or smoking.