Definition
Definition
An increase in the blood eosinophil count above 0,02 and 0,5 x 10² per cubic millimeter of blood. It is important to know that it is the number, not the percentage, that matters.
Classification
Idiopathic hypereosinophilic syndrome, also known as eosinophilic connective tissue disease or Hardy-Anderson syndrome, is a condition whose cause is not precisely known and characterized by a marked increase in a variety of white blood cells: eosinophilic polymorphonuclear cells in the blood for a period exceeding six months. Other symptoms include damage to certain systems (digestive, nervous, etc.) or organs (in this case, we speak of systemic disease), more specifically the heart, spleen, and liver.
The causes of idiopathic hypereosinophilic syndrome are not yet known. It may be a myeloproliferative syndrome (multiplication of blood cell precursors) as can be seen in eosinophilic leukemia. It may also be a hypersensitivity syndrome with hypergammaglobulinemia mainly affecting immunoglobulin E and circulating immune complexes or a genetic abnormality such as the fusion of the PDGSRB-ETV6 genes (locus 5q31-q33) or the PDGFRA-FIP1L1 genes (locus 4q12).
Patients affected by this condition present (non-exhaustive list):
- Asthenia (intense fatigue).
- Anorexia (loss of appetite).
- Myalgia (muscle pain).
- A low fever.
- Some patients experience impaired cardiac pump function with arrhythmia (heart rhythm disturbances) and inflammation of the heart chambers (such as Löffler's endocarditis).
- A cough that is more prevalent at night.
- A skin rash.
- One or more edemas (angioedema).
- Other symptoms are possible, including damage to the central nervous system, specifically the peripheral nerves, eye damage, joint damage, or the digestive system. These symptoms are the result of complications related to a coagulation disorder resulting in the presence of emboli or microthrombosis (the appearance of a blood clot) within the body's tiny vessels.
The patient's examination revealed hepatomegaly (enlarged liver), splenomegaly (enlarged spleen) associated with adenopathies (presence of abnormal lymph nodes).
Further examinations, and more specifically the X-ray, show what specialists call a diffuse infiltrative syndrome visible on chest X-rays.
Blood tests show an increase in the number of eosinophils and the presence of eosinophils which have particular characteristics: they have become vacuolated.
Thrombocytopenia (decrease in the number of platelets) and hypergammaglobulinemia, i.e. an increase in gamma globulins (mainly immunoglobulin E), are also observed relatively frequently.
Idiopathic hypereosinophilic syndrome should not be confused with secondary eosinophilia, especially when the patient has parasitosis (disease caused by a parasite), eosinophilic leukemia, Sézary disease, or T-cell lymphoma.
The prognosis for this hematological condition (blood disease), without treatment, is, as far as treatment-resistant forms are concerned, poor in about a year.
One in two patients, however, improves with the administration of cortisone (corticosteroids) and four out of five patients, when properly treated, have a prolonged survival.
Treatment for idiopathic hypereosinophilic syndrome includes corticosteroids such as prednisone at a dose of 1 milligram per kilogram per day for two months. If eosinophilia persists, hydroxyurea at a dose of 0,5 to 1,5 g per day in tablet form (orally) is then added.
If treatment fails, interferon alpha 2B is sometimes offered.
A form of hypereosinophilic myalgic syndrome has been described following the ingestion of foods containing L-tryptophan. This type of syndrome is characterized by the appearance of pain and a rash (fleeting eruption). Some patients also experience a loss of elasticity in certain areas of the skin (cutaneous induration) comparable to that observed in scleroderma.
Dress syndrome (Drug Rash with Eosilophilia and Systemic Symptoms), also known as drug hypersensitivity, is a syndrome characterized by the appearance of a transient skin rash and hypereosinophilia associated with a significant amount of eosinophils in the blood. Tests sometimes show an eosinophil count above 1500 cells per microliter. This syndrome most often occurs following drug absorption.
Symptoms
physiology
Eosinophils are a type of white blood cell characterized by their large, multi-lobed nuclei containing large granules that are easy to stain with a dye called eosin. This is an acidic dye derived from fluorescein and is pink in color and used in hematology (blood diseases), histology (tissue studies), and dermatology to disinfect wounds.
Eosinophilia is the term incorrectly used to describe an increase in the number of eosinophils in the blood.
Eosinophilic granulocytes are rounded and approximately 15 µm in diameter. They are slightly larger than neutrophilic granulocytes (another type of white blood cell).
In their cytoplasm (liquid surrounding the nucleus), the granulation is dense. These grains appear as a bright red color tending towards honey yellow.
The nucleus usually has two lobes.
Role
Their role is not precisely known. However, they play an undeniable role in their ability to destroy parasites. This type of white blood cell has the ability to phagocytose (they are able to trap foreign particles as well as microbes), like neutrophils. They also have the ability to migrate.
Pathophysiology
Eosinophilia is a misnomer used by the medical profession and usually refers to an increase in the number of eosinophils in the blood.
Eosinopenia is, on the contrary, a decrease in the number of eosinophils.
The diagnosis of hypereosinophilia is observed in certain pathologies (non-exhaustive list):
- Allergy.
- Parasitosis (helminth, threadworm in children). Other parasitoses such as those occurring during malaria do not cause hypereosinophilia.
- Eczema.
- Hay fever.
- Asthma.
- Pemphigus.
- Malignant tumors: Hodgkin's disease, lung, stomach, pancreatic, ovarian, and uterine cancer.
- Blood diseases (hemopathies).
- Myeloproliferative syndrome (form of chronic leukemia).
- Chronic myeloid leukemia.
- Systemic disease such as connective tissue disease (collagen disease) and more specifically periarthritis nodosa: in this case, the sedimentation rate is high.
- Rheumatoid arthritis.
- Granulomatosis.
- Polyarteritis nodosa.
- Fasciitis with hypereosinophilia.
- Certain treatments with antibiotics (penicillin, sulfonamides, cephalosporins) or other medications (iodine, aspirin, nitrofurantoin). During the intake of cytokines (such as IL-2 and GM-CSF), transient hypereosinophilia is observed.
- Inflammatory disease of the vessels (allergic angiitis).
- Ofugi's disease: This is a disease also called eosinophilic pustulosis. This condition is characterized by the appearance of papules (small, slightly raised patches) and pustules (crusts of pus) grouped together in patches and located mainly on the face. The disease progresses in flare-ups lasting approximately 2 weeks. Healing then occurs spontaneously. There is an increase in the level of eosinophils in the blood and the penetration of eosinophils into the sebaceous glands (glands secreting an oily liquid in the skin). Eosinophils also penetrate (infiltration) the dermis (layer of cells located below the epidermis).
- Job syndrome.
- Löffler's endocarditis: very significant increase in eosinophils (between 50 and 000 per microliter).
Please note:
It is possible to diagnose a tissue eosinophil infiltrate (passage of eosinophils into certain tissues of the body) without necessarily demonstrating any elevation in the level of eosinophils in the blood.
Treatment
Treatment
That of the cause.