Hypereosinophilic syndrome (HES) is a group of rare, often chronic disorders characterized by the overproduction of eosinophils, which are a type of white blood cell. This overproduction, known as eosinophilia, can occur in various parts of the body, leading to a wide range of symptoms and complications. These can include skin rashes, asthma-like symptoms, heart complications, and neurological problems. The severity and progression of HES can vary greatly from one person to another.
Types of Hypereosinophilic Syndrome
There are several types of hypereosinophilic syndrome, which are primarily classified based on the underlying cause and the parts of the body affected. These include:
- Primary HES: This is also known as clonal HES. It is caused by a mutation in the bone marrow cells that produce eosinophils. This leads to an overproduction of eosinophils.
- Secondary HES: Also known as reactive HES, this type is caused by an underlying disease or condition that triggers an overproduction of eosinophils. Common causes include certain types of cancer, autoimmune diseases, and parasitic infections.
- Idiopathic HES: In this type, the cause of the eosinophilia cannot be determined despite thorough investigation. It is thought to be due to an unknown trigger that causes the immune system to produce too many eosinophils.
Why Do People Get Hypereosinophilic Syndrome?
The exact cause of hypereosinophilic syndrome is not fully understood. It is thought to be due to a combination of genetic and environmental factors. In primary HES, a mutation in the bone marrow cells leads to an overproduction of eosinophils. In secondary HES, an underlying disease or condition triggers the overproduction. In idiopathic HES, the cause is unknown. Risk factors for HES may include a family history of the disorder, exposure to certain environmental toxins, and having an autoimmune disease. However, more research is needed to fully understand why some people develop HES while others do not.