Hypereosinophilic Syndrome – Symptoms and Causes
Overview
Hypereosinophilic syndrome (HES) is a group of rare blood disorders characterized by abnormally high levels of eosinophils in the blood. Eosinophils are white blood cells that help fight infections and play a key role in the immune system.
When these cells accumulate in excessive numbers, they can infiltrate various organs and tissues.
The condition can affect multiple body systems, particularly the:
- Skin
- Lungs
- Digestive system
- Heart
- Blood vessels
- Nervous system
Without proper treatment, the organ damage caused by HES can become severe and potentially life-threatening.
Symptoms
Hypereosinophilic syndrome (HES) causes different symptoms depending on which organs are affected by high levels of eosinophils. Many people experience fatigue and general weakness as their first signs of illness.
Common symptoms include:
- Fever
- Cough
- Shortness of breath
- Muscle pain
- Rash or itchy skin
- Dizziness
- Memory problems
When HES affects the heart, patients may feel chest pain, experience irregular heartbeats, or develop heart failure. Lung involvement often causes coughing, wheezing, and breathing difficulties similar to asthma.
Digestive system symptoms include:
- Abdominal pain
- Diarrhea
- Nausea
- Vomiting
- Unexplained weight loss
Some people develop skin problems like rashes, hives, or swelling. Nervous system issues may cause confusion, memory loss, numbness in limbs, or vision changes.
Blood clots are another possible complication, potentially leading to stroke or deep vein thrombosis. Some patients show few or no symptoms at first, with the condition found only during routine blood tests.
Causes
The exact triggers of hypereosinophilic syndrome (HES) remain unclear in many cases. This rare blood disorder happens when the body produces too many eosinophils. These excess cells build up in blood and tissues, leading to inflammation and organ damage.
Medical experts classify HES into several types based on what causes the high eosinophil count:
- Primary (Neoplastic) HES: Caused by genetic changes in bone marrow cells that lead to abnormal growth and development of eosinophils.
- Secondary (Reactive) HES: Results from the body’s response to allergies, parasitic infections, or other conditions that trigger eosinophil production.
- Idiopathic HES: Cases where doctors cannot identify a specific cause despite thorough testing.
Certain genetic abnormalities can play a role in some forms of HES. For example, about 10-15% of patients have a genetic change called FIP1L1-PDGFRA. This mutation creates an abnormal protein that signals bone marrow to produce too many eosinophils.
Some people develop HES due to their immune system overreacting. In these cases, abnormal T cells (a type of white blood cell) release substances that stimulate eosinophil growth.
Risk Factors
Several factors may increase a person’s chance of developing this condition.
Age and gender play a role in who gets HES. The condition most often affects people between 20 and 50 years of age. Men develop HES more frequently than women, though we don’t fully understand why.
Genetic factors contribute to certain types of HES. Some forms run in families, suggesting inherited genetic mutations may increase risk. Specific genetic abnormalities, particularly those affecting certain chromosomes, have been linked to HES development.
Other blood disorders may increase risk. People with certain myeloproliferative disorders have a higher chance of developing HES.
Allergic and immune conditions might be connected to HES risk. Those with histories of severe allergies, asthma, or autoimmune disorders sometimes show higher rates of HES.
Environmental triggers like certain medications, infections, or toxin exposures have been documented in some cases, though these connections aren’t fully established.
Many people develop HES without any clear risk factors, making it difficult to predict who will get this rare condition.
