Eosinophilic Granuloma Complex

Eosinophilic Granuloma Complex (EGC) is a term used to describe a group of inflammatory skin conditions in cats that are characterized by the presence of eosinophils, a type of white blood cell involved in allergic reactions and parasitic infections. EGC is not a single disease but rather a group of related conditions that manifest in different ways, often as skin lesions or sores. The exact cause of EGC is not always clear, but it is commonly associated with allergic reactions, such as those to fleas, food, or environmental factors.

The Three Main Forms of EGC

1. Eosinophilic Plaques:
   • Appearance: Raised, red, and often ulcerated or moist areas of the skin.
   • Location: Commonly found on the abdomen, inner thighs, or other parts of the body where the cat can easily lick or scratch.
   • Symptoms: These plaques are usually itchy, causing the cat to scratch or lick the affected area excessively.
2. Eosinophilic Granulomas:
   • Appearance: Linear or nodular lesions that may have a yellowish, pink, or white appearance.
   • Location: Often found on the back of the legs, inside the mouth, on the lower lip (causing a “fat lip” appearance), or on the tongue.
   • Symptoms: These lesions may or may not be itchy. Granulomas in the mouth can cause difficulty eating and drooling.
3. Indolent Ulcers (Rodent Ulcers):
   • Appearance: Ulcers or sores, typically found on the upper lip.
   • Location: Usually affects the upper lip, but can also appear on the tongue or hard palate.
   • Symptoms: These ulcers are usually not painful, but they can become chronic and resistant to treatment.

Causes of EGC

The exact cause of EGC is often idiopathic, meaning it may not be linked to a specific underlying condition. However, common triggers include:

• Allergies: Flea bites are the most common trigger, but food allergies or environmental allergens (such as pollen or dust mites) can also be involved.
• Infections: Bacterial, viral, or fungal infections may trigger or worsen EGC lesions.
• Immune System Dysfunction: EGC is sometimes considered an autoimmune disorder, where the cat’s immune system overreacts to a perceived threat.

Diagnosis

Diagnosis of EGC is based on the cat’s clinical signs, medical history, and the appearance of the lesions. Additional tests that may be performed include:

• Skin Biopsy: To confirm the presence of eosinophils and rule out other conditions.
• Allergy Testing: To identify potential allergens that may be triggering the condition.
• Blood Tests: To check for underlying health issues that could contribute to EGC.

Treatment

Treatment for EGC focuses on managing the symptoms and addressing the underlying cause:

• Corticosteroids: These are the most common treatment and work by reducing inflammation and suppressing the immune response.
• Antibiotics: If a secondary bacterial infection is present, antibiotics may be prescribed.
• Flea Control: Rigorous flea control is essential, as flea allergy is a common trigger for EGC.
• Hypoallergenic Diet: If food allergies are suspected, a hypoallergenic diet may be recommended.
• Immunosuppressive Drugs: In cases where corticosteroids are not effective, other immunosuppressive drugs like cyclosporine may be used.

Prognosis

The prognosis for cats with EGC is generally good, especially if the underlying cause can be identified and managed. However, some cats may experience recurrent episodes throughout their lives, requiring ongoing treatment and monitoring.

---