Feline eosinophilic granuloma complex (EGC) is a group of skin diseases that are commonly seen in cats. The appearance of these conditions can be variable, but most often appear as raised, thickened, possibly hairless or ulcerated pink areas. When the disease affects the lip, most often the hair is not lost but the lip becomes very thickened and distended. Lesions are also possible within the mouth, and can be a cause of inappetence in cats.

The causes of the condition are various, and include allergies (to environmental conditions, food, or insects), other infections, and genetic susceptibility. In some cats, stress appears to play a role also. In many cases, the cause of the condition remains a mystery, although an allergy is often suspected. For some reason, female cats appear to be more commonly affected than male cats. It is not known why some cats appear to be susceptible to multiple outbreaks, yet others are never afflicted.

When tissue biopsies of the lesions are obtained, a type of white blood cell, known as an eosinophil, predominates within the lesions. This type of cell may cause the tissue to become very itchy, so affected cats may be seen to scratch or lick excessively at the affected site.

An attempt to determine an underlying cause, particularly an allergy, should be made. Removing a known "trigger" substance or food may then aid in management. Unfortunately, a cause often cannot be identified. Drug therapy, in the form of steroids and/or antibiotics are usually extremely effective in treating most cats, and can sometimes be used to prevent recurrence in some cats. However, side effects from any drug may be seen. It is important to discuss all treatment options with your veterinarian.