The term eosinophilic granuloma complex (EGC) refers to a group of skin lesions that represent an allergic reaction in the cat's skin. These occur in three forms, and your cat may have any or all of them. These forms include: Eosinophilic granulomas. These nodules are raised, yellow or pink in color, and usually are not itchy. They occur on the back of the rear legs, in and around the mouth and on the face and are most common in adolescent kittens.
Eosinophilic plaque. These patches look like a raised, round red lesions that may be ulcerated. They are usually itchy and are most commonly found on the belly, inner thigh or throat.
Indolent ulcer. Erosions on the margin of the upper lip and sometimes on the tongue are red in color and glistening in appearance. They may be painful and may affect the cat's willingness to eat.
On microscopic examination of skin biopsy specimens, all of these forms of the disease are characterized by accumulation of large numbers of eosinophils, a type of white blood cell found in allergic and parasitic inflammatory disorders.
A common cause is thought to be flea allergy, but atopy, a form of allergy triggered by inhaled environmental allergens such as pollens and dust, and food allergies also can cause EGC lesions in cats. An allergic response to mosquitoes is also suspected.
Female cats may be more likely to be affected than male cats, but only rarely is it found in dogs, such as Siberian huskies.
Diagnostic tests may be needed to diagnose eosinophilic granuloma complex and assess the extent of the disorder and its effects on the cat. Often, a presumptive diagnosis is made based on the clinical appearance of the lesions and their response to treatment. Tests may include:
A complete medical history and physical examination. Physical examination is very important because of the distinctive clinical appearance of the lesions.
A complete blood count (CBC or hemogram) to evaluate for anemia, infection, inflammation and circulating eosinophils
Skin biopsy to rule out other causes of lesions with a similar appearance – most notably skin cancers such as squamous cell carcinoma or cutaneous lymphosarcoma. The results of the skin biopsy will confirm the diagnosis of eosinophilic granuloma complex.
Treatment for eosinophilic granuloma complex may include one or more of the following:
Corticosteroids. Cortisone-like drugs are used most commonly to treat cats with suspected eosinophilic granuloma complex. Unlike other feline skin reactions such as miliary dermatitis, the lesions of eosinophilic granuloma complex rarely respond to removal of the allergen alone. The anti-inflammatory effects of corticosteroid drugs such as prednisone and methylprednisolone acetate are usually needed.
Flea control, elimination diets to identify food allergens, and treatment for inhaled allergens (those that cause atopy) may help prevent recurrence.
Home Care and Prevention
At home, administer as directed all medications prescribed by your veterinarian, and contact your veterinarian if you are having difficulty medicating your pet or if the condition has worsened.
Follow-up appointments are very important because the lesions of eosinophilic granuloma complex often require more than one treatment for complete success.
Preventative measures include flea control, elimination diets to identify food allergens and treatment for inhaled allergens.