Third Street Veterinary Hospital, PC
McMinnville, Oregon 97128
Office phone: (503) 472-9418
Eosinophilic
Granuloma Complex
The
eosinophilic granuloma complex is a group of diseases that appear to be
related. They causes are distinct lesions
on the skin that respond to the same treatment; this is one of the reasons that
they are grouped together as a "complex." The name is somewhat misleading because not all variations of the
lesions contain eosinophils (a type of white blood cell).
Eosinophils
are normal blood cells that are part of the body's immune system. Their numbers increase in certain diseases,
including allergies and parasites. They
are also found in high numbers in a few other diseases but are typically not
related to cancer.
Prevalence
Lesions
of the eosinophilic granuloma complex are relatively common in the cat.
Clinical Signs
There
are three rather distinct types of lesions in the eosinophilic granuloma
complex: 1) rodent (indolent) ulcer, 2) eosinophilic plaque, and 3) linear
(collagenolytic) granuloma.
A
rodent ulcer (indolent ulcer) begins as an ulcerated area on the upper lip
between the large canine teeth. As it
increases in size, the upper lip may become swollen and very painful. It is named a "rodent" ulcer because
there was a belief that mice and rats were biting the cat's upper lip as they
were being attacked. However, this
problem has nothing to do with rodents.
The
eosinophilic plaque is a round to oval area on the skin that is very red and
inflamed. These lesions are
characterized by intense itching. Hair
is often lost over the area possibly due to licking by the cat. These lesions may be 1" to 4"
across and usually occur on the ventral abdomen (belly). They are sometimes accompanied by smaller
lesions on the bottom of the feet or in the mouth.
The
linear (collagenolytic) granuloma is usually a raised, rope-like lesion along
the rear aspect of the upper part of the back legs; however, it may occur in
other locations as well. It may be
1/4" to 1/2" across and several inches long. In some cats, it presents as a swollen or
“fat” chin. It is non-painful, and the
hair usually does not fall out around or over it. Owners often find it as they pet or hold their cat.
Causes/Transmission
Animal
dermatologists believe that, in most cases, these lesions are rooted in an
allergic reaction. In particular, the
lesions may be a response to food allergy, fleabite allergy, or inhalant
(hayfever-type) allergy.
Diagnosis
Each
of the three diseases has a characteristic appearance and can often be
diagnosed just from that. If the
diagnosis is not certain, a biopsy may be performed. A biopsy of the eosinophilic plaque reveals a large number of
eosinophils. The other two forms may or
may not have eosinophils present, but the pathologist can identify other
characteristics that make the diagnosis.
Treatment
Each
of these diseases responds well to corticosteroids ("steroids" or
"cortisone"). The injectable
forms of steroids are usually more effective than steroid tablets. Response should begin within one day and
near-recovery should occur within one week.
The steroid injection may need to be repeated in 3-4 weeks for a
complete response.
Some
of these lesions are infected with skin bacteria. Therefore, antibiotics may be part of the treatment.
A
cat with a rodent ulcer may be having a contact allergy to the food bowl. There are anecdotal reports of cure just by
changing from plastic bowls to glass, porcelain, or stainless steel bowls. Since this is a simple thing to do, it
probably should be tried if your cat eats or drinks out of a plastic bowl.
Prognosis
Unfortunately,
most of these diseases recur when the injection of steroids has dissipated;
this usually takes 3-4 weeks. Repeated
injections may be needed, although some occur just in certain parts of the
year. Many cats can be controlled
long-term with oral steroids if the tablets are preceded by an injection.