What Is This Lump on My Cat?

CatChannel veterinary expert Arnold Plotnick, DVM, discusses the possible causes of mysterious lumps on cats.

Q: My cat, Sophie, has two lumps that are flat with white dots on them located in the back of her throat. A local vet said she has never seen these before and does not know what they can be. Sophie had a small, pea-sized round lump in a different spot in her mouth three years ago. I had it removed, but the vet lost the mass so it was not tested.

Do you have any idea what they can be? The new vet said she could remove the lumps. I don’t want to put Sophie through this. Sophieís a very, very scared cat. She’s 15 years old and has never been away from home except when she was spayed 14 years ago and, I took her home the same day. This current vet thinks I’m being over protective. But I, being a very multiple cat household, know what stress can do. Sophie also currently has a somewhat runny nose and is sneezing. Can you please help?

A: As you can imagine, it is very difficult to make a diagnosis of this lump based just on your description, but Iím wondering if your cat might have an oral eosinophilic plaque. A condition in cats called the eosinophilic granuloma complex (EGC) is a collection of skin disorders in cats that are often grouped together, because they have the same basic underlying characteristic: infiltration of the skin by eosinophils, a type of inflammatory blood cell  commonly associated with allergic or parasitic diseases.

The cause of EGC is not known, however, an underlying allergy such as flea allergy, atopy (allergy to inhaled environmental allergens) or food allergy has long been suspected. A genetic predisposition to EGC has also been postulated. In some cases, EGC are triggered by an allergic response to mosquito bites. Most of the time, the underlying allergen is never discovered. Any age cat may be affected, but it is most common in young to middle aged cats. In some cats, more than one type of eosinophilic skin disease can occur at the same time. Feline EGC manifests itself in three ways: the indolent ulcer; the eosinophilic plaque; and the eosinophilic granuloma.

Eosinophilic plaques can appear anywhere on the skin, but they are most commonly found on the abdomen and the inside thighs. They may be singular or have multiple lesions. They appear raised, red, moist and well-circumscribed. They are very itchy, and cats lick them constantly. Occasioinally, they can appear in mouth, sometimes on the tongue, sometimes on the roof of the mouth  or in the back of the throat. They will often look pinkish, and have white spots  on them, similar to what you describe.  If your vet hasnít performed a complete blood count, make sure he does.  If there is an increased number of eosinophils in the bloodstream, it strongly supports the diagnosis.  If the eosinophil numbers are normal, it doesnít mean that the lumps are not eosinophilic plaques, however. 

Oral things in cats have the potential to be very bad.  I agree with your vet that they should be surgically biopsied.  If these are eosinophilic plaques, they are treatable.  If it is lymphoma, a type of cancer, it too is treatable.  If it is squamous cell carcinoma or some other type of cancer, it probably is not treatable, given the  location.  The sooner you obtain an answer, the sooner an appropriate treatment  can be administered.

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