Feline Eosinophilic Granuloma

Also known as: Rodent ulcer — Eosinophilic ulcer — Eosinophilic plaques — Eosinophilic granuloma

Introduction

Feline eosinophilic granuloma complex includes three types of lesions:

1. Eosinophilic or rodent ulcers which present as a well circumscribed, erythematous ulcer on the lip or oral mucosa of middle-aged cats
2. Eosinophilic plaques which present as raised erythematous lesions on the skin of the medial thighs and abdomen
3. Eosinophilic or linear granuloma which present on the posterior aspect of the rear legs of young cats and also found on the tongue, hard palate and oral mucosa.

Eosinophilic granulomas of the oral cavity appear as yellow/pink raised linear lesions. They can also occur on the soft palate, or the base of the tongue. Cats with eosinophilic lesions of the mouth often have concurrent skin lesions.

The cause of feline eosinophilic granuloma is unknown but it has been associated with food and insect bite allergies (hypersensitivity), atopy, immunosuppression, bacterial and viral infections.

Signalment

More commonly found in young cats (2-6 years) and also more common in females than males. It can also occur in dogs, particularly Siberian Huskies.

Clinical Signs

Depending on site of lesion can include dysphagia, halitosis and anorexia. Eosinophilic plaque lesions are intensely pruritic.

Diagnosis

An ulcerated mass may be found at the base of the tongue or on the hard palate, the glossopalatine arches or anywhere else in the mouth as described above. On laboratory tests, a peripheral blood eosinophilia may be present, especially for eosinophilic plaques.

Impression smears: Eosinophilic plaques exfoliate easily and eosinophils predominate the sample.

A deep biopsy specimen of the mass is required for a definitive diagnosis.

Pathology

Grossly, there are raised plaques, erythematous, pruritic, erosed or ulcerated areas.

Microscopically, acanthosis, spongiosis, erosions or ulceration, predominantly eosinophilic dermatitis, possibly areas of collagen degeneration can all be found.

Histology reveals:

Eosinophilic ulcers: show hyperplastic, ulcerated, superficial perivascular to interstitial dermatitis. Fibrosis may also be present.

Eosinophilic plaques: appear as superficial hyperplasia, deep perivascular dermatitis with eosinophilia. Diffuse spongiosis of the outer root sheaths of hair follicles may also be noted.

Eosinophilic granulomas: reveal nodular to diffuse granulomatous dermatitis with flame figures. Eosinophils and multinucleated histiocytic giant cells are commonly found.

Treatment

Initial medical treatment is to control any ectoparasites. Secondly a diet trial and intradermal allergy testing may be carried out to rule out food allergy and atopy. If there is evidence of a bacterial infection antibiotics are necessary.

If the patient is refractory to the above Corticosteroid should be administered. Treatment should be tapered gradually once a response is seen then discontinued once signs have completely disappeared.

Chlorambucil may also be useful in resistant cases.

Surgical excision is required for large lesions that interfere with breathing or swallowing.

Prognosis

Good if the allergy is identified and addressed. Otherwise the lesion can recur and lifelong steroid treatment may be necessary.

Feline Eosinophilic Granuloma Learning Resources
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References

Tutt, C., Deeprose, J. and Crossley, D. (2007) BSAVA Manual of Canine and Feline Dentistry(3rd Edition) BSAVA

Nelson, R.W. and Couto, C.G. (2009) Small Animal Internal Medicine (Fourth Edition) Mosby Elsevier.

Norsworthy, G. (2010) The Feline Patient John Wiley and Sons

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