Feline eosinophilic granuloma complex is a group of common diseases in cats that can present three clinical forms: indolent ulcer, eosinophilic plaque and eosinophilic granuloma. They are made up of a similar histology, an inflammation with abundant eosinophils (cells that intervene in the immune response to infections, allergic reactions or inflammatory processes, among others), with the indolent ulcer being the one that presents the least, as well as neither itching nor pain. Degeneration of collagen tissue is seen in the case of eosinophilic granuloma, and the eosinophilic plaque is very itchy in affected cats. The definitive diagnosis that will differentiate it from other diseases with similar lesions will be histopathology, based on a biopsy, although cytology can also be very useful for the same.
What is feline eosinophilic granuloma complex?
Eosinophilic granuloma complex comprises a heterogeneous group of cutaneous, mucocutaneous and oral cavity lesions, which are patterns of a skin reaction resulting from underlying hypersensitivities. Histopathologically and clinically, they are grouped into three forms: eosinophilic plaque, eosinophilic granuloma and indolent ulcer These clinical forms can occur in the same cat all at at once or successively.
In all forms, the predominant eosinophilic component is common in the tissues, due to a chemotactic or attraction action carried out by certain agents, including microorganisms, parasites such as fleas or hypersensitivity reactions such as atopic dermatitis, adverse reaction to food or fleas or mosquitoes. As a consequence, an inflammatory reaction occurs with the permanence of the eosinophils that will cause this reaction to persist, which will lead to the formation of a bulge with eosinophil granules, which release the main or cationic basic protein and leads, in some cases, to a collagen necrosis.
Symptoms of eosinophilic granuloma complex in cats
As we say, it mainly comes in three forms, so we will detail the symptoms that a cat can present in each of them:
Eosinophilic plaque symptoms
It is the most pruritic clinical form (it causes a lot of itching), which especially affects cats between 2 and 6 years of age and is limited to the ventral areas such as the abdomen, the inner face of the thigh or groin area and may be accompanied by enlargement of the lymph nodes It is usually more frequent in spring due to sensitivity to fleas or environmental allergens, as well as well as by food allergens.
The lesions are oval or circular in shape, devoid of hair and with circumscribed borders, simple or multifocal, highly inflammatory, itchy, reddened and they form plaques with a lot of exudation that causes the cat not to stop licking.
Eosinophilic granuloma symptoms
Also called linear or collagenolytic granuloma, where the affected area suffers collagen damage. The lesions do not appear to be pruritic or predisposed in any race, age, or sex. They are usually found as raised alopecic lines of lesions, red and grainy in appearance on the posterior thighs, in a pattern associated with cat grooming.
Other locations are the chin, lower lip, oral cavity and even the nose, muzzle and the joints of the pads and skin of the fingers. The nodules of the oral cavity are generally found on the tongue or soft palate and whitish foci can sometimes be observed that correspond to the areas where collagen damage has occurred and do not usually interfere with chewing and apprehension.
It is usually due to hypersensitivity to fleas, allergy, atopic dermatitis or food allergy.
Indolent Ulcer Symptoms
Also called eosinophilic ulcer and mainly affects females between 5 and 6 years of age, limited to the mucocutaneous junction of the upper lip They are well-defined, shiny, alopecic lesions that thicken and increase in color (erythema), giving them a "cooked meat" appearance and even ulceration. However, despite their unpleasant appearance, they do not cause pain or itching.
May start with a small lump that ulcerates and spreads to the nose, especially if the cat repeatedly licks itself, causing more damage than injury. There is some evidence that it may be due to an allergy to fleas or other allergens, but in many cases it is impossible to know the cause and it is classified as "idiopathic".
Diagnosis of feline eosinophilic granuloma complex
Recognizing the lesions of the eosinophilic granuloma complex in cats do not usually have many complications and with a detailed anamnesis and clinical history, the possible allergic cause can be considered. A differential diagnosis should always be made with other skin diseases or that can give lesions similar to indolent ulcers or ulcers and granulomas of the feline oral cavity, such as:
- Mastocytoma.
- Squamous cell carcinoma.
- Herpesvirus.
- Calicivirus.
- Cryptococcosis.
- Pemphigus vulgaris.
- Lymphosarcoma.
- Fibrosarcoma.
- Plasmacocyte stomatitis.
Bacterial cultures and susceptibility testing may be performed to provide more information on a possible bacterial origin and the appropriate antibiotic for treatment. On the other hand, skin scrapings allow a parasitic origin to be ruled out. Also, in the blood test, especially in the eosinophilic granuloma or plaque, there may be eosinophilia (increased eosinophil count).
The definitive diagnosis will be given by cytology or biopsy, so samples of the lesion must be taken for analysis and detection of changes associated with feline eosinophilic granuloma complex lesions:
- In the cytology of lesions categorized as plaque or eosinophilic granuloma, macrophages and eosinophils will be evident, while the indolent ulcer will not so much predominance of eosinophils, but abundant macrophages and bacteria.
- In the skin biopsy, histopathological examination shows, in the case of eosinophilic granuloma, granulomatous inflammation with focal areas of collagen degeneration surrounded by abundant eosinophils, followed by a smaller number of macrophages and mast cells and palisade multinucleated giant cells. In the case of eosinophilic plaque, spongiotic inflammation is observed in the dermis and a predominance of eosinophils that can extend to the subcutaneous tissue; mast cells, macrophages, and lymphocytes may also be present, but in smaller numbers. In the indolent ulcer, diffuse infiltrates of eosinophils will be observed together with neutrophils, macrophages and mast cells, but on many occasions biopsies are performed in the chronic phase and lymphocytes, plasma cells, neutrophils (more the greater the degree of ulceration), would be seen. macrophages and fibrosis. Histopathological analysis is very useful to rule out other diseases such as tumors or immune-mediated diseases, since the treatment and prognosis would be very different.
Feline eosinophilic granuloma complex treatment
The main thing is to identify and eliminate the cause of hypersensitivity or allergy. A flea treatment and elimination diet should be applied in order to find a food intolerance. However, the latter is a much longer and more complicated process, so these injuries are usually started with the following treatments:
- Glucocorticoids to reduce the number of eosinophils and improve lesions. They are considered the treatment of choice for the three forms of feline eosinophilic granuloma complex. Prednisolone 2-4 mg/kg/day orally can be used initially, tapering to 2 mg/kg every 48 hours until lesions resolve. Doses of 4 to 5 mg/kg of methylprednilsolone acetate subcutaneously or intramuscularly every 2 weeks, with a maximum of 3 applications, or dexamethasone at doses of 0.1-0.2 mg/kg every 24 hours can also be used. initially and 0.05-0.1 mg/kg every 72 hours for maintenance orally or added to food. If the corticosteroids are suspended before the lesions have fully healed, they will reappear.
- Immunosupressors to immunomodulate the immune system through immunosuppression. Cyclophosphamide can be used at a dose of 1 mg/kg orally, 4 weekly doses up to 4-6 weeks and the response in the reduction of lesions may take between 1-4 weeks. Cyclosporine is also frequently used to reduce eosinophils with doses of 7 mg/kg every 24 hours for 4 weeks and, if a good response is seen, it can be reduced every other day and then twice a week. Chlorambucil is the drug of choice when cats are refractory to glucocorticoids, and can be administered together with these at doses of 0.1-0.2 mg/kg/day or every 2 days up to 4-8 weeks, but once a favorable response is determined in the lesions, the dose of glucocorticoids should be reduced first, followed by that of chlorambucil, as long as they continue to regress. What is sought with these treatments is to find the lowest possible dose that allows the remission of the lesions.
- Antihistamines when the cat has atopy, hypersensitivity to flea bites or idiopathic aetiology. Chlorphenamine maleate and hydroxyzine hydrochloride can be used for 15 consecutive days. However, if the cause is unknown or the process is very chronic or uncontrollable, corticosteroids will always be more useful.
- Antibiotics such as amoxicillin-clavulanic acid at 12.5 mg/kg/every 12 hours or trimethoprim-sulfamethoxazole at 30 mg/kg / every 12 hours, but the best is the antibiotic determined by the antibiogram. The minimum duration of antibiotic treatment is two weeks, and it lasts for at least 10 days after healing. They are especially effective in cases of indolent ulcers, since their origin is mainly associated with bacteria.
- Fatty acids on food as a supplement in chronic cases for 4-6 weeks. They are more effective for eosinophilic granuloma.
- Surgery, cryosurgery or radiation for certain types of injuries that require it because they are very chronic, refractory or difficult, especially in cases of indolent ulcer.
Blood, biochemical, and urinalysis with culture are required in cats treated with glucocorticoids to monitor for bone marrow suppression and to monitor for complications such as development of kidney disease, upper tract infection urinary or diabetes.
You should never self-medicate your cat because, as you can see, it is essential to make a diagnosis to establish treatment.
Forecast
Cats with eosinophilic granuloma complex usually have a good prognosis with appropriate treatment and check-ups, with a higher rate of recurrence of the disease cats that are refractory to glucocorticoids, requiring more aggressive treatment. If the triggering cause can be determined and avoided, the lesions should disappear forever.
So, in the event of any dermatological lesion that we have mentioned in our cat (ulcers on the upper lip, mouth lesions, plaques on the ventral areas or lesions on the back of the thighs…), whether they itch or not, a visit to the vet is essential, in order to find this problem in time and be able to treat it.
