THE feline eosinophilic granuloma
complex (EGC) is a description
of a group of skin lesions seen
commonly in cats. It is one of the major cutaneous reaction
patterns in the cat and should not
be considered a
diagnosis.
Those lesions
comprising the
complex are:
- Indolent ulcer
(formerly known as “rodent ulcer”); - Eosinophilic plaque;
- Eosinophilic granuloma.
Indolent ulcers occur on the
inner surface of the upper lips.
Eosinophilic plaques often occur on
the ventral abdomen and medial thigh.
Eosinophilic granulomas can be quite
variable in their appearance.
They are often found on the backs
of the thighs in a linear fashion (linear granuloma). Other
sites include the
face, particularly
the pre-auricular
alopecia area, the chin (fat chin
syndrome), the pads and the oral cavity.
EGC lesions may appear as solitary
lesions or sometimes two or three
different lesions of the complex occur
on the same cat.
EGC lesions are most commonly the
result of an underlying hypersensitivity
to fleas (the most important cause),
food and mosquitoes. Bacteria may be
involved particularly as a secondary
component. Viral causes are rare and
some cases are idiopathic.
When chin lesions appear they
are often the only lesion and may
appear overnight prompting an early
presentation to the veterinary clinic.
Fat chin lesions typically consist of
swelling, oedema, erythema and hair
loss. The lesions are
not usually painful or pruritic and are
soft on palpation.
Differential diagnosis
- Bacterial causes – such as feline acne;
- Neoplasia.
Diagnosis
- History and physical examination.
Inspection of the oral cavity is
important as typical eosinophilic
granuloma lesions may occasionally be
found on the soft palate, hard palate or
tongue. - Cytology – impression smear.
Eosinophils are present. Neutrophils
and bacteria may be found in chronic
cases that have become secondarily
infected. - Histopathology. Histopathological findings are characteristic and
include nodular or diffuse granuloma
with eosinophils, histiocytes and
multinucleated giant
cells. Biopsy is not
always necessary
initially and can be
reserved for those
cases not responding
to treatment.
Treatment
- If bacterial
infection is found
on cytological
examination
a course of
antibacterial therapy
is necessary. Amoxicillin/clavulanate
or cephalexin for three weeks usually
suffices. - Fat chin syndrome in the absence
of bacteria usually responds rapidly
to a short course of glucocorticoids. Prednisone at a dose of
1-2mg/kg will reduce the chin size to
normal within a week or so. In order
to maintain this remission attempts
should be made to identify underling
allergens. - A thorough flea eradication
programme is an essential starting
point. - If relapse occurs in spite of
comprehensive flea control, the next step is investigation
of the possible role of
food. This involves a
6-8 week food trial with
a hypoallergenic diet
followed by challenge
if the diet succeeds in
maintaining remission. - Feline atopy is a
default diagnosis
after ruling out other
underlying causes. - In idiopathic cases
alternate low dose
glucocorticoids or cyclosporine (Atopica, Novartis) are
effective long term. Some idiopathic
cases appear intermittently and can
be managed with short courses of
glucocorticoids with minimum risk of
side effects.
