A granuloma is a solid grouping of inflammatory cells coming together in a lump or solid structure. Eosinophilic refers to eosinophil which is a type of white blood cell that is commonly associated with allergic responses or with parasitism. They are part of the immune system and are on patrol for biochemical signals from tissue telling them that a parasite has invaded. In response, eosinophils release chemicals to attack the parasite. Unfortunately, they can be tricked into thinking that some sort of benign materials (pollens, dust, etc.) are attempting invasion. In this instance (allergy), they release their inflammatory chemicals inappropriately, creating the sensations of itching, swelling, redness and other symptoms of allergy.
In dogs, the eosinophilic granuloma complex is a sometimes confusing term for three distinct syndromes that cause inflammation and irritation of the skin.
It should be noted that in dogs, eosinophilic granulomas are rare and are not part of the eosinophilic granuloma complex. Eosipphilic do occur but are not part of granuloma complex which is restricted to cats.
Eosinophilic plaque is circumscribed, raised, round-to-oval lesions that frequently are ulcerated and usually appear on the abdomen or thighs. The lesions contain a type of white blood cell called an eosinophil and usually appear between the ages of two and six years. Genetically initiated eosinophilic granuloma will be seen in dogs that are younger than two years.
Allergic disorders usually develop after a dog has reached the age of two, with allergy related eosinophilic granuloma becoming apparent before the dog has reached three years of age.
Lesions of more than one syndrome may occur simultaneously. In dogs, you may notice one or more ulcerated masses that are thick with a flat top, and that appear dark or orange in color.
Circumscribed, raised, round to oval lesions frequently ulcerated
Moist or glistening plaques (may have enlarged lymph nodes)
Near the chest
Inner thigh area
Near the anus
Under front legs
Back of the thigh
Multiple lesions coming together
Coarse, cobblestone pattern
White or yellow
Lip or chin swelling (edema)
Ulcers of the mouth
Found on upper lip
Within the oral cavity, ulcers on gums
Slightly raised margins
May transform into a more malignant cancerous form (carcinoma)