Eosinophilic complexes or granulomas are always a response to some type of allergen irritating the cats immune system. This complex is seen usually in 3 distinct forms.
1. A rodent ulcer (as it is called) or small inflamed patch of skin under the chin or on the upper or lower lips of the cats. Years ago, a huge cause of these ulcers was the irritation of red plastic food and water bowls containing a red plastic dye.
2. Small eosinophilic granulomas (scar tissue) that is usually one inch in diameter or less and are round. These may be found anywhere on the skin or inside the mouth.
3. The more severe eosinophilic plaques are almost always seen on the inner groin or abdomen of the cat causing intense misery and irritation to the animal. These plaques are about one inch in diameter and they are raised (thickened) and extend above the skin surface. The outer surface of the plaque is intensely inflamed. Many of these plaques will coalesce together and form one huge massive plaque on the cats abdomen.