Eosinophilic Granuloma Complex in Cats

Eosinophilic granuloma complex is a group of skin and mouth conditions in cats that share a common underlying pattern: clusters of immune cells called eosinophils gather in affected tissue, creating characteristic lesions. The name describes what is seen under the microscope rather than a single disease, and the exact trigger often remains unclear even after investigation. Owners typically notice one of several distinct patterns: ulcers on the upper lip, raised plaques on the belly or inner thighs, or thickened areas in the mouth. Some cats show little discomfort, while others may lick or scratch persistently. The appearance can be striking, and it is common to wonder whether the lesion is infectious, cancerous, or self-inflicted. This page explores what these patterns can look like when they first appear, what is understood about the immune processes underneath, how the condition is investigated and distinguished from other causes, and the range of approaches used to manage it. The course varies widely between individuals, and response to treatment can help clarify what is driving the reaction in a particular cat.