Eosinophilic granuloma is a form of Langerhans cell histiocytosis. It is a condition of both human and veterinary pathology. Feline eosinophilic granuloma complex is synonymous with feline eosinophilic skin diseases. This is considered to be a cutaneous reaction pattern that can be the manifestation of a number of underlying infections, allergies or ectoparasite infestations. It can also be idiopathic, that is have no discoverable underlying trigger. The eosinophilic reaction is common in feline inflammatory disease and the eosinophilic granuloma can be a hereditary reaction pattern in some lines of domestic cats.