Auricular chondropathy in aging rats.

An external ear lesion designated as auricular chondropathy in aging Crl:CD rats was reported. One hundred eighty (180) of 4,876 rats (3.7%) had ear deformity. Grossly, the ears were thickened, nodular, or disfigured. Both ears were affected in most rats. The lesions primarily involved the cartilaginous plate and were associated with two processes--chondrolysis and granulomatous inflammation. The detailed morphogenesis of the lesions is described, but the etiology of the lesions is unknown. Auricular chondropathy in rats and relapsing polychondritis in man are compared.