Otic capsule bony lesions in the Palmerston North autoimmune mouse.

Otosclerosis is an otic capsule disorder of unknown etiology. While autoimmunity has been proposed as part of the etiopathogenesis of otosclerosis, no spontaneous autoimmune disease animal model has been identified. In the Palmerston North mouse, a model for systemic lupus erythematosus, sclerotic lesions consistently develop within the modiolus that are correlated with systemic autoimmune disease symptoms. No lesions were seen in 2-month-old mice, which is before autoimmune disease onset at 4 months. Lesions were first seen in mice at 6 to 8 months of age and increased in size and frequency thereafter. By 20 months, all ears examined had the otic capsule lesions, which were primarily perivascular in location and composed of both noncellular and cellular elements. The noncellular material was globular to fibrillar in arrangement and stained positively for calcium. The associated cells appeared to be metabolically active fibroblasts. It is proposed that the Palmerston North mouse may serve as a model to further investigate the role of autoimmunity in otosclerosis and other forms of otic capsule osteogenesis.