Dexamethasone inhibition of the development of dysplastic bony lesions in LP/J mice.

Inbred LP/J mice have been observed to spontaneously develop abnormal bony lesions of the ossicles and otic capsule that progress throughout the life of the animals. This genetically inherited murine disorder produces bony lesions that share some gross and histologic features with bony lesions seen in human tympanosclerosis. Previous studies on LP/J mice have demonstrated evidence of immunologically mediated injury in the progression of the newly forming bony lesions. This study was designed to examine the effects of dexamethasone on the development of the bony lesions in LP/J mice. The purpose was to attempt to elucidate the relationship of the immunologic injury observed in earlier studies and the progression of the dysplastic bony lesions. The results show that LP/J mice treated with dexamethasone developed significantly fewer dysplastic bony lesions compared to the age-matched, saline-treated controls. There was also a statistically significant difference in the quantity and cellularity of the middle ear effusions between the experimental and control animals.