Effect of trans-retinoic acid in the inhibition of cholesteatoma in guinea pigs

Middle ear cholesteatoma affected more than 5 million people until the 80's. Many animal models were used, unsuccessfully, to study an alternative therapy to cholesteatoma. AIM: observe the effect of the trans-retinoic acid in the inhibition of middle ear cholesteatomas induced by propylene glycol. STUDY DESIGN: Clinical and Experimental. METHODS: 25 guinea pigs were submitted to the application of a 100% propylene glycol solution in their bulla bilaterally and a solution of trans-retinoic acid was applied locally in the external right ear, while in the left ear saline solution was applied (control ear). The guinea pigs were slaughtered and their temporal bones were prepared for macroscopic and histological analysis. RESULTS: The macroscopic findings had evidenced the presence of cholesteatoma in 25% of the right ears and 85% of the left ears (P=0.0003 *). The histological study had evidenced the presence of cholesteatoma in 30% of right ears and 75% of the left ears (P=0.0104*). CONCLUSION: The local use of the trans-retinoic acid is effective in inhibiting the induced formation of cholesteatomas in guinea pigs.