Experimental cholesteatomas arising from autologous free skin grafting in the middle ear cavity.

An autologous free skin graft taken from the upper or the lower external ear canal or the auricle was implanted in the otic bulla of 28 guinea pigs. An epidermal cyst simulating middle ear cholesteatoma was successfully produced in 25 (89.3%) animals 8 weeks after grafting. Using this model, the histological reaction of middle ear granulation tissue to the debris was studied. Cysts originated from the auricular skin showed the strongest activity with regard to growth rate, amount of debris produced, and inflammatory reaction to the exposed debris. We conclude that the exposed debris plays an important role in chronic granulomatous inflammation in association with cholesteatoma.