The Effect of Cyclophosphamide on Development of Experimental Cholesteatoma

Recent work has shown that middle ear application of propylene glycol in chinchillas produces an inflammatory reaction resulting in cholesteatoma formation in 50% to 70% of animals. This study was done to determine if cyclophosphamide, an immune suppressor and anti-inflammatory agent, is capable of inhibiting cholesteatoma development in the animal model. Ten adult chinchillas received systemic cyclophosphamide (20 mg/kg per day) for 14 days. On days 5, 8, and 11 of that period, the animals also received bilateral middle ear applications of 60% propylene glycol (0.2 mL per ear). Four weeks after the first propylene glycol application, the animals were killed for histologic evaluation. Eight of the 10 animals survived the full 4-week study period, providing 16 temporal bones for evaluation. It was found that cyclophosphamide reduced the leukocyte counts; however, middle ear inflammation appeared unaffected. Cholesteatoma occurred in eight (50%) of the 16 ears studied, and histologic findings were essentially identical to those previously seen in animals given propylene glycol alone. Under the conditions of this study, cyclophosphamide had no effect on cholesteatoma development in the animal model.