[Cholesteatoma of the petrous bone with major expansion. Apropos of 17 cases].

Cholesteatomas with major extension correspond to lesions invading beyond the classical limits of middle ear affections. Pathogenicity, and clinical and therapeutic aspects of the disorder are discussed in relation to 17 cases where the affection appeared to be secondary to initial otitic lesions. The diagnostic difficulty in patients with open tympanic membranes is the evaluation of the degree of extension of the lesion, while it has to be considered in patients with closed membranes, particularly in the presence of facial paralysis and internal ear deafness. Radiographic examinations, even when of high quality, may fail to detect cholesteatomas with major extension, and these may be a surprising finding on operation. Treatment is uniquely surgical and requires experience in otoneurosurgical techniques. Total excision is essential in order to avoid rare but serious complications of the affection.