[5 cases of epidermoid cyst (or primary cholesteatoma) of the petrous pyramid. Clinical, radiologic, pathogenic and therapeutic aspects. Value of nuclear magnetic resonance in the diagnosis and postoperative monitoring].

Five cases of epidermoid cyst (or primary cholesteatoma) of petrous bone are described and the criteria necessary to consider these tumors as truly primary outlined. The most plausible theories appear to be either congenital: embryonic inclusions or, to a lesser degree, acquired: papillary proliferation. Emphasis is placed on facial signs, even minimal, associated with progressive perception or mixed unilateral deafness. Advantages and indications for different surgical approaches are discussed and the value of NMR imaging emphasized, both for diagnosis and postoperative follow up review, especially when a closed technique had been selected.