HISTIOCYTOSIS-X OF THE PETROUS PYRAMID IN ADULTS - APPEARANCES WITH CT AND MRI

Two cases are reported of histiocytosis X in young adults, both confin ed to the petrous bone. In one case the clinical signs were those of a progressive facial palsy, developing over 3 years; the other case had pulsatile tinnitus with clear otorrhoea and symptoms of vestibular de ficiency. Computed tomography showed extensive bone destruction by a s oft-tissue density process which enhanced strongly after iodinated con trast injection. Magnetic resonance imaging (Tl weighted sequences bef ore and after intravenous gadolinium injection) confirmed the presence of a mass lesion in the petrous bone with contrast medium uptake whic h showed cystic areas within it: it also showed the absence of extensi on through the dura mater by the intracranial component which remained extradural. It confirmed the patency of arteries and veins, so enabli ng a differentiation to be made between histiocytosis X and advanced g lomus tumours.