A Unique Case of Pneumatised Styloid Process with Cholesteatoma

Pneumatisation of styloid process is a very rare finding and has never been reported previously. We present a unique case of a pneumatised styloid process with a cholesteatoma arising within the cavity. We describe the clinical features, associated radiological findings, and management of this lesion. 1. Introduction Styloid process develops from the dorsal part of the second branchial arch (Reichert cartilage) at around fourth week of intrauterine life [1, 2]. Its base becomes embedded in the petromastoid region of the temporal bone thereby making it a part of temporal bone. The pneumatisation of temporal bones starts late in fetal life and continues until the adult life [3]. Pneumatisation process is variable and in cases where there are well pneumatised temporal bones, accessory air cells may occur and communicate with the middle ear mastoid air cells [3, 4]. Therefore theoretically pneumatisation can be seen in some portions of the skull base as well [3]. Extensive pneumatisation of skull base and atlas vertebrae [3] has been described in the literature; however, pneumatisation of the styloid process has not been reported before. We present a unique case of pneumatised styloid process with a cholesteatoma arising within it. 2. Case A 43-year-old female presented to our otolaryngology department with an 11-month history of recurrent, right-sided otalgia and foul-smelling otorrhoea. The condition had been misdiagnosed as recurrent otitis externa. Patient denied any history of hearing impairment, vertigo, tinnitus, facial nerve palsy, or a history of head trauma. Clinical examination revealed squamous debris and purulent material in a grossly eroded floor of bony meatus with the lower half of the tympanic membrane hanging in the breeze. The facial nerve function was normal and there were no other neuro-otologic signs. Examination of contralateral ear and rest of the ENT examination were unremarkable. CT scan of the temporal bone demonstrated an extensively pneumatised styloid process containing a soft tissue mass (Figures 1(a) and 1(b)). Further MRI imaging showed a hyperintense material in the pneumatised right styloid process on T2 weighted imaging (Figure 2(a)), of intermediate signal intensity on fat suppressed T1 weighted imaging (Figure 2(b)) and marked hyperintensity on PROPELLER (periodically rotated overlapping parallel lines with enhanced reconstruction) diffusion weighted imaging (Figure 2(c)). These signal characteristics are typical of cholesteatomas. In addition there was erosion of the hypotympanum. No intracranial involvement was seen.