CASE REPORTS 6 1 9

Fig. 1 - Transverse scan inferior to inguinal ligament shows fundus of hernial sac (solid arrow) medial to femoral vein (open curved arrow).

Fig. 2 - Transverse scan at level of inguinal ligament shows neck of hernial sac (solid arrow) medial to femoral vein (open curved arrow) and femoral artery (solid curved arrow).

exploratory laparotomy in an elderly patient who was a poor operative risk. The US appearance of the small bowel within the hernia was of a well-defined wall around echogenic fluid and the peristaltic movement seen within it was a useful additional observation. Although hernias usually contain bowel, other abdominal or pelvic structures, most com- monly omentum, may enter the hernial sac. In such a case US diagnosis would be more difficult.

This case demonstrates the value of US in the investiga- tion of atypical groin lumps particularly in the presence of intestinal obstruction.

REFERENCES

1 Mann CV, Russell RCG (eds). Bailey and Love's Short Practice of Surgery, 21st edn. London: Chapman and Hall, 1992:1288-1289.

2 Corder AP. The diagnosis of femoral hernia. Postgraduate Medical Journal 1992;68:26-28.

3 Hjaltason E. Incarcerated hernia. Acta Chirugica Scandinavica 1981 ; 147:263-267.

4 Hayes SD, Brittenden J. Strangulated femoral hernia: the persisting clinical trap. Postgraduate Medical Journal 1991 ;67:57 59.

5 Roehl J, Schneider B, Sieberth HG. Femoralhernie: Diagnose dutch B- Bild-, Duplex- und farbkodier~e Dopplersonographie. Ultraschall in der Medizin 1995; 16:145 - 147.

6 Bergenfeldt M, Ekberg O, Kesek P, Lasson A. Femoral hernia: clinical significance of radiologic diagnosis. European Journal of Radiology 1990;10:177-180.

Clinical Radiology (1998) 53, 619-622

Case Report: Meningioma Presenting as an Aural Polyp

E. HUIN and K. P. TAN

Department of Diagnostic, Singapore General Hospital, Singapore

Intracranial meningiomas can extend extracranially, espe- cially if the temporal bone is invaded. The commonest pathway in the temporal bone is through the jugular and lacerate foramina into the parapharyngeal (cervical) space [1]. Once the tumour invades a venous sinus, it can invade the middle ear cavity, through the hypotympanum, via the jugular fossa. Subsequent lateral extension into the external auditory canal and presention as an aural polyp is

Correspondence to: Dr E. Huin, Radiologist, Department of Diagnostic Radiology, Singapore General Hospital, Outram Road, Singapore 0316.

exceedingly rare. We report such a case of a patient pre- senting with ear discharge due to an aural polyp which had extended from a large underlying intracranial meningioma.

CASE REPORT

A 45-year-old Chinese woman presented to an otorhinolaryngologist complaining of tinnitus and decreased hearing on the fight for a few months. She had right ear discharge and blocked sensation of the right ear. An aural polyp arising from the floor of the external auditory meatus was detected. No neurological signs, posterior nasal space or neck masses

�9 1998 The Royal College of Radiologists, Clinical Radiology, 53, 619 622.

6 2 0 CL~CAL RADIOLOGY

were detected. Polypectomy was done and meningioma was proven on histology. Patient absconded follow-up and was recalled for further investigations and treatment.

Magnetic resonance imaging (MRI) showed a large right cerebellopon- tine meningioma, with intense enhancement extending into the sigmoid sinus and jugular bulb (Fig. la). A narrow connection from the bulb with the hypotympanum allowed tumour extension into the middle ear cavity, epitympanum and mastoid antrum. Lateral invasion into the medial external auditory canal was shown (Fig. la,b). Invasion into the petrous apex and through the petrooccipital fissure into the upper cervical (para-pharyngeal) region was well demonstrated (Fig. 2). Tumour also extended into the internal auditory meatus. Mild vasogenic oedema was present in the

adjacent cerebellar hemisphere. Compression on the brainstem produced hydrocephalus of the lateral and third ventricles.

Computed tomography (CT) showed the bone changes to advantage (Fig. 3). The medial 1.5 cm of the bony external auditory canal showed fusiform expansion. There was mild sclerosis of the petrous bone, mild erosion of the petrooccipital suture, and possibly of the petrous apex as well. The right jugular fossa was larger but there is wide normal asymmetry here.

Pre-operative angiography showed nonvisualization of the right sigmoid sinus and enlarged occipital arterial feeders (Fig. 4a). The latter were embolized (Fig. 4b,c). At operation, the large solid, fairly vascular cerebellopontine turnout had displaced the right cranial nerve V anteriorly,

(a) Fig. 2 - Petrous apex tumour invasion (arrow) above the cervical soft tissue mass, and petrooccipital extension (large arrowhead), are well shown on enhanced coronal MR scan. The jugular fossa (big white arrow) is turnout filled. Internal auditory meatus extension (small white arrow) and mastoid antrum tumour (small arrowhead) are present.

(b)

Fig. 1 - Post gadolinium-DTPA axial (a) and coronal (b) MRI shows large cerebellopontine meningioma with sigmoid sinus and jugular bulb exten- sion (arrow). Note extension superiorly into the middle ear cavity via the hypotympanum (small white arrow), and then laterally into the external meatus (large white arrow) through the tympanic membrane. Note petrous apical turnout replacement adjacent to the carotid canal and the large soft tissue mass at the right side of the neck (arrowhead).

Fig. 3 - The aural polyp has caused fusiform expansion of the right external auditory canal (arrow) on axial CT. Note the normal larger right jugular fossa (thick arrow), subtle right petrous apical irregularity (short thick arrow) and irregular petrooccipital sutural widening (open arrow), from tumour invasion. Right mastoid air cells are opacified.

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CASE REPORTS 621

(a) (c)

(b)

cranial nerves VII and VIII anterosuperiorly, and invaded around the cranial nerves IX to XI as well as the superficial portion of the cerebellum. Tumour around the porus and within the jugular foramen was easily removed. Preservation of the cranial nerves V to XI allowed partial tumour resection, including the superficially invaded portion of the cerebellum. Tumour within the middle ear and mastoid antrum was removed concomitantly. Meningothefiomatous meningioma was found on histology.

DISCUSSION

Meningiomas are the second largest group of brain tumours after gliomas. They account for 13% to 18% of all primary intracranial neoplasms. The majority occur in the supratentorial compartment, with only 8% to 9% occur- ring in the posterior fossa. Twenty per cent of intracranial meningiomas eventually develop an extracranial extension, in order of decreasing frequency, to the orbit, the external

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Fig. 4 - (a) Cerebral angiography shows unopacified right sigmoid sinus and internal jugular vein (arrow) whilst a large vein of Trolard anastomoses with the sphenoparietal plexus (arrowheads). (b) The meningioma is supplied by a large occipital artery, which shows devascularization after embolization (c).

table of the calvaria, the nasal cavity and paranasal sinuses, and the parapharyngeal (cervical) space. Once a menin- gioma has gained access to the temporal bone, its tendency to extend beyond the confinements of the skull increases to 43%, most frequently through the jugular and lacerate foramina into the parapharyngeal space [1].

Meningiomas of the jugular foramen manifest the same signs and symptoms as glomus jugulare tumours. They arise from arachnoid cells lining the jugular bulb, grow slowly and infiltrate the temporal bone and posterior fossa. These lesions are more clinically treacherous than glomus tumours, as these infiltrate adjacent bone and nerve tissue, and therefore require a wide margin of resection [2]. Meningiomas arising in the cerebellopontine angle can infiltrate into the jugular bulb, as in our case. Venous sinus invasion allows both superior and inferior extension of tumour. Inferiorly the upper portion of the neck can be reached. Superiorly the hypotympanum is invaded and

622 CLINICAL RADIOLOGY

subsequently the middle ear cavity proper, epitympanum and mastoid antrum [1,3,4]. MRI reveals the vascular and soft tissue structures to best advantage.

Parapharyngeal (cervical) extension occurs in gross extension of intracranial tumours [1,4]. Meningiomas extending to the neck are unique because of their tendency toward extracranial expansion, higher incidence of local recurrence, multicentric growth and frequent combination with other neoplasms of the central nervous system, e.g. in von Recklinghausen's disease [1]. In our patient, cervical extension extended from jugular foramen invasion as well as via the petrooccipital fissure. Intracranial tumours that extend to the middle ear and external meatus are uncom- mon. A rare case report of another intracranial tumour that extended to the middle ear and external meatus is a vestibular schwannoma [5]. Meningiomas extending to the external auditory canal are exceedingly rare. An earlier case of meningioma presenting as an aural polyp was reported in 1992 [6]. Our patient is believed to be the second reported case. The operative approach to such aural polyps would involve both craniotomy and translabyrinthine surgery, therefore differing from the operative approach to the majority of aural polyps which arise de novo. The latter include benign lesions such as exostosis, osteoma, benign ceruminoma, sebaceous cyst and keloid. External auditory tumours that can erode bone include chondroblastoma, giant cell tumour, histiocytosis, adenoid cystic and ceruminous adenocarcinoma, basal cell and squamous cell carcinomas, and less common malignancies [7].

The initial presentation of our patient was that of tinnitus and blocked right ear sensation, due to a sizeable aural polyp arising from the floor of the external auditory canal and middle ear cavity. The presentation was unusual

in that there were no demonstrable neurological signs clinically, despite the large size of the intracranial tumour and mass effect. MRI depicted the route of spread into the jugular bulb better than CT. The lesion extended through the petrous bone into the hypotympa- num, and then into the middle ear cavity and mastoid antrum.

The differential diagnoses of external auditory canal lesions should therefore be expanded to include meningioma, as it may be the only or initial presentation of an intracranlal posterior fossa tumour.

REFERENCES

1 Nager GT, Heroy J, Hoeplinger M. Meningiomas invading the temporal bone with extension to the neck. American Journal of Otolaryngology 1983;4:297-324.

2 Molony TB, Brackmann DE, Lo WW. Meningiomas of the jugular foramen. Otolaryngology Head and Neck Surgery 1992;106: 128-136.

3 Lo WWM. The temporal bone: tumors of the temporal bone and the cerebellopontine angle. In: Som PM, Bergeron RT, eds. Head and Neck Imaging, 2nd edn. Missouri: Mosby Year Book, 1991:1069-1082.

4 Schmidt D, Mackay B, Luna MA et al. Aggressive meningioma with jugular vein extension: case report with ultrastructural observation. Archives of Otolaryngology 1981; 107:635-637.

5 Woolford TJ, Birzgalis AR, Ramsden RT. An extensive vestibular schwannoma with both intracranial spread and lateral extension to the external auditory canal. Journal of Laryngology and Otology 1994;108:149-151.

6 Brugler G. Tumors presenting as aural polyps: a report of four cases. Pathology 1992;24:315-319.

7 Lo WWM. The temporal bone. Tumors of the temporal bone and cerebellopontine angle. In: Som PM, Bergeron RT, eds. Head and Neck Imaging, 2nd edn. Missouri: Mosby Year Book, 1991:1094- 1096.

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