 |  |  |  |  |  |  |
| | |||||||
| Discussion |
Case Report: A 40-year-old lady presented with complaints of left sided earache, decreased hearing on the left and pulsatile tinnitus since four months. She had no history of ear discharge. Except for mild conductive hearing loss, her physical and ENT examinations were normal.
HRCT of the temporal bone:
A soft tissue mass was seen in relation to inferior or jugular wall of the middle ear cavity. This mass extended into the middle ear cavity by eroding through the wall of the jugular foramen. There was also erosion of the inferior aspect of the internal auditory canal and carotid canal. On post contrast images, the mass showed moderate enhancement. |
 |
Fig: 1 |
Fig: 2 |
MRI of temporal bone:
Plain and contrast enhanced MRI of the lesion skull base showed the soft tissue mass extending inferiorly into the ipsilateral para-paryngeal space. On T1 WI, the mass was hypointense. On T2WI it showed multiple flow voids. On post contrast images, there was enhancement of the soft tissue mass.
 |
 |
Fig: 3 |
Fig. 4 |
 |
|
Fig. 5 |
|
Based on these classical radiological findings a diagnosis of a glomus jugulare tumor was made.
DISCUSSION:
Glomus jugulare tumors are rare, slow-growing, hypervascular tumors that arise within the jugular foramen of the temporal bone
INCIDENCE:
Glomus tumors occur with an estimated annual incidence of 1 case per 1.3 million people.
Although rare, glomus tumors are the most common tumor of the middle ear and are second to vestibular shwannoma as the most common tumor of the temporal bone.
The female-to-male ratio is 3-6:1. Glomus jugulare tumors have also been noted to be more common on the left side, especially in females.
Most tumors occur in patients aged 40-70 years, but cases have been reported in patients as young as six months and as old as 88 years.
Although most paragangliomas are sporadic, they can be familial with autosomal dominant inheritance and incomplete penetrance
PATHOPHYSIOLOGY:
Glomus bodies or paraganglia are small collections of paraganglionic tissue. They are derived from embryonic neuroepithelium in close association with the autonomic nervous system and are found in the region of the jugular bulb. Glomus jugulare tumors originate from the chief cells of the paraganglia.
CLASSIFICATION:
The Glasscock-Jackson and Fisch classifications of glomus tumors are widely used. The Fisch classification of glomus tumors is based on extension of the tumor to surrounding anatomic structures and is closely related to mortality and morbidity.
Type A tumor - Tumor limited to the middle ear cleft (glomus tympanicum)
Type B tumor - Tumor limited to the tympanomastoid area with no infralabyrinthine compartment involvement
Type C tumor - Tumor involving the infralabyrinthine compartment of the temporal bone and extending into the petrous apex
Type C1 tumor - Tumor with limited involvement of the vertical portion of the carotid canal
Type C2 tumor - Tumor invading the vertical portion of the carotid canal
Type C3 tumor - Tumor invasion of the horizontal portion of the carotid canal
Type D1 tumor - Tumor with an intracranial extension less than 2 cm in diameter
Type D2 tumor - Tumor with an intracranial extension greater than 2 cm in diameter
CLINICAL FEATURES:
Patients present with pulsatile tinnitus, conductive hearing loss, retro tympanic mass, and cranial nerve deficits. Most tumors are slow growing but locally invasive. They may have earache, vertigo and sensory- neural hearing loss. Up to 4% of the tumors are functional and produce clinically significant levels of catecholamines, norepinephrine, or dopamine with symptoms mimicking a pheochromocytoma.
RADILOGIC EXAMINATION
Plain films may ay show enlargement of the lateral jugular foramen and fossa or erosion of adjacent bone.
HRCT features:
On high-resolution CT scans of the temporal bones, expansion and erosion of the jugular foramen characterize the glomus jugulare tumor. Perhaps the earliest abnormality detectable on cross-sectional images of a glomus jugulare tumor is erosion of the lateral and anterior walls of the osseous jugular fossa on a thin-sections bone algorithm.
Progressive growth of the tumor produces the typical moth-eaten pattern of erosion of the jugular foramen and destruction of the surrounding bony labyrinth including the caroticojugular spine. The tumor spreads along the paths of least resistance and is initially directed superiorly owing to the intrinsic weakness of this part of the jugular fossa.
Subsequently, the hypotympanum, mesotympanum, and the sinus tympani are invaded. Ossicular chain destruction is common. Inferior spread of the tumor produces infiltration of the IJV and intratemporal fossa. As the tumor spreads laterally, it may destroy the facial nerve canal and infiltrate the facial nerve. On post contrast images the mass shows intense enhancement.
MRI features:
Paragangliomas typically exhibit low signal intensity T1WI and high signal intensity with T2WI. Multiple serpentine and punctate areas of signal void characterize the typical Paraganglioma with all MR sequences; these areas are variably distributed throughout the mass and are believed to represent flow voids in the larger intratumoral vessels.
The classic ‘salt-and-pepper appearance’ was originally described by Olsen et al from appearances on long TR/long TE images. The "pepper" component represents the multiple areas of signal void interspersed with the "salt" component seen as hyperintense foci (due to slow flow or hemorrhage on both short TR and long TR images. This feature is limited to paragangliomas that are greater than 1 cm in diameter and is not considered diagnostic.
In addition to providing superior definition of location, extent, and characterization of paragangliomas, MR imaging also better demonstrates tumor involvement of the ICA and IJV compared with that seen with CT.
MR imaging can depict paragangliomas that are smaller than 5 mm, whereas CT demonstrates only lesions greater than 8 mm
Angiography:
It reveals a blush; most often from the ascending pharyngeal artery additionally it may involve the posterior auricular, occipital, maxillary, or internal carotid arteries.
TREATMENT:
Medical therapy: Some cases require no treatment. Often, glomus jugulare tumors are diagnosed within the sixth or seventh decade of life and can be followed by imaging and may not need surgical intervention.
Pre- surgical embolisaion of the tumor can be done.
Radiation therapy and radio-surgery can also be done.