|Year : 2013 | Volume
| Issue : 2 | Page : 68-71
Paraganglioma of left cerebellopontine angle
Saurabh Arora1, Shrijeet Chakraborti1, Ramdas Naik1, Chandra Kumar Ballal2
1 Department of Pathology, Kasturba Medical College, Mangalore, Karnataka, India
2 Department of Neurosurgery, Kasturba Medical College, Mangalore, Karnataka, India
|Date of Web Publication||15-Jun-2013|
Department of Pathology, Kasturba Medical College, Lighthouse Hill Road, Mangalore 575 001, Karnataka
Source of Support: None, Conflict of Interest: None
Paraganglioma is a rare tumor of the cerebellopontine angle. We report a case of a 55-year-old female presented with otalgia and decreased hearing in the left ear, hoarseness of voice, difficulty in swallowing, nasal regurgitation, and tinnitus. The tumor was excised by left retromastoid and posterior fossa craniectomy approach. Intra-operative crush smear and histopathological examination revealed a paraganglioma. Post-surgery the patient was treated with fractionated radiotherapy.
Keywords: Cerebellopontine angle, Crush smear, Fractionated radiotherapy, Paraganglioma
|How to cite this article:|
Arora S, Chakraborti S, Naik R, Ballal CK. Paraganglioma of left cerebellopontine angle. Indian J Otol 2013;19:68-71
| Introduction|| |
Paragangliomas (glomus tumors) are tumors of the specialized extra-adrenal neuroendocrine system and very rarely occur in the cerebellopontine angle (CPA). The overall location of paragangliomas is in accord with the sites of normal paraganglia that is the carotid, jugulotympanic and vagal body, etc., Usually, they are in close relation with vessels, nerves and the autonomic aorticosympathetic chain. 
| Case Report|| |
A 55-year-old female presented with complaints of ear pain and decrease hearing in the left ear of 1 year duration, and hoarseness of voice, difficulty in swallowing, nasal regurgitation, and tinnitus for last 3 months. Otological examination showed congested and bulged left tympanic membrane on its antero-superior surface and infero-posterior surface. Pure tone audiometry showed left sided profound sensorineural deafness. Neurological examination revealed fasciculation and wasting of the left side of the tongue with slight deviation to the right side, left vocal cord palsy and deficits in eighth, ninth, tenth, and twelfth cranial nerves.
Computed tomography (CT) of the brain shows a hyperdense and contrast enhancing lesion in the left CPA with erosion of the petrous temporal bone [Figure 1]a. Magnetic resonance imaging (MRI) of the brain showed homogenously enhancing lobulated, extra-axial, altered signal intensity lesion in the region of left CPA and extending into jugular foramen (pars nervosa compartment) eroding the basi-occiput, engulfing the left internal carotid artery antero-inferiorly and abutting the left sigmoid sinus posteriorly. The lesion was measuring 22 mm × 17 mm in the left CPA cistern and 23 mm × 31 mm in the jugular foramen. The lesion was isointense on T1, iso-to slightly hyperintense on T2 [Figure 1]c weighted images, brilliantly enhancing on contrast [Figure 1]b, and hyperintense on fluid attenuated inversion recovery [Figure 1]d sequence. Mild restriction was seen on diffusion weighted imaging. The lesion in the left CPA region lesion was abutting and partially engulfing the seventh and eighth cranial nerve complex. The radiological differential diagnosis was paraganglioma and non-acoustic schwannoma.
|Figure 1: Post-contrast axial computed tomography scan (a) at the level of the internal auditory canal (IAC) demonstrates enhancing left CPA mass. Post-contrast T1-weighted image (b) at the same level demonstrates intensely enhancing left CPA mass, without any extension of enhancement into the left IAC. Axial T2-weighted (c) and fluid attenuated inversion recovery (FLAIR) (d) images demonstrate a mass adjacent to the left jugular foramen having both intra-osseous and perimedullary cistern component, which is slightly hyperintense on T2-weighted image (c) and hyperintense on FLAIR image (d). There are multiple flow-voids on the FLAIR image and fluid in the left mastoid as well as in the left middle ear cavity (d). Post-contrast T1-weighted coronal image (e) and axial image (f) shows a left jugular foramen lobulated mass and extending up to the left CPA cistern|
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The patent underwent left retromastoid, posterior fossa craniectomy and exploration and excision of the tumor. Per-operatively the tumor was well-encapsulated, yellow in color and lifting the lower cranial nerves, and not arising from them. The tumor was highly vascular. Debulking of the tumor was done.
Crush smear for intra-operative consultation showed small- to medium-sized tumor cells with fine to coarse chromatin, and moderate amount of fine cytoplasm, arranged in dyscohesive sheets, clusters with insinuating capillaries, and singly scattered pattern [Figure 2]a: Rapid H and E, ×100]. Interspersed small cell with hyperchromatic nuclei were also seen [Figure 2]b: Rapid H and E, ×400]. The cytological features were consistent with paraganglioma. Microscopic examination of the paraffin embedded sections showed medium-sized tumor cells having fine to coarse chromatin, and a moderate amount of fragile cytoplasm [Figure 2]d: H and E, ×400] arranged in nests or zellballen pattern [Figure 2]c: H and E, ×100], rimmed by small to spindle-shaped cells with dark nuclei [Figure 2]d: H and E, ×400]. Numerous congested capillaries were seen in the tumor stroma [Figure 2]c: H and E, ×100]. The histological diagnosis was paraganglioma.
|Figure 2: Smear shows small-to medium-sized tumor cells with fine to coarse chromatin, and moderate amount of fine cytoplasm arranged in dyscohesive sheets, clusters and singly scattered pattern (a: Rapid H and E, ×100). Interspersed small cell with hyperchromatic nuclei were also seen (b: Rapid H and E, ×400). Histological examination revealed medium-sized tumor cells having fine to coarse chromatin (d: H and E, ×100), and moderate amount of fragile cytoplasm arranged in nests or zellballen pattern, rimmed by small to spindle-shaped cells with dark nuclei (c: H and E, ×100). Numerous congested capillaries were seen in the tumor stroma (c: H and E, ×100)|
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Surgery was followed by radiotherapy with 50 Gy in 25 fractions over 5 weeks. There was a significant improvement in the lower cranial nerve palsies. Presently, 1 year after surgery there is no recurrence of tumor.
| Discussion|| |
The review of literature by PubMed search (as on 26 th December 2012) shows that the first case of CPA paraganglioma, was reported by Erasmus in 1947,  following which less than twenty cases have been reported.
Though the lesions of the CPA are frequent and represent from 6% to 10% of all intracranial tumors. Vestibular schwannomas and meningiomas are the commonest, accounting for 85-90% the CPA tumors.  The other 10-15% cases encompass a wide variety of lesions, which include epidermal cyst, dermoid cyst, arachnoid cyst, miscellaneous cysts (neurocysticercosis, neurenteric cyst and neuroepithelial cyst), lipoma, aneurysm, melanoma, cholesterol granuloma, paraganglioma, chondroma and chondrosarcoma, chordoma, endolymphatic sac tumor, pituitary adenoma, apex petrositis, glioma, choroid plexus papilloma, lymphoma, hemangioblastoma, ependymoma, medulloblastoma, and dysembryoplastic neuroepithelial tumor. 
The prevalence of paraganglioma is low, accounting for only 0.6% of neoplasms of the head and neck region, with male preponderance (female to male ratio of 4:6.1) for jugulo-tympanic tumor, and maximum incidence in the fifth and sixth decades.  The classical evolution of this benign but locally aggressive tumor, is local invasion, follow paths of low resistance towards mastoid cell tracts, vascular channels and Eustachian tube More Details, destruction of the petrous bone, invade the CPA. Hence, paragangliomas of the CPA arise from minute bodies present in the jugular foramen along the vagus nerve (glomus jugulare tumor) or along the Jacobson nerve on the promontory of the middle ear (glomus tympanicum tumor).
A radiograph of the skull in cases of glomus jugulare tumor usually shows clouding of the mastoid air cells and erosion or destruction of the petrous or occipital bones or enlargement or destruction of the jugular foramen.  Paragangliomas on CT, appear as well-defined, enhancing soft tissue masses associated with moth-eaten erosion of the bony margins of the site of tumor origin (i.e., jugular foramen or promontory). On MRI, these soft-tissue masses are hypervascular, demonstrating punctate and serpentine signal voids produced by high-flow blood vessels. In addition, focal intra-tumoral hemorrhages appear as high signal intensity on T1-weighted images, producing a characteristic salt and pepper appearance and enhancing intensely after contrast material administration.  Radiologically, paraganglioma needs to be distinguished from acoustic schwannoma and meningioma, which are more common in the CPA. Acoustic schwannoma are round or oval masses in the cerebellopontine cistern that emerge from the internal auditory canal (IAC), widen the porus, and grow posteriorly, and can be heterogeneous due to cystic components. Conversely, meningiomas are usually hemispheric, semilunar, homogenous masses with a broad petrous base to which they are attached and are usually asymmetric to the IAC. 
Cytologic examination reveals medium polygonal, ovoid or elongated tumor cells are, which are either isolated or in loosely arranged groups or form rosettes. The cytoplasm is moderate to abundant, granular or dense eosinophilic on hematoxylin and eosin, and is pale on Papanicolaou stain. Red cytoplasmic granules are seen in Giemsa stain. The nuclei are round, centrally or eccentrically located and show considerable variation in size and shape, with granular chromatin. Rare intranuclear cytoplasmic inclusions are seen.  However, the cells in schwannomas are more spindled, arranged in fascicles, and tight clusters, having elongated, slender and wavy nuclei and focally show nuclear palisading. In meningiomas, the cells are medium-sized polygonal cells arranged in tight clusters, whorls or singly scattered, with oval, clear nuclei and psammoma bodies.
Histologically paraganglioma features epithelioid, small to medium-sized uniform chief cells with finely granular cytoplasm, arranged in clusters, nests or "Zellballen" pattern with peripheral flattened sustentacular cells, nests are separated by numerous blood vessels. Nuclei are usually uniform and small, but diagnosis is sometimes made difficult by the presence of bizarre or multinucleate cells which, however, do not indicate malignancy. The chief cells express synaptophysin, chromogranin and neuron-specific enolase, and are negative for cytokeratin, carcinoembryonic antigen, S-100 protein and calcitonin. The sustentacular cells express S-100 protein and glial fibrillary acidic protein. 
Surgical excision, though the primary treatment is complicated with per-operative bleeding because of high vascularity of the tumor.  Long-term control of the disease after surgery for jugular and vagal paranglioma was achieved in 78.2% and 93.3% of patients, respectively. Control of jugular paraganglioma with external beam radiotherapy (EBRT) and stereotaxic radiosurgery was achieved in 89.1% and 93.7% of the cases, respectively. Tumor control failure, major complication rates, and the number of cranial nerve palsies after treatment were significantly higher in surgical than in radiotherapy series. Conventional radiotherapy with fractionated EBRT has been used as a primary, combined, or salvage treatment in patients who cannot undergo surgery because of advanced age or comorbidity, larger, more aggressive, or unresectable tumors, or residual disease. 
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[Figure 1], [Figure 2]