Selected Benign Tumors
See Table 24-1.
|Direct extension of tumors from surrounding areas|
|Glomus tympanicum||Adenoid cystic carcinoma|
|Hemangioma||Acinic cell carcinoma|
Endolymphatic sac tumor
|Petrous Apex||Schwannoma (facial/vestibular)||SCCA|
|Chondrosarcoma||Metastatic carcinoma to the temporal bone (TB)|
|Direct extension of tumors of the surrounding area|
Most common neoplasm of the middle ear and second most common neoplasm of the temporal bone/cerebellopontine angle (CPA)
Glomus tympanicum (GT)
Glomus jugulare (GJ)
Glomus vagale (GV)
Caucasians more commonly affected
Also known as chemodectoma
May be multicentric (10%)
Majority are sporadic; up to 30% are familial
Rarely malignant—(2%-4%) with highest risk in vagal paragangliomas
Diagnosis requires metastasis to non-neuroendocrine tissue
Most common sites are nodal, bone, lung, liver, and spleen
Rarely functional—5% or less secrete neuroactive peptides (palpitations, sweating, flushing, syncope, hypertension, headaches)
May result in catastrophic hypertension upon induction of anesthesia if not identified and treated preoperatively.
If secretory treat with phentolamine (nonselective reversible alpha-adrenergic agent).
Functional tumors are rare in extra-adrenal locations.
Arise from chemoreceptor cells of the neuroendocrine system
Derived from parasympathetic paraganglia in the head and neck
Found in the jugular dome, tympanic promontory, along Jacobson and Arnold nerves
Type I chief cells, and type II sustentacular cells
Familial tumors are caused by genetic defect in mitochondrial DNA encoding for succinyl dehydrogenase subunits B, C, or D (SDHB, SDHC, SDHD) of mitochondrial complex II; involved in mitochondrial electron transport chain (Table 24-2).
Thought to be the mutation in sporadic tumors as well
SDH mutations result in pseudohypoxia and upregulation of hypoxia inducing factor 1-alpha.
SDHD and SDHC have the highest risk of developing head and neck paragangliomas.
Phenotype is maternally imprinted (ie, passed on via male carrier).
Explains why phenotype can skip a generation
Classification schemes (Table 24-3)
Pulsatile tinnitus (80%) (GT and GJ)
Hearing loss, conductive or mixed (60%) (GT and GJ)
Otalgia (13%) (GT and GJ)
Aural fullness (32%) (GT and GJ)
Hoarseness/dysphagia (15%) (GJ)
Facial weakness (15%) (GT and GJ)
Functional tumors will present with palpitations, unexplained weight loss, poorly controlled hypertension
Middle ear mass
For diagnosis GT must be able to see 360 degrees around mass, otherwise adjunctive imaging required for diagnosis
Brown sign—blanching of middle ear mass with pneumatic otoscopy
External auditory canal (EAC) mass
Neck mass or pharyngeal fullness
Cranial nerve deficits including lower cranial nerve examination
Audiogram (GT and GJ)
Urine for vanillylmandelic acid (VMA), metanephrines
Must be five times higher than normal to be symptomatic
Used to exclude a functional component
Computed tomography (CT) IAC—imaging modality of choice
Used to evaluate extent of lesion
GT—used to classify tumor as GT or GJ if diagnosis is unclear from physical examination
Evaluate extent of carotid canal involvement for GJ
Differentiate mass from high-riding jugular bulb or aberrant carotid
Infiltrative and erosive into the bone
Magnetic resonance imaging (MRI) with contrast
Identify the extent of the lesion and assess intracranial extension
Classic “salt and pepper” appearance due to flow voids within the tumor
CT and MRI are complementary in the skull base
Four-vessel angiography to identify feeding vessels
Embolization of the feeding vessels should be performed 24 to 48 hours prior to surgical resection
Significantly improves intraoperative blood loss
Preoperative balloon occlusion testing using 99TmTc-HMPAO SPECT scanning or Xenon CT of the ipsilateral carotid should be performed if imaging suggests arterial invasion
Glomus tumors are a surgical disease unless patient’s comorbidities prevent operation
Small tumors limited to the promontory can be removed via a transcanal or anterior tympanotomy approach
Larger tumors require wider exposure via mastoidectomy and posterior tympanotomy
Requires proximal control of the great vessels in the neck and the sigmoid sinus
Large tumors may require transposition of the facial nerve to expose the tumor anteriorly
Infratemporal fossa approach (Fisch type A) is a method of choice for removal
Considerable care is required to preserve the lower cranial nerves (CN IX-XII)
For very large tumors—may need to stage the procedure if blood loss more than 3 L during removal of tumor from the neck and temporal bone; intracranial resection can proceed at a later date
Can be used as primary modality, or for residual or recurrent disease
Used to prevent further tumor growth
Mechanism of action—obliterative endarteritis
Lower doses are used for single fraction (15 Gy) and external beam (40-45 Gy)
Stereotactic radiosurgery (SRS) has reported 90% to 94% rate of tumor control
Risks of SRS: radiation-induced malignancy, osteoradionecrosis of the skull base, temporal lobe necrosis, cranial nerve injury
|Gene||Tumor Syndrome||Locus||Inheritance||Head and Neck||Adrenal||Risk of Malignancy||Unique Features|
|SDHC||PGL3||1q21||AD||88%||< 10%||< 10%||Single tumors|
|SDHA||PGL5||5p15.33||AD||<3%||< 10%||< 10%|
|Type A||Limited to the middle ear|
|Type B||Limited to the tympanomastoid area with no involvement of the infralabyrinthine compartment|
|Type C||Involves the infralabyrinthine compartment and petrous apex|
|C1—limited involvement of carotid canal|
|C2—invasion of the vertical portion of carotid canal|
|C3—invasion of the horizontal portion of the carotid canal does not involve the foramen lacerum|
|C4—involves the entire course of the intrapetrous carotid|
|Type D||Intracranial extension|
|De1—extradural, extension of < 2 cm|
|De2—extradural, extension of > 2 cm|
|Di1—intradural, extension of < 2 cm|
|Di2—intradural, extension of > 2 cm|
|Type I||Limited to the promontory|
|Type II||Completely filling the middle ear|
|Type III||Filling middle ear and extending into the mastoid|
|Type IV||Filling middle ear into the mastoid, tympanic membrane (TM) and into the external auditory canal (EAC) (may extend anterior to the internal carotid artery)|
|Type I||Small tumor involving the jugular bulb, middle ear, and mastoid|
|Type II||Extending under the internal auditory canal (IAC), may have intracranial extension|
|Type III||Extending into petrous apex, may have intracranial extension|
|Type IV||Extending beyond the petrous apex into the clivus or infratemporal fossa, may have intracranial extension|
Locally aggressive, slow-growing neoplasm originating from the endolymphatic sac or duct.
Histologically described as a destructive papillary cystic adenomatous tumor of the temporal bone.
Lack of transthyretin (prealbumin) staining, which is seen in choroid plexus tumors, confirms an endolymphatic sac tumor.
Positive staining for cytokeratin, vimentin, and S-100, negative for chromogranin (paraganglioma), negative for thyroglobulin (metastatic thyroid cancer).
Sporadic tumors are more common than von Hippel-Lindau (VHL)-associated disease.
Diagnosis typically occurs in the fifth and sixth decade in sporadic tumors and the third and fourth decades in VHL-associated tumor.
VHL-associated tumors are more commonly seen in females, whereas sporadic tumors have no gender predilection.
11% of VHL patients will develop endolymphatic sac tumors, of which 30% will be bilateral.
VHL caused by loss of function of tumor-suppressor gene located on chromosome 3p25.5.
Ubiquitin ligase that targets hypoxia inducing factor 1-alpha (HIFs). HIFs regulate angiogenesis and metabolism.
Screening with cranial MRI every 1 to 3 years is appropriate in VHL patients.
Typically involves the sac and the endolymphatic duct.
Dysfunction of the otic capsule is the most common presenting symptom.
Symptoms often mimic endolymphatic hydrops, likely due to obstruction of the normal flow and resorption patterns of endolymph.
Sensorineural hearing loss, followed by tinnitus, vertigo, and aural fullness are the most common symptoms, respectively.
Sudden hearing loss typically results from intralabyrinthine hemorrhage.
Middle ear extension can mimic Eustachian tube dysfunction and otitis media.
Late symptoms include facial paralysis, symptoms of brain stem compression, and lower cranial neuropathies.
No cases of distant metastasis have been reported, but drop metastasis into the thecal sac causing lower extremity weakness has been reported.
CT—bony destruction of the posterior fossa plate centered over the operculum with central calcifications; may extend into the mastoid as well
T1—heterogeneous, hypo, iso, or hyperintense. Hyperintensity secondary to intralesional hemorrhage (methemoglobin, hemosiderin, cholesterol crystals), hypointensity reflects residual bone or calcifications
T2—heterogeneous (suggesting its highly vascular nature)
T1 with gadolinium—heterogeneous enhancement
Hypervascular lesion that may benefit from preoperative embolization
External carotid supply, but can also have contributions from the internal carotid or vertebral arteries
Blood supply typically from the inferior tympanic or a dural branch of the stylomastoid artery which arise from the ascending pharyngeal and postauricular artery, respectively
Differential—paraganglioma, choroid plexus tumor, metastasis, eosinophilic granuloma, meningioma, arachnoid granulation, aneurysmal bone cyst, primary bone tumors
Surgery is the method of choice.
Should involve removal of both surfaces of the dura to ensure complete removal
Hearing sparing approaches for small tumors
Patients with nonserviceable hearing
Large tumors can be preoperatively embolized to minimize blood loss