Chapter 24: Tumors of the Temporal Bone

Selected Benign Tumors

See Table 24-1.

Glomus Tumor (Paraganglioma)

1. Most common neoplasm of the middle ear and second most common neoplasm of the temporal bone/cerebellopontine angle (CPA)

   1. Glomus tympanicum (GT)

   2. Glomus jugulare (GJ)

   3. Glomus vagale (GV)

2. Caucasians more commonly affected

3. Also known as chemodectoma

4. M:F—1:5

5. May be multicentric (10%)

6. Majority are sporadic; up to 30% are familial

7. Rarely malignant—(2%-4%) with highest risk in vagal paragangliomas

   1. Diagnosis requires metastasis to non-neuroendocrine tissue

   2. Most common sites are nodal, bone, lung, liver, and spleen

8. Rarely functional—5% or less secrete neuroactive peptides (palpitations, sweating, flushing, syncope, hypertension, headaches)

   1. May result in catastrophic hypertension upon induction of anesthesia if not identified and treated preoperatively.

   2. If secretory treat with phentolamine (nonselective reversible alpha-adrenergic agent).

   3. Functional tumors are rare in extra-adrenal locations.

9. Biology

   1. Arise from chemoreceptor cells of the neuroendocrine system

      1. Derived from parasympathetic paraganglia in the head and neck

         Found in the jugular dome, tympanic promontory, along Jacobson and Arnold nerves

      2. Type I chief cells, and type II sustentacular cells

   2. Genetics

      1. 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).

         1. Thought to be the mutation in sporadic tumors as well

      2. SDH mutations result in pseudohypoxia and upregulation of hypoxia inducing factor 1-alpha.

      3. SDHD and SDHC have the highest risk of developing head and neck paragangliomas.

      4. Phenotype is maternally imprinted (ie, passed on via male carrier).

         1. Explains why phenotype can skip a generation

         2. Autosomal dominant

10. Classification schemes (Table 24-3)

    1. Fisch

    2. Glasscock-Jackson

       1. Glomus tympanicum

       2. Glomus jugulare

11. Diagnosis

    1. Symptoms

       1. Pulsatile tinnitus (80%) (GT and GJ)

       2. Hearing loss, conductive or mixed (60%) (GT and GJ)

       3. Otalgia (13%) (GT and GJ)

       4. Aural fullness (32%) (GT and GJ)

       5. Hoarseness/dysphagia (15%) (GJ)

       6. Facial weakness (15%) (GT and GJ)

       7. Functional tumors will present with palpitations, unexplained weight loss, poorly controlled hypertension

    2. Physical examination

       1. Middle ear mass

          1. For diagnosis GT must be able to see 360 degrees around mass, otherwise adjunctive imaging required for diagnosis

          2. Brown sign—blanching of middle ear mass with pneumatic otoscopy

       2. External auditory canal (EAC) mass

       3. Neck mass or pharyngeal fullness

       4. Cranial nerve deficits including lower cranial nerve examination

          1. Audiogram (GT and GJ)

          2. Laryngoscopy (GJ)

    3. Diagnostic workup

       1. Urine for vanillylmandelic acid (VMA), metanephrines

          1. Must be five times higher ...