Glomus tympanicum paragangliomas (chemodectomas) are the most common middle ear tumor.
There is a female predominance (M: F = 1:3); presentation is most common when patients are more than 40 years old 1,2.
CT is usually the best modality to assess these masses.
- soft tissue mass lateral to the cochlear promontory
- ossicles may or not be destroyed and may simply be encased
- surrounding bony destruction may be present in aggressive tumors
- intact jugular bulb
The Glasscock-Jackson and Fisch classifications of glomus tumors 5 are based on the local extension of the tumor and their effect on mortality and morbidity. Glomus tympanicum paragangliomas are considered type A tumor, as they are limited to the middle ear cavity.
Treatment and prognosis
Surgical resection is the treatment of choice 4.
On imaging consider:
glomus jugulare paraganglioma
- permeative destruction of the floor of the middle ear
- involving the jugular foramen
- presents with a dehiscent jugular bulb
facial nerve schwannoma
- pedunculated mass arising from the facial nerve
- involving the tympanic segment of the facial nerve
- no enhancement on post-contrast T1 MRI
- 1. Lee KY, Oh YW, Noh HJ et-al. Extraadrenal paragangliomas of the body: imaging features. AJR Am J Roentgenol. 2006;187 (2): 492-504. doi:10.2214/AJR.05.0370 - Pubmed citation
- 2. Larson TC, Reese DF, Baker HL et-al. Glomus tympanicum chemodectomas: radiographic and clinical characteristics. Radiology. 1987;163 (3): 801-6. doi:10.1148/radiology.163.3.3033738 - Pubmed citation
- 3. Lum C, Keller AM, Kassel E et-al. Unusual eustachian tube mass: glomus tympanicum. AJNR Am J Neuroradiol. 2001;22 (3): 508-9. AJNR Am J Neuroradiol (full text) - Pubmed citation
- 4. Radiology of the Petrous Bone. Springer. ISBN:354042394X. Read it at Google Books - Find it at Amazon
- 5. C. Gary Jackson, Michael E. Glasscock, Perry F. Harris. Glomus Tumors: Diagnosis, Classification, and Management of Large Lesions. (1982) Archives of Otolaryngology. 108 (7): 401. doi:10.1001/archotol.1982.00790550005002 - Pubmed