|Year : 2017 | Volume
| Issue : 2 | Page : 131-133
Glomus tympanicum: A radiological dilemma
A Karunagaran, VJ Niranjana Bharathi, Anand Karthikeyan
Department of ENT, SRM Medical College Hospital and Research Centre, Kancheepuram, Tamil Nadu, India
|Date of Web Publication||14-Jun-2017|
Department of ENT, SRM Medical College Hospital and Research Centre, Potheri, Kancheepuram - 603 203, Tamil Nadu
Source of Support: None, Conflict of Interest: None
Glomus tumors are non chromaffin paraganglionomas, a vascular tumor arising in the middle ear, presents with tinnitus and aural block with radiological supportive findings. Diagnosis is made easy by the radiological investigations. Even in this modern era, the role played by clinical examination is vital and as we present in this case report, played an important role in management of the disease.
Keywords: Computed tomography temporal bone, glomus tympanicum, tinnitus
|How to cite this article:|
Karunagaran A, Niranjana Bharathi V J, Karthikeyan A. Glomus tympanicum: A radiological dilemma. Indian J Otol 2017;23:131-3
| Introduction|| |
Glomus tumors, also called nonchromaffin cell paragangliomas, arise from neural crest cells. Glomus tympanicum is associated with the Jacobson's nerve, a branch of glossopharyngeal nerve. The tumor is typically vascular and grows from capillary and precapillary vessels in-between epithelial cells. In the temporal bone, glomus tumors can either present as glomus tympanicum or glomus jugulare. The most common presenting symptoms are pulsatile tinnitus and hearing loss. Imaging studies (computerized tomography [CT] and magnetic resonance imaging [MRI]) are necessary for diagnosis. In this case report, we discuss a case which presented with typical symptoms of glomus tumor and contradictory imaging studies. The histopathology and immunohistochemistry were conclusive of glomus tympanicum.
| Case Report|| |
A 56-year-old lady presented to ENT outpatient department with symptoms of right aural fullness/blockade for 6 months. She also had a complaint of pulsatile tinnitus and hard of hearing in the same ear for 6 months. There was no history of ear pain, otorrhea, vertigo, headache, and facial weakness. No other comorbidities were present. Otoendoscopy revealed reddish and bulged out right tympanic membrane [Figure 1].
Preauricular and postauricular examinations were normal. A provisional diagnosis of glomus tumor was made. Left ear was clinically normal. Tuning fork tests and pure tone audiometry revealed a conductive hearing loss pattern [Figure 2].
Impedance audiometry showed a “B curve” in right ear and “A curve” in left ear.
Plain computerized tomogram of the temporal bone revealed a soft tissue density in the middle ear cavity. Bilateral jugular fossa and carotid canal showed intact bony wall. There was no bony dehiscence seen.
MRI was suggestive of right otomastoiditis. Magnetic resonance angiogram was normal with no vascular loops. Contrast-enhanced CT too was suggestive of right otomastoiditis with granulation. Bilateral jugular fossa and carotid canal showed intact bony wall. No bony dehiscence was seen.
With the above investigatory findings, the patient was taken up for tympanomastoid exploration surgery with proper informed consent of patient. Peroperatively, a thick capsulated vascular mass was seen arising from the promontory. It was seen involving the anterior part of mesotympanum and part of anterior hypotympanum. It was not involving the round window or attic region. During the procedure, due to inaccessibility for the instruments and bipolar cautery, a canal wall down approach was taken and the middle ear mass was removed after canal wall down procedure. Peroperatively, the thick capsulated vascular mass was bleeding profusely and bipolar cautery was used to secure hemostasis. This was a suggestive of a vascular tumor.
The postoperative histopathological examination suggested the mass to be a glomus tumor – angiomatous type [Figure 3].
Immunohistochemistry was done with smooth muscle actin [Figure 4] and vimentin [Figure 5] markers. Both of which confirmed the mass to be glomus tumor – angiomatous type.
Therefore, the tumor was diagnosed to be glomus tympanicum and was classified postoperatively as glomus tympanicum Type A (Fisch) and Type B (Glasscock and Jackson).
| Discussion|| |
Tumors of temporal bone are rare and usually present with the symptoms of hearing loss and tinnitus. Diagnosis is often delayed due to the slow growth of the tumor. Glomus tympanicum tumors are more common than glomus tumors around the jugular vein and are the most common primary neoplasm of the middle ear and the second most common tumor of the temporal bone. In 1941, Guild first described “glomic tissue” in temporal bone as a vascular tissue in the dome of the jugular bulb and the promontory of middle ear. Subsequently, in 1945, Rosenwasser  reported a “carotid body tumor” of the middle ear and mastoid referring to it as glomus tumor. Later, Guilford and Alford coined the term glomus tympanicum to describe those paragangliomas limited to the middle ear.
Glomus tumors occur with an estimated annual incidence of 1 case per 1.3 million people. Most tumors occur in patients aged 50–60 years. The female-to-male ratio is 4:1. Although benign, it is locally destructive. The term “glomus” is a misnomer – initially thought to originate from true glomus complexes. Glomus tumors arise from paraganglions which are in close association with sympathetic ganglions. Chief cells of paraganglions are of neural crest origin and are components of diffuse neuroendocrine system. Type I cells of the amine precursor uptake and decarboxylation system are present in glomus tumors. Glomus tumors, also called nonchromaffin cell paragangliomas, are benign tumors. In the temporal bone, it is of two types – glomus tympanicum and glomus jugulare. The tumor is typically vascular and grows from capillary and precapillary vessels in-between epithelial cells. It derives its vascular supply from the inferior tympanic branch of ascending pharyngeal artery. Paraganglia of the temporal bone are ovoid, lobulated bodies found accompanying Jacobson's and Arnold's nerves. Arnold's nerve is the auricular branch of the vagus nerve. Jacobson's nerve is the inferior tympanic branch of the glossopharyngeal nerve. Microscopically, they consist of clusters of Type I or catecholamine-containing chief cells (zellballen) and Type II or sustentacular cells (modified Schwann cells), intimately interlaced with a rich network of capillaries and venules.
The most common presenting symptoms are pulsating tinnitus and hearing loss. Conductive hearing loss occurs when tumor impairs the normal vibration of the ossicles or bones behind the ear drum. A sensorineural hearing loss and/or dizziness can result rarely if the tumor has invaded the inner ear. Other symptoms may include aural hemorrhage or otorrhea, otalgia, and facial palsy. Aquino's sign is the blanching of the tympanic mass with gentle pressure on the carotid artery, while Brown's sign describes the pulsation elicited by pneumatic compression that is abolished with further compression. On physical examination, the hallmark of a jugulotympanic glomus tumor is a reddish-blue mass seen behind the tympanic membrane.
Imaging studies (CT and MRI) are the primary imaging modalities for diagnosis. CT scan is a hallmark of jugulotympanic glomus tumors. On CT scan, glomus tympanicum appears as a soft tissue mass abutting the promontory of the middle ear. The presence of air or bone between the tumor and jugular bulb virtually assures the diagnosis of tympanicum. MRI is better than CT for delineating tumor edges and intracranial extent. In MRI, glomus tumors have a typical salt and pepper appearance.
Preoperative embolization of feeding vessels is useful if performed within 48 h of planned surgery. Surgery is the main treatment modality. Radiotherapy is also given in some cases.
| Conclusion|| |
Glomus tumors have well been discovered and treated before the introduction of imaging studies in our medical system. Today, most of us rely only on investigations to arrive at a diagnosis. Hence, even in the era of imaging studies, emphasis has to be placed on history taking and examination as an important pointer for diagnosis.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]