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Clinical Consultation

Symptom: Pulsatile Mass in the Ear Canal

Rahhal, Romy MD; Tawk, Karen MD; Abouzari, Mehdi MD, PhD; Djalilian, Hamid R. MD

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doi: 10.1097/01.HJ.0000843276.91325.8f
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A 30-year-old man presented with occasional right-sided ear pain and headaches. His history is notable for a right canal wall down (CWD) mastoidectomy and for an unknown mastoid mass in 2011. The patient was lost to follow-up for many years. In September 2021, he was treated for an ear infection with ciprofloxacin and ofloxacin. The patient denies any other otologic symptoms. On examination, there was a CWD cavity filled with debris, which was cleaned. There was a smooth, fluid-filled, compressible skin-covered pulsatile mass located anterosuperiorly in the lateral external auditory meatus, which is shown in Figure 1.

F1
Figure 1:
Image of the patient’s ear. Hearing loss, pulsatile mass, ear canal.
F2
Figure 2:
Coronal (parallel to the face) CT of the right temporal bone showing the large defect in the tegmen mastoideum (bone separating brain from mastoid). Hearing loss, pulsatile mass, ear canal.
F3
Figure 3:
Coronal (parallel to the face) CT of the right temporal bone posterior to Figure 2 showing the large defect in the tegmen mastoideum. Hearing loss, pulsatile mass, ear canal.
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Figure 4:
Axial (horizontal) CISS sequence MRI of the internal auditory canal showing a fluid-filled mass in the right temporal bone. Hearing loss, pulsatile mass, ear canal.
F5
Figure 5:
Coronal (parallel to the face) CISS sequence MRI of the internal auditory canal showing a fluid-filled mass extending from the brain into the temporal bone. Hearing loss, pulsatile mass, ear canal.

DIAGNOSIS: MENINGOCELE

The examination of a post-operative ear requires diligence and, ideally, microscopic assistance. The patient had presented for unrelated symptoms and drainage issues, but careful examination revealed the mass. When evaluating an ear canal mass, malignancy should be considered as a potential etiology. A number of causes should be considered ranging from benign lesions, such as osteomas or exostoses, canal cholesteatomas, fibrous dysplasias, schwannomas, neurofibromas, nerve sheath myxomas and giant cell granuloma, to skin malignancies, salivary neoplasms, and metastases. 1 To begin, squamous cell carcinoma (SCCA), the most common malignancy of the ear canal, is unlikely in a young (30-year-old) patient but should always be considered. SCCA tends to occur in older patients. Also, SCCA is a tumor of the surface of the skin and will present as a fleshy ulcerated exophytic mass or an ulceration of the skin and a smooth, skin covered mass is unlikely to be SCCA. This finding, however, does not exclude malignancies arising from the subcutaneous tissue, as those can present as skin-covered masses as well. The most encountered subcutaneous malignancy in the ear canal would be an adenoid cystic carcinoma of the ceruminous glands. Although not likely to be encountered as frequently as the ones arising in salivary glands, other locations in the head and neck are still the second most common overall. Compressibility and its pulsatile nature are not consistent with an adenoid cystic carcinoma (ACC). Finally, ACCs occur in the cartilaginous canal where cerumen glands exist and this mass is in the bony portion of the canal (no overlying hair). When presented with a mass of unknown origin in the canal, which is subcutaneous, imaging is important for identifying the etiology. In a subcutaneous mass, it is important to obtain imaging before performing a biopsy of the mass. In a patient who has had previous surgery, computerized tomography (CT) scan of the temporal bone will show the bony anatomy and a magnetic resonance imaging (MRI) of the internal auditory canal with and without gadolinium enhancement can help better assess both the nature and origin of the mass. This can be followed by a careful biopsy if it is indicated.

A mass presenting in the ear canal of a patient who has undergone prior ear surgery requires consideration of other etiologies. First, it is always suspicious of an iatrogenic cholesteatoma. This occurs if some skin is implanted or left behind under the skin or if the edges of the skin are not turned out to line up in the canal. The leftover skin can continue to grow and accumulate keratin (dead skin) for years. We have seen patients who have had previous surgery 10-20 years prior with a slowly enlarging iatrogenic cholesteatoma. Other causes that must be considered in this context include an encephalocele, meningocele, and, more rarely, an anomalous venous or arterial structure, such as pseudoaneurysm of the carotid artery. Blind biopsies of a vascular structure (e.g., carotid artery) can lead to catastrophic results, such as uncontrolled bleeding or neurological deficits.

The patient underwent a CT scan of the temporal bone that showed post-operative changes noted to right CWD mastoidectomy with dehiscence of the temporomandibular joint, tegmen tympani, and a horizontal semicircular canal fistula, as well as membranous stenosis laterally in the canal (Figs. 2 and 3). A neoplastic mass on MRI will show enhancement with gadolinium on a T1 sequence. A CISS sequence MRI of the internal auditory canal shows a small right tegmen defect with a fluid-filled sac in the right ear, suspicious of meningocele (Figs. 4 and 5). The fluid-filled sac is continuous with the temporal lobe (Fig. 5).

Meningocele is defined as the herniation of the meningeal structures and the cerebral fluid through a bony defect. If the protrusion contains additional cerebral tissue, it is then called meningoencephalocele. It is most well-defined in the spinal region, while temporal bone meningoceles are extremely rare to encounter. Due to lack of exposure, physicians often misdiagnose this condition as tumors or polyps. Meningoceles in most cases are congenital neural tube defects. Yet, they can sometimes be spontaneous and acquired over time due to different pathologies. Temporal bone meningoceles can be developed as a result of defects created in the tegmen (bone separating the ear from the brain) in ear conditions such as cholesteatomas, infections, and head trauma or as a sequela of surgeries such as mastoidectomy or other intracranial surgeries. 2,3 In the head and neck region, meningoceles are most likely to occur in areas where the dura matter is surrounded by thin-layered skin and air-spaces meaning in the temporal bone or the paranasal sinuses. In the case of a temporal bone defect, one of the likely presentations is an external ear canal mass. Over time, the dura matter slowly herniates through the small bony openings, and aided by brain pulsations, can also lead to an encephalocele. Symptoms of temporal bone meningocele can range from no symptoms to all forms of otologic symptoms including gradual hearing loss and cerebral fluid. 3

Management of meningoceles is surgical and multiple techniques are available. With the lack of evidence-based guidelines, deciding on the best surgical approach is multidisciplinary and mainly relies on the size and location of the mass, its clinical impact, its etiology, the presence of cerebrospinal fluid leakage, the extent of the bony erosions, and the presence of concomitant ear pathologies. 2 The patient was advised that the conservative option carried its risks of meningitis, presenting cerebrospinal fluid leakage, closure of her ear canal, and worsening of her hearing. The surgical repair could be performed using a transmastoid or middle fossa approach. For larger defects (larger than 1 cm), the middle fossa allows better repair of the larger defect. This approach requires temporal lobe retraction and a longer inpatient stay. Our general approach is to attempt a transmastoid approach first and if not successful attempt the middle fossa approach next. The patient agreed to undergo surgery with a transmastoid approach. The defect was repaired with a large cartilage graft and bone.

BONUS ONLINE VIDEOS: VISUAL DIAGNOSIS

Read this month’s Clinical Consultation case, then watch the accompanying videos from Hamid R. Djalilian, MD, to review the patient’s imaging for yourself.

Video 1. Axial (horizontal) CT of the right temporal bone showing post-operative changes with canal wall down mastoidectomy and erosion of the TMJ.

Video 2. Coronal (parallel to the face) CT of the right temporal bone showing large tegmen defect in the mastoid.

Video 3. Axial (horizontal) CT of the left temporal bone demonstrating the normal anatomy of the left side.

Video 4. Coronal (parallel to the face) CT of the left temporal bone showing the normal anatomy of the left side.

Video 5. Axial (horizontal) CISS sequence MRI of the internal auditory canal showing a fluid-filled mass in the right temporal bone (based on axial scans, it is unclear if this mass involves the brain or not).

Video 6. Coronal (parallel to the face) CISS MRI of the internal auditory canal shows that the fluid filled mass is continuous with the brain and extends into the mastoid on the right (right side of images). Note that this MRI is flipped and normally the right side of the patient would be on the right side of the images.

Video 7. Video of the patient’s examination.

Watch the patient videos online at thehearingjournal.com.

REFERENCES

1. Yalamanchi P, Basura GJ 2020 More than meets the eye: A reportedly isolated ear canal mass Otolaryngology Case Reports 16 100206 https://doi.org/10.1016/j.xocr.2020.100206
2. Alijani B, Bagheri HR, Chabok SY, Behzadnia H, Dehghani S 2016 Posttraumatic temporal bone meningocele presenting as a cystic mass in the external auditory canal Journal of Craniofacial Surgery 27 e481 e484 https://doi.org/10.1097/scs.0000000000002803
3. Kamerer DB, Caparosa RJ 1982 Temporal bone encephalocele--diagnosis and treatment Laryngoscope 92 8 Pt 1 878 882 https://pubmed.ncbi.nlm.nih.gov/7098736/
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