Diagnosis: Malignant Otitis Externa
It is common for patients to see multiple clinicians. However, some clinicians don't always review data from other sources usually due to lack of access. In our practice, we encourage patients to bring all records including imaging to allow the clinician to evaluate all available information at the same time to make the most accurate diagnosis. This patient was asked to bring her biopsy results and imaging to help establish a proper diagnosis and treatment.
When dealing with a patient with an ear canal mass and facial paralysis, the first step is to determine the origin of the mass via tissue biopsy. In this patient's case, the tissue biopsy showed inflammation. In cases where the mass does not appear to be consistent with the inflammation, a re-biopsy is needed to make sure that a tumor is not missed. Ear canal mass with facial paralysis could sometimes represent a glomus jugulare tumor that came through the ear canal and presented as an ear canal mass. Biopsy of a glomus tumor can lead to significant bleeding since it's a highly vascular tumor. In a patient with end-stage renal disease, a condition wherein platelet function is often not normal, biopsy of a glomus tumor can cause significant hemorrhage. Another tumor to consider in this situation is squamous cell carcinoma of the ear canal.
In general, a fleshy ear canal mass is more likely to be a granulation tissue than a malignant or glomus tumor. However, clinicians must not assume that a mass is a granulation if it has been persistent for over three weeks and there are other conditions like pain, abnormalities such as facial paralysis, or history of skin cancer around the ear. With instrumentation, clinicians can move around the mass and determine its origin to have a better idea of its nature. In its early stage, a malignancy can be localized to a small area in the ear canal. Granulation tissue can be compressed and flattened using a silver nitrate stick. In the absence of recent otologic surgery, granulation tissue tends to be more peduncular, coming off from a single spot in the ear canal with a large part of the mass in the lumen of the canal. The clinician can twirl a silver nitrate stick to amputate the granulation tissue and cauterize the base. The mass that is removed could then be sent for pathological examination. Even when the mass represents a granulation tissue, it is imperative to determine the underlying cause of the granulation. Granulation tissue that originates from the eardrum is usually due to an underlying cholesteatoma until proven otherwise. Ear canal granulation can be from a foreign body reaction to an implanted fiber or sand during manipulation of the ear canal.
In this patient, CT scan of the temporal bones showed that there was destruction of the anterior canal wall and widening of the facial nerve canal. The mastoid was opacified and likely filled with fluid. The patient's right side (unaffected side) was normal with good aeration and a normal facial nerve canal (Figs. 2 and 3).
The MRI imaging (Fig. 4) showed an enhancement along the soft tissues and the bone of the skull base. Such enhancement indicates increased blood flow to these areas, which could mean a mass or inflammation. In this case, evaluation of the T2 MRI (Fig. 5) showed hyperintensity (increased fluid in tissues) along the entire left temporal bone. The increased fluid in the tissues was due to the increased inflammation and blood flow to the area from a likely infectious process.
Upon reviewing all of the patient's information, we learned that the patient had granulation in the ear canal at the bony cartilaginous canal (based on biopsy), diabetes (which causes immunosupression), purulence in the ear canal, and severe pain in the ear. A mass at the bony cartilaginous junction in the presence of ear pain and diabetes (or any type of immunosuppression) is most likely due to malignant otitis externa (skull base osteomyelitis). Given the strong indication for this diagnosis and the patient's previous negative biopsy, we elected to not biopsy the mass.
Malignant otitis externa (also known as skull base osteomyelitis or necrotizing otitis externa) is a potentially life-threatening condition that usually affects diabetics and people with immunosuppression, e.g., HIV, chemotherapy, transplant, kidney failure, patients on immunosuppressive agents (e.g., chronic prednisone or other agents; Laryngoscope. 2008 Nov;118:1917-24). The clinical diagnosis was confirmed via blood testing, which showed a high sedimentation rate (ESR) and/or Creactive protein (CRP), and a technetium 99 bone scan (a nuclear medicine study) that further solidified the diagnosis. A technetium SPECT scan that creates sliced images is preferred for a more precise localization of the infection.
Malignant otitis externa is treated with intravenous antibiotics directed at the bacterial culture for at least six weeks (Otol Neurotol. 2006 Feb;27(2):250-5). Culture can be obtained from the ear or sometimes by performing a tissue biopsy of the granulation in the ear canal. Patients also need to get a series of blood tests (ESR and CRP) and gallium 67 SPECT scans in the follow-up. This patient's ESR was 87 (normal <25) and CRP was 5.0 (normal <1.0). After three days of antibiotics, her ESR decreased to 70 and CRP to 2.0, indicating that the antibiotics were working against the infection. The patient received long-term intravenous antibiotic treatment.
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) bone window CT of temporal bones two weeks prior to presentation showing the destruction of the anterior canal.
- Video 2. Axial (horizontal) soft tissue window CT of temporal bone showing that the ear canal is filled with soft tissue.
- Video 3. Coronal (parallel to face) bone window CT of temporal bone demonstrating the significantly enlarged facial nerve canal.
- Video 4. Axial T1 post-gadolinium MRI showing no distinct mass in the ear canal.
- Video 5. Axial T2 MRI showing significant inflammatory changes in the entire temporal bone.
- Video 6. Coronal T1 post-gadolinium MRI showing the inflammation along the skull base.
Watch the patient videos online at thehearingjournal.com https://journals.lww.com/thehearingjournal/Pages/collectiondetails.aspx?TopicalCollectionId=23.
1. Rothholtz VS, Lee AD, Shamloo B, Bazargan M, Pan D, Djalilian HR Skull base osteomyelitis: the effect of comorbid disease on hospitalization. Laryngoscope
. 2008 Nov;118(11):1917-24.
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2. Djalilian HR, Shamloo B, Thakkar KH, Najme-Rahim M Treatment of culture-negative skull base osteomyelitis. Otol Neurotol
. 2006 Feb;27(2):250-5.