A 75-year-old man presented with hearing loss that had been going on for the past two years; the hearing loss was worse in his right ear. He had no significant medical history, and denied any history of ear infections, otalgia, otorrhea, dizziness, tinnitus, otologic surgery, or trauma. Physical examination of his right ear is shown in Figure 1. His right tympanic membrane was retracted and had a blue-purple hue. Examination of his left ear was normal. His audiogram revealed a 35 dB air-bone gap with moderate to moderately severe mixed hearing loss, a flat tympanogram in the right ear, and mild sensorineural hearing loss and a normal tympanogram in the left ear.
Diagnosis: Middle Ear Cholesterol Granuloma
The combination of a blue tympanic membrane and conductive hearing loss should prompt a clinician to consider a few diagnoses, the first and most common of which is a high-riding jugular bulb. Blood from inside the skull drains through the sigmoid sinus into the jugular bulb and eventually out of the skull via the internal jugular vein. The jugular bulb normally does not extend beyond the hypotympanum; however, high-riding jugular bulbs that extend past the limit of the hypotympanum such that they become visible behind the tympanic membrane, which occurs in 10 to 15 percent of the population. A high-riding jugular bulb by itself is usually not a cause for concern, but in up to three percent of these cases, the high-riding jugular bulb can become dehiscent and erode structures in the middle ear, causing conductive hearing loss and pulsatile tinnitus (Laryngoscope. 2013 Jul;123:1803-5).
A second consideration is hemorrhage, which can have many etiologies. Eustachian tube dysfunction resulting in vigorous ear popping, trauma including temporal bone fracture and barotrauma, and cholesterol granulomas can all cause hemorrhage in the middle ear. Though we normally imagine blood as being bright red, venous blood is often darker and more purple in color, which is an effect of lower oxygen content on the hemoglobin. While barotrauma causes bleeding behind the tympanic membrane, it is usually limited and seen just anterior to the malleus. Patients are often surprised when we ask them in the office if they were on an airplane recently after visualizing a thin rim of blood just anterior to the malleus. Temporal bone fracture can cause bleeding in the middle ear. Patients usually report trauma, though some patients may have to be prompted to provide the history of a fall or trauma to the occipital or temporal areas. When viewed through the overlying tympanic membrane, this blood usually appears purple, blue, brown, or gray.
A rare consideration is a middle ear mass such as a meningocele or vascular tumor. Meningoceles are extensions of the dura that can involve the mastoid or middle ear. They usually present with a pulsatile trabecular meshwork (TM) motion and can lead to a CSF leak. It is uncommon for them to extend to the floor of the middle ear given the presence of ossicles. Vascular tumors of the middle ear (e.g., glomus tympanicum or middle ear adenoma) appear more red and pulsate when visualized with microscopy.
Cholesterol granuloma is a cyst that contains fluid. A cyst can form around the hemorrhagic fluid. While cholesterol granuloma is most commonly associated with a petrous apex lesion, it can occur in the middle ear and the mastoid as well. The fluid in the cyst is usually described as motor oil in color. However, when present behind the tympanic membrane, it will appear blue. These two predominant theories explain how these masses are formed: (1) Eustachian tube dysfunction and repeated vacuum pressure on the middle ear mucosa eventually cause bleeding, and (2) aggressive growth of the mucosa exposes the underlying vascular bone marrow, which also results in bleeding. Either way, an inflammatory response is provoked, and the blood is then surrounded by expansile cysts that subsequently form a cholesterol granuloma. In the past, all cholesterol granulomas were drained, but we now understand that some of these are not progressive and destructive and can be observed.
Imaging is needed to evaluate any of the above etiologies and narrow down the diagnosis. A high-riding jugular bulb can be visualized on both CT and MRI; however, a dehiscent jugular bulb, denoted by the absence of the overlying bone, is often only visualized on CT because it is too thin to be seen on MRI. Hemorrhage and hemotympanum will appear as opacification of the middle ear on CT and MRI. Cholesterol granulomas may appear as a distinct lesion on CT or cause opacification due to bleeding. On MRI, cholesterol granulomas will show hyperintensity (brighter than the brain) on both T1- and T2-weighted images. MRI will also aid in the evaluation of other masses such as meningoceles. This patient's imaging was characteristic of a middle ear cholesterol granuloma with hyperintense fluid on T1- and T2-weighted images (Figs. 2 and 3).
A CT scan of the IACs was obtained for the patient, which showed opacification of the right middle ear cavity consistent with cholesterol granuloma that was non-destructive (Figs. 4 and 5). The ossicles were preserved and not destroyed in the process.
The treatment for a cholesterol granuloma involves either surgery or watchful waiting. If the granuloma is stable in size and not causing any neurological dysfunction or encroaching on the middle ear structures, observation alone can be considered. When the cholesterol granuloma must be surgically treated, the extent of the procedure depends on the location of the mass and varies from a simple ventilatory tube placement for middle ear cholesterol granulomas to endoscopic approaches, transmastoid, or craniotomy for petrous apex cholesterol granulomas (Otolaryngol Head Neck Surg. 2009 Jun;140:880-3.). The goal in all cases is to drain the cyst to prevent it from getting bigger. Complete resection of the cholesterol granuloma is usually not necessary and extremely difficult since the cyst wall is extensive. In the case of this patient with a middle ear cholesterol granuloma, an in-clinic myringotomy and tube placement are sufficient to let the mass drain and prevent further erosion of vital structures. The patient got an in-clinic tube placement and had immediate improvement in hearing.
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) CISS images demonstrating hyperintense (brighter than the brain) fluid in the middle ear and mastoid on the right (left side of the images).
- Video 2. Axial (horizontal) T1 showing the hyperintense fluid in the right middle ear.
- Video 3. Axial DWI showing no hyperintensity, indicating the absense of cholesteatoma in the temporal bone.
- Video 4. Coronal (vertical, parallel to the face) T1 fat-suppressed post-contrast, which shows the mastoid fluid to be darker and the middle ear component hyperintense (brighter than the brain).
- Video 5. Axial (horizontal) post-contrast bone window CT showing the fluid or soft tissue occupying the middle ear and mastoid.
- Video 6. Coronal (vertical, parallel to the face) CT of the temporal bones showing no tegmen (bone separating the brain from the ear) defect.
Watch the patient videos online at thehearingjournal.com.