An 84-year-old man presented with pain in his right ear with yellow discharge, bleeding, aural pressure, and hearing loss. The pain, which had been going on for a month, was exacerbated by chewing, and disturbed his sleep. He denied experiencing any dizziness or tinnitus, and had no symptoms in his left ear. On physical exam, a mass with copious yellow debris was visualized in the right auditory canal, obstructing the tympanic membrane (Fig. 1). The otoscopic evaluation of his left ear, as well as the examination of the remainder of his head and neck, had normal results. His audiogram showed severe conductive hearing loss.
Diagnosis: Granulation Tissue from Post-inflammatory Atresia
A mass in the ear canal, especially in an elderly patient, should be considered malignant until proven otherwise. Characteristics suggestive of malignancy include pain, bleeding, numbness, or weakness of the face on the affected side, changes in taste on the same side, a history of chronic otitis externa, and a history of sun exposure or skin cancer on the auricle or scalp.
Malignancies in the ear canal are rare, but among those that do occur, the most common types are squamous cell carcinomas (SCC) and basal cell carcinomas (BCC), with SCC representing about 80 percent of malignant tumors. These are cancers of the skin that often start on the outer ear or in the skin overlying the external auditory canal (EAC). Melanomas can also develop within the external auditory canal.
The next most common tumor, the cystic adenocarcinoma, is comparatively much less common, and makes up only about five percent of EAC malignancies. Cystic adenocarcinomas, also called adenoid cystic carcinomas, are tumors of the glands that produce cerumen. Finally, tumors from nearby structures such as the parotid gland can expand to grow into the auditory canals via the foramen tympanicum (also called the foramen of Huschke) or the fissures of Santorini. The foramen tympanicum is a defect in ossification that results in an opening from the EAC to the infratemporal fossa, and is associated with fistulas between the EAC and parotid gland. The fissures of Santorini is the name for the gaps in the cartilage lining the anterior portion of the EAC. These two areas represent ways not only for outlying malignancies to infiltrate the ear canal but also for otologic malignancies to spread and metastasize beyond the ear.
Benign masses in the EAC are fortunately more common than malignancies. Exostosis, osteomas, and adenomas (not to be confused with cystic adenocarcinomas) are among the most likely to be found. Skin lesions such as seborrheic keratoses can also occur in the ear canal or on the auricle. Individuals may also develop cholesteatomas or granulation tissue in the external auditory canal. Cholesteatomas or chronic otitis media with perforation or a tympanostomy tube can cause an intense inflammatory reaction in the middle ear or mastoid with a large granulation tissue coming from the middle ear and extending into the ear canal. In rare cases, osteonecrosis can be caused by radiation therapy, or bisphosphonates (medications to treat osteoporosis) can cause granulation and appear as a mass.
A biopsy will give a more definitive answer as to whether a mass is malignant; however, before obtaining a biopsy, it may be necessary to obtain imaging to ensure that the mass does not represent anomalous blood vessels (e.g., the carotid artery or jugular vein) or a glomus tumor, both of which will bleed extensively if biopsied. Typically, an MRI of the internal auditory canals with gadolinium and a CT scan of the temporal bones are sufficient. The MRI is able to show better contrast of soft tissue structures and reveal any vascularity of the mass as well as any extension into nearby soft tissue structures, such as the dura, facial nerve, parotid gland, temporo-mandibular joint, and mastoid. The CT scan, on the other hand, is best at showing the bony anatomy and revealing any erosion of the bone and potential invasion into the middle ear.
Another consideration prior to biopsy is how large or deep of a biopsy is needed. Both benign and malignant processes can trigger inflammation, which can result in a layer of granulation adhering over the mass itself. A mass may even have normal skin overlying it. If suspicion for malignancy is high, a larger or deeper biopsy should be done to rule out an underlying malignancy with overlying inflammatory or squamous epithelium. We have seen this on a few occasions where the initial biopsy was negative but a subsequent larger biopsy (removing more skin) was positive for carcinoma. This can occur because a small biopsy specimen can get crushed by the alligator or otologic cup forceps, changing its appearance on histology. Sometimes, the pathologist will report the cancer as carcinoma in situ in a small biopsy. This can occur since an invasive cancer diagnosis requires invasion of the basement membrane, which is the membrane at the base of the skin overlying the periosteum. However, a superficial or small biopsy specimen may not appear to show invasion, creating a seemingly limited superficial carcinoma when the tumor can be deeper elsewhere.
The patient's CT scan showed that the mass in the EAC had no erosion of the surrounding bone (Figs. 2 and 3). Although the lack of erosion was a positive sign, it did not rule out malignancy since cancers must breach the periosteum first to invade bone. The results of this process are not evident on CT scan until more significant changes to the bone have occurred. On MRI, the mass displayed some vascularity (Figs. 4 and 5) but appeared to be limited to the EAC and did not extend to the surrounding soft tissue. This, too, was a positive sign; however, it did not rule out malignancy either since some tumors can be exophytic and will grow upward and outward as opposed to eroding into deeper tissues.
Having ruled out a highly vascular mass and vascular anomaly, we took a biopsy, which showed only granulation tissue and no evidence of malignancy. Due to our high suspicion, we re-biopsied the canal mass with larger forceps and obtained deeper biopsies that also resulted in a granulation tissue diagnosis. The patient was scheduled for surgery to remove the mass, and upon removal, it was found that the patient likely suffered from chronic stenosing otitis externa and was in the final stages of post-inflammatory atresia of the ear canal. This condition is thought to be idiopathic (unknown cause) but possibly related to lichen planus. It causes circumferential loss of squamous epithelium and replacement with granulation, which can result in hypertrophy and cause complete blockage of the ear canal. The best treatment option involves removing the granulation and scar tissue and performing a split-thickness skin graft procedure. The patient successfully underwent surgery with closure of the air-bone gap.
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 showing a mass in the ear canal but no bony erosion into the mastoid or the anterior ear canal.
- Video 2. Coronal (vertical, parallel to the face) CT showing the mass with some opacification of the mastoid and the epitympanum.
- Video 3. Sagittal (vertical, parallel to the ear) CT showing the canal to be fully intact.
- Video 4. Axial (horizontal) T1 post-gadolinium MRI showing the mass in the ear canal and no extension into the mastoid or parotid gland.
- Video 5. Coronal (vertical, parallel to the face) T1 post-gadolinium MRI showing that the mass did not extend intracranially.
- Video 6. Axial (horizontal) DWI MRI showing no cholesteatoma.Watch the patient videos online at thehearingjournal.com.
Watch the patient videos online at thehearingjournal.com.