Why did this 65 year old man lose hearing in his left ear 6 months ago for no clear reason? This is the question facing Paul Merkus, MD, PhD, of the Amsterdam Institute for Public Health Research in the Netherlands, and his colleagues, in JAMA Otorhinolaryngology–Head and Neck Surgery.
The patient’s medical history included heart attack, sleep apnea and hereditary cataract. He had also been diagnosed with Ménière’s disease, although he denied having had recent flare-ups.
He told clinicians he had no ear pain or fluid drainage and had no other systemic symptoms in the ear, nose, throat. He reported using atorvastatin (Lipitor) and acetylsalicylic acid, as well as drinking two glasses of wine a day; he didn’t smoke.
Clinicians noted that otoscopy of the left ear showed a whitish-yellow calcareous lobular mass located in the anterior malleus mesotympanum with an intact tympanic membrane. The lesion was hard and painful to the touch. The results of the otoscopic examination of the other ear were normal.
An audiometry test identified mixed hearing loss affecting the left ear – pure tone average was 110 dB HL and bone conduction levels were around 60 dB HL. The tympanogram revealed a normal type A curvature with normal to low middle ear compliance of 0.5 mm on the left side. Middle ear CT imaging showed a 5.5 mm heterogeneous hyperdense round mass in the left middle ear with a close relationship to the malleus, eardrum, and tegmen. There were no other abnormalities in the mastoid, ossicular chain, facial nerve canal or surrounding blood vessels, Merkus and his team said.
The team considered several differential diagnoses, including osteoma, cholesteatoma and tympanosclerosis, before deciding on the diagnosis of tophaceous gout.
Otoscopy and CT imaging findings in this patient with tophaceous gout were “characteristic of an infrequent cause of a common middle ear mass,” the authors noted. Otoscopy can identify tophaceous gout, and the condition should be considered when diagnosing middle ear masses.
This inflammatory joint disease is marked by deposits of monosodium urate crystals, which usually occur in subcutaneous tissues or peripheral joints. When these gross deposits (i.e., tophi) occur in the head and neck, they can affect the atrial helix, nasal bridge, larynx, and cricoarytenoid, as well as the temporomandibular joints and sternoclavicular. The risk of developing tophus is increased in people who are obese, have high blood pressure, and those who use medications such as acetylsalicylates and diuretics. Lifestyle factors associated with an increased risk of tophi include alcohol consumption and a diet high in meat, fish, and fructose.
Because it is so rare and presented without the characteristic clinical manifestations of gout or hyperuricaemia in this patient, the authors noted that “tophaceous gout in the middle ear is often misidentified as an osteoma, a cholesteatoma or tympanosclerosis”.
“This underscores the importance of considering the diagnosis of tophus in patients with conductive hearing loss and a mass in the middle ear,” they added.
Merkus and his colleagues described a series of diagnostic features to look out for:
- Otoscopy reveals a lobular, white mass, which is caused by the accumulation of crystals in the tophus, and helps differentiate tophus from osteoma and tympanosclerosis, in which the mass is denser and more rounded
- A CT scan often shows hyperdense tophus heterogeneously (i.e., semolina-like structure), while “an osteoma appears as a compact mass, and a tympanosclerosis or cholesteatoma as a more homogeneous mass”
While these two diagnostic measures were the only ones needed in this patient’s case, they noted that MRI can also help differentiate tophus from cholesteatoma, which is hyperintense on T2.
While most patients with atrial tophi have undergone surgical removal, the 2020 American College of Rheumatology guidelines recommend the use of urate-lowering therapy with a target serum uric acid level below 0.36 mmol/L or less than 6 mg/dL, as well as 6-month use of anti-inflammatory prophylactic therapy, for all patients with tophaceous gout, the authors explained.
In a review of diagnosis, treatment, and prevention of gout, researchers recommended that “patients receiving urate-lowering drugs be treated concurrently with nonsteroidal anti-inflammatory drugs, colchicine, or low-dose corticosteroids to prevent flare-ups. Treatment should continue for at least three months after uric acid levels have fallen below the target range in people without tophi, and for six months in those with a history of tophi.
The 2020 guidelines also conditionally recommended continuing urate-lowering therapy indefinitely rather than stopping it in patients with symptoms, tophus, or joint damage.
Merkus and his team reported that their patient made lifestyle changes, but his hearing loss progressed and he returned for surgery. Surgeons used a postauricular and transmeatal approach to excise a fragile mass from the tensor tympani, malleum, and incudostapedial joint. The chorda eardrum remained intact and they reconnected the anvil and stapes using bone cement. After the surgery, the air-bone gap had completely closed. Histological analysis showed crystals which confirmed the diagnosis of gout.
The authors have reported no conflicts of interest.