麻豆传媒

Why did this 65-year-old man lose hearing in his left ear 6 months ago for no clear reason? That's the question facing Paul Merkus, MD, PhD, of the Amsterdam Public Health Research Institute in the Netherlands, and colleagues, in .

The patient's medical history included a heart attack, sleep apnea, and a hereditary cataract. He also had been diagnosed with Ménière disease, although he denied having any recent flare-ups.

He told clinicians he had no ear pain or fluid drainage, and had not experienced any other ear, nose, throat, or systemic symptoms. He reported use of atorvastatin (Lipitor) and acetylsalicylic acid, as well as drinking two glasses of wine daily; he did not smoke.

The clinicians noted that otoscopy of the left ear showed a yellow-whitish calcareous lobular mass located in the mesotympanum anterior to the malleus with an intact tympanic membrane. The lesion was hard and painful to the touch. Results of 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 about 60 dB HL. The tympanogram revealed a normal A-type curve with a normal to low middle ear compliance of 0.5 mm on the left side. CT imaging of the middle ear showed a heterogeneous hyperdense round mass of 5.5 mm in the left middle ear with a close relation 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 team said.

The team considered several differential diagnoses, including osteoma, cholesteatoma, and tympanosclerosis, before they settled on the diagnosis of tophaceous gout.

Discussion

Findings of otoscopy and CT imaging in this patient with tophaceous gout were "characteristic of an for 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 tissue or peripheral joints. When these macroscopic depositions (i.e., tophi) occur in the head and neck, they may affect the auricular helix, nasal bridge, larynx, and cricoarytenoid, as well as the temporomandibular and sternoclavicular joints. The risk of developing tophi is increased in people with obesity, high blood pressure, and those who use medications such as acetylsalicylates and diuretics. Lifestyle factors associated with increased risk of tophi include alcohol use, and a diet rich in meat, fish, and fructose.

Because it is so rare and presented without the characteristic clinical manifestations of gout or hyperuricemia in this patient, the authors noted that "tophaceous gout in the middle ear is often misidentified as osteoma, cholesteatoma, or tympanosclerosis."

"This emphasizes the importance of considering the diagnosis of a tophus in patients with conductive hearing loss and a mass in the middle ear," they added.

Merkus and colleagues outlined a series of diagnostic features to watch for:

• Otoscopy will reveal a lobular and white mass, which is caused by the accumulation of crystals in the tophus, and helps differentiate a tophus from osteoma and tympanosclerosis, in which the mass is denser and more rounded
• A CT scan often shows a tophus as heterogeneously hyperdense (i.e., a semolina-like structure), while "an osteoma appears as a compact mass, and tympanosclerosis or cholesteatoma as a more homogenous mass"

While these two diagnostic measures were all that were required in this patient's case, they noted that MRI can also help differentiate tophi from cholesteatoma, which is T2 hyperintense.

While most patients with ear tophi have undergone surgical removal, 2020 guidelines from the recommend the use of urate-lowering therapy with a serum urate target of less than 0.36 mmol/L or less than 6 mg/dL, as well as 6-month use of an anti-inflammatory prophylaxis therapy, for all patients with tophaceous gout, the authors explained.

In a of gout, researchers recommended that "patients receiving urate-lowering medications should be treated concurrently with nonsteroidal anti-inflammatory drugs, colchicine, or low-dose corticosteroids to prevent flares. Treatment should continue for at least three months after uric acid levels fall below the target goal in those without tophi, and for six months in those with a history of tophi."

The 2020 guidelines also conditionally recommended continuing urate-lowering therapy indefinitely over stopping it in patients with symptoms, and tophi or joint damage.

Merkus and team reported that their patient made lifestyle adjustments but his hearing loss progressed and he returned for surgery. Surgeons employed a postauricular, transmeatal approach to excise a brittle mass from the tensor tympani, malleus, and incudostapedial joint. The chorda tympani remained intact, and they reconnected the incus and stapes using bone cement. After surgery, the air-bone gap had closed completely. Histological analysis showed crystals that confirmed the diagnosis of gout.

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