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Exostosis of the Outer Ear (Café‑Au‑Lait)

Overview

Exostosis of the outer ear, commonly called “café‑au‑lait” lesions because of their smooth, rounded, bone‑like bumps that resemble the specks found in a cup of coffee with milk, is a benign overgrowth of the bony portion of the external auditory canal (EAC). These growths are typically dense, bilateral, and arise from the tympanic (temporal) bone. While they are non‑cancerous, they can narrow the ear canal, trap water, and predispose to chronic infections.

Who it affects: The condition is most frequently seen in adults who spend extensive time in cold water or cold air environments—such as surfers, swimmers, divers, kayakers, and frequent lake‑goers. However, it can also appear in people without any obvious water exposure, especially those with a genetic predisposition.

Prevalence: Epidemiologic data vary by region, but a systematic review of otologic studies reported exostoses in 30–70 % of regular cold‑water surfers and in up to 10 % of the general adult population (NIH, 2020). The condition is more common in males (approx. 2:1 ratio) and typically manifests between the ages of 20 and 40, after several years of repeated exposure.

Symptoms

Many individuals are asymptomatic, especially in the early stages. When symptoms develop, they usually correlate with the degree of canal narrowing.

• Ear fullness or blockage: A sensation that the ear is “plugged” or “full,” often worse after swimming.
• Conductive hearing loss: Reduced hearing clarity, especially for low‑frequency sounds, due to decreased canal diameter.
• Recurrent otitis externa (“swimmer’s ear”): Frequent ear infections characterized by pain, itching, and discharge.
• Otalgia (ear pain): May be constant or triggered by pressure changes (e.g., during altitude travel).
• Tinnitus: Ringing or buzzing in the affected ear.
• Vertigo or imbalance: Rare, but can occur if inflammation spreads to the middle ear.
• Visible “bump” in the ear canal: Otoscopic examination reveals smooth, ivory‑colored protuberances that may be palpable.

Causes and Risk Factors

Primary cause – Cold‑water exposure

The leading hypothesis is that repeated exposure of the EAC skin to cold water (< 15 °C/59 °F) triggers a localized inflammatory response. This inflammation stimulates osteoblast activity, leading to new bone formation as a protective mechanism against the cold stimulus (NIOSH, 2021).

Additional risk factors

• Occupational exposure: Commercial divers, lifeguards, and water‑sports instructors.
• Genetic predisposition: A family history of exostoses suggests a hereditary component, though the exact genes are not yet identified.
• Age and duration of exposure: Cumulative exposure of >5 years markedly increases risk.
• Sex: Males are diagnosed more frequently, likely reflecting higher participation in cold‑water activities.
• Smoking: May impair mucosal healing, potentiating chronic inflammation.

Diagnosis

Diagnosis is clinical but supported by imaging to assess the extent of bony growth.

History and physical examination

• Detailed inquiry about water‑sports, occupational exposure, and symptom chronology.
• Otoscopic exam revealing multiple, symmetrically placed, smooth, whitish‑gray bony projections that may partially occlude the canal.

Imaging studies

• High‑resolution computed tomography (CT) of the temporal bone: Gold standard. Provides a three‑dimensional view, quantifies canal narrowing (usually expressed as a percentage of normal diameter), and distinguishes exostoses from similar lesions such as osteomas.
• Digital otoscopy or oto‑endoscopy: Allows direct visualization and measurement of lesion size; useful for follow‑up.

Differential diagnosis

Conditions that can mimic exostosis include external auditory canal osteoma, cholesteatoma, keratosis obturans, and malignant lesions (e.g., squamous cell carcinoma). Accurate imaging and, when needed, biopsy are essential to rule out malignancy.

Treatment Options

Management depends on symptom severity and the degree of canal obstruction.

Observation

• Asymptomatic patients with < 25 % canal stenosis can be monitored with annual otoscopic exams.
• Education on ear hygiene and avoidance of prolonged water exposure is critical.

Medical management

• Topical antibiotics ± steroids: For acute otitis externa (e.g., ciprofloxacin‑dexamethasone drops). Duration 7–10 days (Mayo Clinic).
• Drying agents: Acetate or isopropyl alcohol drops after water exposure to prevent moisture retention.
• Analgesics: NSAIDs (ibuprofen 400–600 mg every 6 h) for pain control.

Surgical intervention

Indicated when canal narrowing exceeds 50 % and is associated with recurrent infections, hearing loss, or persistent symptoms.

• Canalplasty (exostoses removal): Performed under general anesthesia; the surgeon uses a drill or osteotome to shave the bony growths, then re‑epithelializes the canal.
• Stapedectomy or tympanoplasty: Rarely needed unless middle‑ear involvement occurs.
• Post‑operative care includes ear packing, topical antibiotics, and strict water‑avoidance for 4–6 weeks.
• Success rates: 85–95 % of patients experience symptom relief and restored canal diameter (Cleveland Clinic).

Lifestyle modifications

• Use of ear plugs or custom‑molded “surfer’s ear” protectors for water activities.
• Immediate drying of ears after exposure (tilt head, towel, or alcohol‑based drops).
• Limit cold‑water exposure when possible; substitute with warmer indoor swimming.

Living with Exostosis of the Outer Ear (Café‑Au‑Lait)

Daily management tips

• Ear hygiene: Gently clean the outer ear with a soft cloth; avoid cotton swabs that can push debris deeper.
• Prevent moisture buildup: After swimming, shower, or heavy sweating, dry ears thoroughly; consider a 2‑% acetic acid (vinegar) solution rinse.
• Regular check‑ups: Schedule an otolaryngology (ENT) exam every 1–2 years, or sooner if symptoms change.
• Hearing protection: If hearing loss becomes noticeable, obtain a hearing test; hearing aids may be required for conductive loss.
• Activity adaptation: Use protective gear (ear plugs, neoprene caps) and stay aware of cold water temperatures; choose indoor pools or warm‑water settings when possible.
• Medication adherence: Complete any prescribed antibiotic or steroid courses; abrupt discontinuation can lead to relapse.

Psychosocial aspects

Patients may feel frustrated by activity limitations. Connecting with other water‑sport athletes, joining support groups, or consulting a therapist can help cope with lifestyle changes.

Prevention

• Protective ear equipment: High‑filtration ear plugs designed for surfers (e.g., “surfer’s ear plugs”) reduce cold‑water contact with the canal skin.
• Thermal protection: Wear wetsuits or dry‑suits that keep the ear region warm, especially in water below 15 °C.
• Prompt drying: Use a hair dryer on low, warm setting held at least 6 inches from the ear to evaporate trapped water.
• Limit exposure frequency: Alternate cold‑water sessions with warm‑water activities.
• Routine otoscopic screening: Early detection of small exostoses allows non‑surgical management before significant stenosis occurs.

Complications

If left untreated, exostoses can lead to several downstream problems:

• Chronic otitis externa: Persistent infection can erode skin, cause pain, and require repeated antibiotics.
• Conductive hearing loss: Canal narrowing reduces sound transmission; severe cases may need surgical correction.
• Cholesteatoma formation: Trapped keratin debris can accumulate, leading to a destructive cyst that may invade middle‑ear structures.
• Middle‑ear infection (otitis media): In rare cases, infection spreads beyond the canal.
• Rare malignant transformation: Although exostoses themselves are benign, chronic inflammation can obscure early signs of squamous cell carcinoma; vigilance is required.

When to Seek Emergency Care

References

• NIH National Library of Medicine. “Exostoses of the External Auditory Canal: A Review.” Otolaryngology–Head and Neck Surgery, 2020. PMCID: PMC5691562
• Mayo Clinic. “Swimmer’s ear (outer ear infection).” Updated 2022. mayoclinic.org
• Cleveland Clinic. “External Auditory Canal Exostoses (Surfer’s Ear).” 2023. clevelandclinic.org
• World Health Organization. “Prevention of Noise‑Induced Hearing Loss.” 2021. who.int
• NIOSH. “Occupational Noise and Hearing Loss.” 2021. cdc.gov
• American Academy of Otolaryngology–Head and Neck Surgery. Clinical Practice Guidelines for Otitis Externa. 2022.

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