Osteomas Of the External Ear

Introduction

Osteomas are benign tumors of the ear. But it needs to be differentiated from the exostosis of the ear canal as it appears the same. Osteoma is a tumor that obstructs the ear canal whereas exostosis is the overgrowth of the external auditory canal’s compact bone. Both osteomas and exostoses may result in hearing loss.

What Is Osteoma of the External Ear?

Osteomas are bony tumors that generally occur in the external auditory canal (EAC), mastoid cortex, bones of the face, and mandible (lower jaw). Osteoma of the EAC may obstruct the ear canal leading to hearing loss. They are non-invasive and benign tumors and may cause many symptoms. It occurs most commonly in children and adults. It affects males more than females.

These tumors are made up of mature bone and slow-growing, and unilateral. The most common sites are the head and neck region and the fronto ethmoidal region. Tumors occurring in the temporal region are rare. But osteomas may occur in the temporal region, especially in EAC. It can also occur in other parts of the temporal bone, such as the middle ear space. Osteomas in this region cause facial nerve dysfunction as the facial nerve is situated here. Osteoma is rare in the temporal bone, with the highest predisposition to EAC. EAC osteomas have a low recurrence rate. They do not turn to malignancy (cancer).

What Are the Causes of Osteoma of the External Ear?

The exact cause of osteoma of the external ear is not known. Some of the factors may cause osteoma. They are:

• Injury or trauma.

• Inflammation.

• Hormones.

• Infection.

• Developmental defects.

• Genetic disorders such as cystic fibrosis and Down syndrome.

• Persistent embryonic periosteum.

• Muscle traction.

• Gardner’s syndrome (colon polyps that may become colon cancer).

Some studies have reported that very few surfers and swimmers developed EAC osteoma.

What Are the Symptoms of Osteoma of the External Ear?

These bony tumors obstruct the ear canal and cause other symptoms.

• Loss of hearing.

• Ear fullness.

• Tinnitus (ringing in the ears).

• Pain in the ear.

• Vertigo (dizziness).

• Trigeminal neuralgia.

Osteomas and exostosis of EAC should be differentiated as these two appear similar in clinical symptoms.

What Are the Complications of Osteoma of the External Ear?

There may be a development of cholesteatoma along with osteoma of EAC. This may be due to impaired epithelial migration. Recurrent otitis externa and hearing loss may also be caused.

How to Diagnose Osteoma of the External Ear?

Osteoma and exostosis share similar symptoms and should be differentiated by conducting many tests.

• Physical Examination: After physical examination, one can observe a white pearly bony outgrowth at the junction of bony cartilage in the external ear canal.

• Radiograph examination: Radiographically, osteomas showed a hyperdense mass, single, pedunculated, unilateral developing from tempanomastoid and tympanosquamous suture line. But exostosis looks like a hyperdense mass protruding from the internal auditory canal, which is multiple, bilateral, smooth-bordered, having a broad base without deep extension.

• CT(Computed Tomography): Computed tomography is done to know the detailed picture, and scan, of areas inside.

• MRI (Magnetic Resonance Imaging): It may show the high intensity of bone marrow within the tumor.

• Histological findings: Histologically, EAC osteomas contain lamellar bone that has minimal osteocytes, surrounded by fibrovascular channels. But exostosis contains subperiosteal bone, which has parallel and concentric layers and abundant osteocytes.

• The presence or absence of fibrovascular channels is the distinguishing feature of osteoma and exostosis in histological examination. A recent study reported that even exostoses will have fibrovascular channels, so both cannot be differentiated histologically.

What Is the Treatment for Osteoma of the External Ear?

Osteomas are asymptomatic, and they are found during the evaluation of other conditions. Most of them do not require treatment. When excessive ear wax buildup is present, cleaning will be done to remove the ear wax. Treatment includes:

• Periodic observations of the lesion should be done.

• In case of any complications or symptomatic lesions, a surgical approach is used to remove the tumor.

• The surgical approach is done through the external auditory meatus. The prognosis after surgery is excellent. Generally, osteomas are removed microscopically through transcanal, postauricular, and endaural approaches. The small lesion located lateral to the isthmus can be directly removed by transcanal approach. Another two approaches may be used for lesions that are located medially and have a broad base.

• TEES (trans canal endoscopic ear surgery), a procedure to remove osteomas of EAC can be used. This non-invasive method provides a wider-angled surgical view and increases tissue preservation. This does not cause any complications after the removal of the lesion with no reoccurrence. It minimizes the time taken for the procedure.

What Is the Differential Diagnosis for Osteoma of the External Ear?

In the case of a differential diagnosis of ear canal osteoma, both benign and malignant conditions should be considered.

• Squamous Cell Carcinoma: It is the most malignant tumor of the EAC.

• Basal Cell Carcinoma (nodular): It is also a skin cancer that starts in the basal cells.

• Melanoma: It is a tumor of melanin-forming cells, especially a malignant tumor that is associated with skin cancer.

• Exostoses: These are most common than osteomas. They are multiple, bilateral, and common among individuals exposed to cold water and wind. These are protrusions that are sessile.

• Benign Polyp: It is a soft, fleshy mass that is circumscribed and associated with cholesteatoma or chronic ear infections.

Other common ear lesions of the ear canal are adenoma, lipoma, fibroma, chondroma, keratoacanthoma, and salivary gland tumors ( benign and malignant). They can be differentiated by performing a biopsy.

Conclusion

Osteomas of the external ear are rare in occurrence. The ear is an important organ of the body. Any slight changes in the ear may lead to discomfort and affect the quality of life of an individual. Hence it becomes important to know about the condition and its causes, symptoms, diagnosis and treatments, and complications. This helps an individual to seek help from a healthcare provider. Early diagnosis help in achieving effective treatment. This, in turn, provides a chance to lead a good quality of life.