Ear Tumors: Types, Classification, Symptoms, Diagnosis, Treatment

Ear tumors comprise a diverse group of neoplasms that can be both benign and malignant (ear cancer). They are localized in various parts of the ear: outer, middle, or inner. Depending on the tumor origin and nature, its symptoms and treatment approaches may vary. This article reviews the most commonly encountered ear tumors.

Definitions of Ear Tumors

• Atheroma of the earlobe is a benign soft tissue lesion located within the earlobe. It is a sebaceous gland cyst.
• Cutaneous horn is a keratotic skin lesion of the auricle. It is usually benign, but in some cases it may be associated with premalignant changes.
• Basal cell carcinoma (BCC) of the auricle is a malignant skin tumor arising from the basal layer of the epidermis. It is the most common form of skin cancer.
• Squamous cell carcinoma (SCC) of the auricle is a malignant tumor arising from epidermal keratinocytes. It is the second most common type of skin cancer after BCC.
• Glomus tumor, or paraganglioma, is a benign tumor of the tympanic cavity. It is located in the region of the tympanic plexus or the superior bulb of the internal jugular vein.
• Congenital cholesteatoma is an abnormal tumor-like growth in the middle ear behind an intact tympanic membrane. It develops prenatally and is not associated with a preceding inflammatory process.
• Vestibular schwannoma, also known as acoustic neuroma, is a benign tumor arising from the nerve sheath cells (Schwann cells) of the vestibulocochlear nerve.

Classification

Formations of the outer ear:

• Atheroma of the earlobe;
• Cutaneous horn of the auricle;
• basal cell carcinoma of the auricle;
• squamous Cell Carcinoma of the Auricle.

Formations of the middle ear:

• glomus Tumor (Paraganglioma);
• congenital cholesteatoma.

Formations of the inner ear:

• Vestibular schwannoma.

Etiology

Atheroma of the earlobe develops when the duct of a sebaceous gland becomes obstructed. Predisposing factors include narrow excretory ducts, increased sebum production, endocrine dysfunction, and inadequate local skin hygiene. If infection occurs, the cyst may suppurate.

The exact causes of cutaneous horn have not been fully established. The lesion occurs in older adults and is more common in areas exposed to repeated friction. Prolonged exposure to ultraviolet (UV) radiation, human papillomavirus (HPV) infection, and a family history of cutaneous horn in first-degree relatives are considered the main risk factors.

Basal cell carcinoma (BCC) of the auricle is the most common form of skin cancer and one of the most common cancers overall. Excessive exposure to UV radiation is the primary risk factor for BCC. People with fair skin and those with prolonged sun exposure, such as outdoor workers, have a higher risk of developing this tumor.

Squamous cell carcinoma (SCC) is also associated with excessive UV exposure. Malignant transformation more often develops in pathologically altered tissues, such as actinic keratosis, chronic ulcers, or scars.

The most common tumor of the middle ear is nonchromaffin paraganglioma, commonly referred to as glomus tumor. Its cause remains unknown. In most cases, the tumor occurs sporadically. However, a genetic predisposition has been identified in approximately 10% of cases.

The exact cause of congenital cholesteatoma has not been established. Several theories of its origin have been proposed. Most are based on abnormal cell migration during embryogenesis. This process may occur before the tympanic ring has fully formed. Alternatively, if the tympanic membrane has already formed, cells may migrate through microperforations caused by an intrauterine infection. These microperforations later heal after birth. Another theory suggests that the amniotic fluid within the tympanic cavity of newborns contains squamous cells that produce keratin and serve as a matrix for cholesteatoma.

Vestibular schwannoma, also known as acoustic neuroma, is a slow-growing, well-encapsulated tumor composed exclusively of Schwann cells of the vestibulocochlear nerve. Incidence and etiology are unknown. The tumor is more common in patients with neurofibromatosis type 2.

Anatomy

Atheroma of Earlobe

An atheroma of the earlobe is a small, spherical, encapsulated lesion located within the thickness of the earlobe. Its cavity is filled with whitish sebaceous debris. In cases of a secondary infection, the atheroma may suppurate and increase significantly in size. The overlying skin becomes red and inflamed, and the lesion may be tender and fluctuant on palpation.

Cutaneous Horn

A cutaneous horn is a dense, flesh-colored growth with well-defined borders that protrudes above the skin surface. It arises from the epidermis and consists of compact keratin formed by keratinizing epidermal cells. Ulceration is not typical, and the auricular cartilage remains intact. The lesion is usually 1–2 cm long, and its length exceeds the diameter of its base. Slow growth and absence of metastasis to regional lymph nodes are characteristic.

Basal Cell Carcinoma of the Auricle

Several subtypes of BCC are distinguished:

• Nodular — a firm papule with rounded edges that protrudes above the skin surface; a small ulcer or crust may be present in the center;
• Superficial — a small erythematous, scaly, irregular plaque of varying shades;
• Ulcerative — a skin defect with undermined, irregular edges;
• Pigmented — a dark-colored plaque that protrudes above the skin surface;
• Morpheaform, or sclerosing — a flat, waxy, poorly defined plaque with prominent telangiectasia.

On microscopy, the tumor consists of epithelial cells with large hyperchromatic nuclei and scant cytoplasm. It arises from the basal layer of the epidermis.

Squamous Cell Carcinoma of the Auricle

SCC is characterized by atypical cells with intercellular desmosomes and varying degrees of keratinization. The tumor spreads into surrounding tissues, which is known as local invasion. Its clinical appearance is highly variable. Therefore, any abnormal skin lesion with poorly defined borders, uneven coloration, delayed healing, or bleeding should raise suspicion.

Paraganglioma

Paraganglioma is a neuroectodermal tumor that arises from the parasympathetic ganglia as a result of neural crest cell migration during embryogenesis. Women are affected 4–6 times more often than men.

Microscopy identifies neuroendocrine cells arranged in clusters with fibrous septa and supporting cells between them. The tumor is highly vascular and grows expansively. As it enlarges, it may compress adjacent cranial nerves, including the facial, glossopharyngeal, vagus, accessory, and trigeminal nerves.

On otoscopy, paraganglioma appears as a bright burgundy-red mass visible through the tympanic membrane. In some cases, it may protrude into the external auditory canal as a bleeding polyp. Its primary growth site is located on the medial wall of the tympanic cavity in the region of the tympanic plexus or in the bulb of the internal jugular vein. Malignant transformation is extremely rare and occurs in approximately 5% of cases. The presence of distant metastases is considered a sign of malignancy. Metastatic foci are usually found in the lungs, lymph nodes, liver, spine, ribs, and spleen.

Depending on location, four types of paraganglioma are distinguished:

• Type 1 — glomus tympanicum tumor limited to the tympanic cavity;
• Type 2 — glomus jugulare tumor that does not invade bone and is limited to the middle ear cavity and the jugular bulb;
• Type 3 — glomus jugulare tumor that invades the mastoid process of the temporal bone;
• Type 4 — glomus jugulare tumor that extends into the cranial cavity.

Congenital Cholesteatoma

Congenital cholesteatoma is a rare benign tumor-like lesion of the middle ear. It forms during fetal development and consists of keratin-producing skin cells, or keratinocytes. These cells continuously produce keratin. As keratin is shed, it accumulates and forms the matrix, or body, of the cholesteatoma. Cholesterol deposition contributes to the lesion’s characteristic pearly appearance. As the lesion grows and produces aggressive substances, it causes erosive destruction of the ossicular chain. This leads to conductive hearing loss. Typical otoscopy findings include a pearly mass behind an intact tympanic membrane, most often in the anterosuperior quadrant. The diagnosis of congenital cholesteatoma can be confirmed only if the tympanic membrane is intact and there is no history of middle ear inflammation or ear surgery.

Vestibular Schwannoma

Vestibular schwannoma most often arises from the superior portion of the vestibular nerve within the internal auditory canal.

Clinically, two forms of schwannoma are distinguished:

• medial;
• lateral.

Medial schwannomas are located in the cerebellopontine angle. Lateral schwannomas are located within the internal auditory canal. From the internal auditory canal, they may extend into the cranial cavity toward the cerebellopontine angle. As both forms enlarge, they may compress adjacent tissues, including cranial nerves, the cerebellum, and the brainstem.

Histologically, vestibular schwannoma is characterized by proliferation of spindle-shaped Schwann cells with indistinct borders and the presence of Verocay bodies. Verocay bodies are acellular areas surrounded by spindle-shaped nuclei. The tumor grows slowly and expansively, but it may reach a large size of > 2.5 cm. Metastasis is not typical.

Clinical Manifestations

An atheroma of the earlobe usually causes cosmetic concern rather than functional symptoms. If it suppurates, marked tenderness develops.

Another cosmetic defect is the cutaneous horn. It can be frequently traumatized as it protrudes significantly above the skin surface. Cases of cutaneous horn measuring 6–10 cm have been described in the literature.

BCC of the auricle is a slowly enlarging, translucent skin lesion with heterogeneous coloration and areas of ulceration. It rarely metastasizes. However, it shows marked local invasion and may cause significant cosmetic defects. Moreover, it has a high risk of recurrence.

SCC of the auricle appears as an erythematous, scaly plaque that protrudes above the skin surface. Ulceration is common. The lesion may itch and bleed. This tumor grows rapidly and has a high risk of metastasis. It may lead to fatal outcomes, particularly in advanced or metastatic disease. In recent years, there has been an increase in incidence. It occurs three times more often in men than in women. Patients with immunodeficiency have a worse prognosis, including organ and tissue transplant recipients receiving immunosuppressive therapy. Lesions larger than 2 cm in diameter, with invasion deeper than 2 mm, or located on the scalp, ears, or nose have a high risk of recurrence.

Paraganglioma of the tympanic plexus is characterized by hearing loss and pulsatile tinnitus on the affected side. Hearing loss is initially conductive. Later, a sensorineural component may develop, resulting in mixed hearing loss. When a glomus tumor is located in the region of the jugular bulb, cranial nerve palsy may occur because of jugular foramen involvement. The glossopharyngeal, vagus, and accessory nerves are most often affected. The hypoglossal nerve is affected less commonly. If the tumor extends into the cranial cavity, symptoms of brain or cerebellar involvement and facial nerve paresis may develop.

Congenital cholesteatoma can be asymptomatic for a long time. However, as the tumor enlarges, hearing loss, vestibular dysfunction, facial nerve paresis, or, in severe cases, intracranial complications may develop. These symptoms usually prompt patients to seek medical help.

Vestibular schwannoma is characterized by both general and local symptoms, which vary depending on the location of the tumor. Like congenital cholesteatoma, vestibular schwannoma can also remain asymptomatic for a long time. Local manifestations include compression of the vestibulocochlear nerve and associated unilateral sensorineural hearing loss. Other findings may include absence of the loudness recruitment phenomenon, absent stapedius acoustic reflex, tinnitus in the affected ear, and vestibular symptoms such as spontaneous nystagmus toward the unaffected ear and dizziness. Cerebellar compression is associated with dysdiadochokinesia and ataxia. Large tumors may cause increased intracranial pressure and projectile vomiting. Paresis of the facial, trigeminal, and abducens nerves may also occur.

Diagnosis

An atheroma of the earlobe is assessed clinically. However, because it may resemble other subcutaneous lesions (e.g., fibroma, lipoma), a definitive diagnosis is made based on the results of a histopathologic examination.

A cutaneous horn is evident upon physical examination. A detailed medical history can also be helpful to determine its origin.

To confirm BCC, a targeted biopsy is performed, followed by histopathologic examination.

For paraganglioma and cholesteatoma, otoscopy is the first-line examination. Then, to determine the exact location of paraganglioma and its vascular origin, high-resolution CT and gadolinium-enhanced MRI are performed. Diffusion-weighted MRI is used to visualize cholesteatoma. Before surgery for paraganglioma, angiography and embolization of tumor-feeding vessels are performed. In families with known paraganglioma, unaffected relatives may undergo genetic testing. This allows the disease to be detected at an early stage.

If vestibular schwannoma is suspected, a comprehensive audiologic evaluation is performed. It includes pure-tone and speech audiometry, as well as auditory evoked potential testing. Nystagmus assessment and vestibular testing are also performed. Gadolinium-enhanced MRI is used to determine the tumor location.

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Treatment

Atheromas should be removed surgically. It is important to dissect and remove the tumor capsule to prevent recurrence. If the lesion suppurates, it is incised and its contents are evacuated. A drain is placed, and an aseptic dressing is applied. Dressings are changed regularly until complete healing.

Precancerous lesions, such as cutaneous horn, and carcinomas are surgically excised with a margin of healthy tissue. If there are contraindications to surgery, radiation therapy is used.

Congenital cholesteatoma is removed surgically. If indicated, tympanoplasty can also be performed.

The preferred treatment for paraganglioma and vestibular schwannoma is total surgical removal. If it is not an option, then partial resection followed by radiation therapy may be performed, including Gamma Knife radiosurgery. Radiation therapy alone can be used in patients with contraindications to surgery or in the elderly. A “watch and wait” approach is usually recommended for small (~1 cm) and asymptomatic vestibular schwannomas.

Please note that histopathological examination of all removed tissues is mandatory.