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Pathology of Papilloma of the Ear

Dr Sampurna Roy MD


Dermatopathology Quiz Case 216

Diagnosis: Squamous Papilloma of the Ear

Dermatopathology Quiz Case 217

Diagnosis: Inverted papilloma (Schneiderian-type papilloma) of the Ear


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Squamous papilloma:

Squamous papillomas are benign tumours which are commonly located in the  the skin, oral mucosa, upper respiratory tract, upper digestive tract and genital organs and occasionally in the external and middle ear.

Review of literature showed that out of all benign tumours of the ear reported so far, up to 80% are papillomas. More than 90% of these are located in the external auditory canal.

Human papilloma viruses are found to be the main causative agents of squamous papillomas of  external auditory canal.

Malignant transformation of external ear papilloma have been reported.

These are usually  solitary lesions. The tumour has a low risk of bony destruction. It grows slowly and can cause a mechanical obstruction of the external auditory canal. The lesion can cause pressure necrosis of the adjacent bone and deafness.

Histologically, the tumour is covered by stratified  squamous. They are characterized by papillomatosis , hyperkeratosis, parakeratosis, acanthosis, infrequent mitosis and rare nuclear atypia. Squamous cells with clear cytoplasm, dense dark nuclei and occasionally bi-nuclei are called koilocytic cells, which indicate an infection of the cells by HPV.

External ear canal papillomas should be distinguished from other skin lesions including an irritated seborrheic keratosis , carcinoma in situ and invasive SCC  , cholesteatoma , skin appendage, and/or other soft tissue neoplasms. However, unlike these lesions, in papillomas there is no glandular pattern, and the cytomorphologic features seen in adenomas. Immunohistochemistry for epithelial markers, such as cytokeratin can highlight a papilloma, rather than a neuroma, since the latter is negative for cytokeratin but is positive for S100 protein.

The occurrence of middle ear squamous papilloma is rare. It is usually associated with sinonasal pathology.

Inverted papilloma (Schneiderian-type papilloma):

Inverted papilloma (Schneiderian-type papilloma), is a benign but locally aggressive sinonasal tumour that rarely involves the middle ear or temporal bone. 

HPV types 6, 11, 16 and 18 are the most common causative agents associated with Inverted papilloma and types 16 and 18 are more commonly associated with malignancy.

Microscopically, inverted papilloma is characterized by the digitiform proliferation of squamous epithelium into the underlying connective tissue stroma.

Direct extension of the sinonasal tumour through the eustachian tube may represent the pathologic mechanism involved in the development of inverting papilloma involving the middle ear and temporal bone.

Literature reports indicate that inverted papillomas of the middle ear and mastoid differ pathogenically and epidemiologically from sinonasal inverted papillomas.

Recurrence rates and association with squamous cell carcinoma are higher in Schneiderian-type papillomas of the middle ear than in inverted papillomas of the nose and paranasal sinuses.

Long-term follow-up after removal of inverted papilloma of the middle ear and mastoid is mandatory. 


The papilloma may be either exophytic (everted), inverted or oncocytic.

Successful management of these tumours requires an aggressive surgical resection.

Adjuvant radiation therapy is recommended in patients with malignant changes.

Further reading

Multifocal inverted papillomas in the head and neck.

Papillomas of the External Ear Canal: Report of Ten cases in Chinese Patients with HPV In Situ Hybridization

Middle ear squamous papilloma: A report of four cases analyzed by HPV and EBV in situ hybridization

Squamous papilloma in the external auditory canal

Inverting papilloma of the temporal bone: case report and meta-analysis of risk factors.

Schneiderian papilloma of the temporal bone.

Inverting papilloma of the temporal bone: case report and meta-analysis of risk factors.

Sinonasal inverted papilloma with malignant transformation in the middle ear: a multicentric origin?

Middle ear squamous papilloma: report of a case and literature review.

Primary inverted papilloma of the middle ear and mastoid.

Inverting papilloma of the temporal bone.

Clinical and molecular pathology of aggressive Schneiderian papilloma involving the temporal bone.

Schneiderian-type mucosal papillomas of the middle ear and mastoid.

Dissemination of squamous papilloma by surgical manipulation: a case report.


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Dr Sampurna Roy  MD

Consultant  Histopathologist (Kolkata - India)







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