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Ear Pathology Online

Pathology of Middle Ear Adenoma ; Neuroendocrine Adenoma of the Middle Ear and Carcinoid Tumour

Dr Sampurna Roy MD 


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Middle ear adenoma ( MEA) originating from the epithelium of the middle ear was first described by Hyams and Michaels in 1976.

The terms adenoma and carcinoid tumour of the middle ear can be used as synonyms, with the WHO favouring the term middle ear adenoma (MEA). 

These rare tumours show epithelial and neuroendocrine differentiations.

In 2009, Saliba and Evrard proposed a classification according to immunohistochemistry (+/−) and metastasis (+/−).

When both are negative, the tumour is described as an MEA.

The most common type shows positive immunohistochemistry and no metastasis and is described as a neuroendocrine adenoma of the middle ear.

The rarest finding is of a tumour with both positive immunohistochemistry and metastasis/carcinoid syndrome and is described as a carcinoid tumour of the middle ear.

Currently, the classification by Saliba et al. is the most widespread and includes (in order of prevalence) neuroendocrine adenomas, adenomas, and carcinoid tumours according to immunohistochemical markers and metastasis.

The tumours are composed of two types of cells: Exocrine and neuroendocrine in which neuroendocrine granules and sometimes neuropeptides (chromogranin, synaptophysin, serotonin, and pancreatic polypeptide) are detected.

Clinically, the patient often presents with deafness.

The tympanic membrane is usually nomal.

The lesion is confined to the middle air cleft with involvement sometimes of the mastoid air spaces.

Macroscopic features - The tumour appears white gray or reddish brown during operation.

The tumour seems to easily peel away from the walls of the surrounding middle ear.

Microscopically, all tumours are unencapsulated.

Architectural patterns include glandular, trabecular, solid, and infiltrative.

The small glands have a "back to back" appearance. 

The cells are predominantly composed of cuboidal-to-columnar cells with indistinct cytoplasmic borders.

The cytoplasm is eosinophilic and homogenous to finely granular.

The nuclei is round to oval with minimal pleomorphism.

The chromatin display a "salt-and-pepper" pattern consistent with a neuroendocrine origin. 

No myoepithelial layer is seen.

PAS and alcian blue stains may reveal mucoprotein secretion in the gland lumina and in the cytoplasm of the tumour cells.

Immunohistochemistry reveals that the tumour is cytokeratin, pancreatic polypeptide and chromogranin-positive, with a lesser number of tumours proving to be neuron-specific-enolase (NSE), synaptophysin, serotonin and S-100 protein-positive. 

Differential diagnosis: 

Important distinction to be made with adenoma of middle ear is from adenocarcinoma.

Middle ear adenomas are benign, and most tumours do not recur.

Most adenocarcinomas are metastatic and show destructive features clinically and on imaging.


Further reading

Middle ear adenoma: case report and discussion.

Neuroendocrine adenoma of the middle ear (NAME) mimicking as chronic otitis media with an episode of facial nerve palsy.

Neuroendocrine adenoma of the middle ear (NAME).

Middle ear glandular neoplasms: adenoma, carcinoma or adenoma with neuroendocrine differentiation: a case series.

Middle ear adenoma: case report and discussion.

"Neuroendocrine adenoma of the middle ear with the history of otitis media and carcinoma of the cheek: a case report".

Middle ear adenoma.

Middle ear adenoma is an amphicrine tumor: why call it adenoma?

Recurrent neuroendocrine adenoma of the middle ear: a case report.

Middle ear adenoma with neuroendocrine differentiation: relate of two cases and literature review.

Neuroendocrine adenoma of the middle ear.

'Neuroendocrine' middle ear adenomas: consistent expression of the transcription factor ISL1 further supports their neuroendocrine derivation.

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Dr Sampurna Roy  MD

Consultant  Histopathologist (Kolkata - India)






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