Middle ear, inner ear and temporal bone tumors - benign / nonneoplastic
Middle ear adenoma

Reviewer: Nat Pernick, M.D. (see Reviewers page)
Revised: 5 October 2018, last major update December 2006
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PubMed Search: Middle ear adenoma
Cite this page: Pernick, N. Middle ear adenoma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/earmiddleearadenoma.html. Accessed October 20th, 2018.
Definition / general
  • Rare, benign glandular neoplasm originating from middle ear mucosa
  • First described in 1976 (Laryngoscope 1976;86:1123, Clin Otolaryngol Allied Sci 1976;1:17)
  • Neuroendocrine and epithelial differentiation; also called carcinoid tumor or amphicrine tumor (Ultrastruct Pathol 2001;25:73)
  • Rosai believes they form a continuum with carcinoid tumor and could be considered adenocarcinoid tumors
  • No gender preference, usually 20's to 40's, but wide age range
  • Affects all sites in middle ear
  • Occasionally perforates tympanic membrane and extends into external auditory canal
  • Not associated with chronic otitis media or cholesteatoma
  • Excellent prognosis; rarely is locally aggressive, invades vital structures, has regional metastases (Laryngoscope 2005;115:1660) or causes death
Case reports
  • Complete surgical excision
  • Mastoidectomy may be necessary for large lesions
  • Recurs with inadequate excision
Gross description
  • Gray-white to red-brown, firm/rubbery masses
  • Relatively well circumscribed
  • Not encapsulated
  • No hemorrhage, mean 0.8 cm
Microscopic (histologic) description
  • Variable patterns (sheets, solid, trabecular, cystic, cribriform, glandular, NOT papillary) of glands or tubules composed of uniform single layer of cuboidal or columnar cells with variable eosinophilic cytoplasm and round/oval hyperchromatic nuclei, eccentric nucleoli (if present)
  • May appear plasmacytoid, may have significant pleomorphism
  • May produce PAS+ mucin
  • Sparse fibrous or myxoid stroma
  • No/rare mitotic figures, no necrosis
  • May have neuroendocrine differentiation morphologically and immunohistochemically
Microscopic (histologic) images

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Case of the Week #376:



Cytokeratin AE1/3

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Trabeculae and ribbons

Prominent glandular pattern

Fig 1-mucin; 2-CAM5.2+; 3-synaptophysin+

Positive stains
  • Keratin (90%), CK7 (90%), chromogranin (88%), CAM5.2 (81%), mucin (intraluminal), lysozyme, neuron specific enolase (50%), synaptophysin (31%), serotonin (25%), S100 (15%), CK20 (6%, focal)
Negative stains
  • Actin
Electron microscopy description
Electron microscopy images

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Neurosecretory granules

Differential diagnosis