Abstract
Neuroendocrine adenoma of the middle ear has been described in literature as middle ear adenoma with neuroendocrine differentiation or carcinoid tumor. While there have been several case reports describing imaging features of carcinoid tumors of the ear and middle ear adenomas, in our literature review, we have not found a single case where bone formation is described as a prominent radiological feature. We report a first documented case of middle ear carcinoid tumor with new bone formation demonstrated on CT imaging and performed a review literature regarding the tumor. A differential diagnosis of neuroendocrine adenoma of the middle ear should be considered when there is prominent bone formation with a soft tissue mass in the middle ear on CT imaging.
1
Introduction
Neuroendocrine adenoma of the middle ear has been described in literature as middle ear adenoma with neuroendocrine differentiation or carcinoid tumor. While there have been several case reports describing imaging features of carcinoid tumors of the ear and middle ear adenomas, in our literature review, we have not found a case where bone formation is described as a prominent radiological feature. We report a first documented case of middle ear carcinoid tumor with new bone formation demonstrated on CT imaging.
2
Case review
A 39 year old Chinese female presented to us with gradual left ear hearing loss over 8 months duration. There was no prior history of trauma or exposure to unusually loud noise. The patient has a history of bilateral ear discharge but did not have any tinnitus, otalgia or giddiness. Clinical examination of the cranial nerves was normal. Otoscopic examination revealed an opaque left tympanic membrane which was retracted. There was erythema noted in the pars flaccida and a slight bulge was seen laterally. Nasal endoscopic findings were normal. Audiogram showed moderate to profound mixed hearing loss in the left ear and profound high frequency sensory neural hearing loss in the right ear.
An unenhanced CT scan of the temporal bones was performed in coronal and axial views for further evaluation. CT scan shows a soft tissue lesion within the left middle ear cavity with an associated irregular bony structure close to the tip of the handle of the malleus and separate from the promontory ( Figs. 1 and 2 ). The left stapes and incus are normal in configuration with an intact incudo-stapedial junction. No bony erosion of the ossicular chain is seen. There is mild sclerosis of the left temporal bone with a retracted tympanic membrane. Given the features of chronic otomastoiditis of the left temporal bone, the soft tissue lesion within the middle ear was thought clinically to be granulation tissue. The irregular bony structure was initially thought to be related to post inflammatory ossicular fixation of the fibro-osseous type.
The patient subsequently underwent a left transcanal excision of middle ear tumor. Intra-operative findings revealed a polypoidal left middle ear mass with a bony mass formed between the malleus and incus inferiorly. The bony structure was free from the surrounding walls of the middle ear and the ossicles ( Fig. 3 ). The ossicular chain is intact and in continuity. The promontory was free of tumor. The middle ear tumor and bony mass were removed completely without disruption to the ossicular chain.
Pathological examination indicated that the tumor has an infiltrative growth pattern. A piece of dense cortical ossicle-like bone was present which was surrounded and focally infiltrated by tumor cells. Tumor tissue was positive for NSE, synaptophysin, AE1/3 and CK7 and negative for chromogranin, CD 56, S100, p63 and CD 117. The final diagnosis was carcinoid tumor (middle ear adenoma with neuroendocrine differentiation) based on the morphological and immunohistochemical findings.
2
Case review
A 39 year old Chinese female presented to us with gradual left ear hearing loss over 8 months duration. There was no prior history of trauma or exposure to unusually loud noise. The patient has a history of bilateral ear discharge but did not have any tinnitus, otalgia or giddiness. Clinical examination of the cranial nerves was normal. Otoscopic examination revealed an opaque left tympanic membrane which was retracted. There was erythema noted in the pars flaccida and a slight bulge was seen laterally. Nasal endoscopic findings were normal. Audiogram showed moderate to profound mixed hearing loss in the left ear and profound high frequency sensory neural hearing loss in the right ear.
An unenhanced CT scan of the temporal bones was performed in coronal and axial views for further evaluation. CT scan shows a soft tissue lesion within the left middle ear cavity with an associated irregular bony structure close to the tip of the handle of the malleus and separate from the promontory ( Figs. 1 and 2 ). The left stapes and incus are normal in configuration with an intact incudo-stapedial junction. No bony erosion of the ossicular chain is seen. There is mild sclerosis of the left temporal bone with a retracted tympanic membrane. Given the features of chronic otomastoiditis of the left temporal bone, the soft tissue lesion within the middle ear was thought clinically to be granulation tissue. The irregular bony structure was initially thought to be related to post inflammatory ossicular fixation of the fibro-osseous type.
