neuroendocrine cells are generally present in the respiratory epithelium as well as in the bronchial and intestinal mucosa . a few of these cells are also associated with epithelial structures found throughout the body , including the head and neck . adenomas with neuroendocrine differentiation are defined as neuroendocrine neoplasms , and they are rarely found in the head and neck . when they occur in this region , patient 1 was a 41-year - old woman who presented with a 3-year history of left aural fullness associated with ipsilateral , the patient developed left - side otalgia and was treated with systemic antibiotics but without any improvement . the patient consulted a colleague who raised the possibility of a tympanic paraganglioma . computed tomography ( ct ) of the temporal bones revealed a material with a soft tissue density that diffusely obliterated the left mastoid cells , but with no signs of ossicular chain erosion ( figure 1 ) . angiography of the temporal bone showed a lobulated solid lesion with defined limits and contrast uptake within the left middle ear and the epitympanic recess . 
 computed tomography of the temporal bones revealed a material with a soft tissue density that diffusely obliterated the left mastoid cells , but with no signs of ossicular chain erosion.a . otoscopy of the right ear was normal , but a retrotympanic , non - pulsatile mass was detected in the left ear ( figure 2 ) . figure 3 demonstrates her puretone audiometry , with a 10db - gap in the left ear . intraoperatively , the tumor had a fibrous aspect and filled the antrum and the entire tympanic cavity , involving the ossicular chain . patient 2 was a 41-year - old man who presented with unilateral conductive hearing loss . ct scan showed a middle ear mass in the promontory mimicking a tympanic paraganglioma ( figure 4 ) . magnetic ressonance imaging ( mri ) of the temporal bones revealed a small mass in the left tympanic cavity with isosignal in t1 and post - contrast enhancement on t2 sequences(figure 5 ) . the patient underwent surgical intervention through a supra - meatal approach that completely removed the mass . the tumor was brownish and elastic , involved the ossicles and extended to the promontory . histology and immunohistochemical reactions were also compatible with middle ear adenoma with neuroendocrine differentiation ( figure 6 ) . 
 computed tomography of the temporal bones revealing a small soft tissue density material in the left tympanic cavity . a. coronal b. axial  
 a : mri of the temporal bones revealing a small mass in the left tympanic cavity with isosignal in t1 ( a ) and post - contrast enhancement on t2 . : well - differentiated papillary / trabecular / solid epithelial neoplasm composed of medium - sized cells . central nuclei presented salt - and - pepper  like chromatin , and granular eosinophilic cytoplasm . b - c : immunohistochemical identification keratins marked by the antibodies ae1  +  ae3 and most of them were reactive for neuroendocrine markers chromogranin and synaptophysin d : ki-67 ag was expressed in very low level ( < 1  % of the cells ) . in 1980 , murphy et al . first reported a middle ear adenoma with neuroendocrine differentiation , also called carcinoid tumor , as various denominations are used for these neoplasias , reflecting the controversy between its presumed histogenesis and differentiation3 . the incidence of this tumor in the middle ear is difficult to establish since it may be confused with adenomatous tumors , ceruminomas , and even with other tumors , such as paragangliomas1 . less frequently , patients may complain of tinnitus , headache , and even facial paralysis5 . in most cases , otoscopy demonstrates an intact tympanic membrane with a retrotympanic mass , as occurred in this case . carcinoid syndrome ( flushing , sweating , and diarrhea ) is not found in these patients because of the small production of vasoactive peptides . imaging studies consistently show a locally infiltrative mass and may show invasion of the ossicles4 . middle ear adenoma with neuroendocrine differentiation can be distinguished from adenomatous tumors ( adenomas , adenocarcinomas , and adenoid cystic carcinomas ) , ceruminomas , and paragangliomas by their light microscopic appearance , argyrophilic granules , and ultrastructural evidence of neurosecretory granules , as well as by immunohistochemical detection of various neuroendocrine markers . these include neuron - specific enolase , chromogranin , synaptophysin , serotonin , glucagon , insulin , gastrin , vasoactive intestinal polypeptide , pancreatic polypeptide , and calcitonin4 . we reported two cases of middle ear adenoma with neuroendocrine differentiation wich presented with unspecific clinical manifestations . in both cases , the radiological features were very similar to tympanic paraganglioma , wich is the most frequent tumoral lesion of the middle ear . the recommended treatment is complete surgical excision of the lesion and the technique used is determined by the size and involvement of adjacent structures1 . the prognosis is good , however , a rigorous postoperative follow - up is indicated for all patients3 . our patients underwent surgical treatment and clinical follow - up in conjunction with the oncology department . one of the patients ( patient 1 ) had imaging studies performed 18 months after surgery , wich confirmed that there were no signs of disease recurrence . middle ear adenoma with neuroendocrine differentiation is a rare entity , but it should be considered as a possible diagnosis in patients with hearing loss , tinnitus , aural fullness , and a retrotympanic mass .
summary 
 introduction :  adenomas with neuroendocrine differentiation are defined as neuroendocrine neoplasms , and they are rarely found in the head and neck . 
 objective :  to describe two cases of a middle ear adenoma with neuroendocrine differentiation , with a literature review . 
 case report :  patient 1 was a 41-year - old woman who presented with a 3-year history of left aural fullness associated with ipsilateral 
 hammer beating 
 tinnitus . 
 patient 2 was a 41-year - old male who presented with unilateral conductive hearing loss . 
 conclusion :  adenoma with neuroendocrine differentiation of the middle ear is a rare entity , but it should be considered in patients with tinnitus , aural fullness , and a retrotympanic mass and remembered as a diferential diagnosis of tympanic paraganglioma .