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the occurrence of carcinoma in the external auditory canal ( eac ) is rare , with an annual incidence of one per one million people , accounting for less than 0.2% of all head and neck cancers .
verrucous carcinoma is a well - differentiated variant of squamous cell carcinoma , which is a low - grade malignancy and described as slow growing , locally destructive , and invasive , but not metastatic .
verrucous carcinoma of the head and neck area occurs predominantly in the oral cavity and larynx , and less commonly in the esophagus and genital area .
histologically , verrucous carcinoma displays keratosis , parakeratosis , hyperkeratosis , papillomatosis , and acanthosis .
the mass may infiltrate deeply with thickened squamous epithelium pushing borders but not invading the basement membrane .
we present a case of squamous cell carcinoma in the eac occurring at a site where verrucous carcinoma had been previously treated .
a slowly growing papillomatous lesion of the eac was repeatedly confirmed by biopsies over several years , but aggravation by the growing mass eventually caused otalgia .
the patient had surgery , and the mass was histologically diagnosed as verrucous carcinoma . during follow - up after surgery , a slow growing remnant
mass was identified . after reviewing the specimen removed at surgery , squamous cell carcinoma was diagnosed . here
a 54-year - old man visited our clinic after 20 days of experiencing intermittent left hearing disturbance , and 1 week of left aural fullness and otorrhea at november 2007 .
he had a history of hypertension and diabetes mellitus for which he was on medication , and had received stenting for an acute myocardial infarction 2 years previously .
a mass and crust were observed on the inferior portion of the left eac on physical examination ( fig .
when we removed the crust on the inferior portion of the eac , it bled easily .
this left eac mass had been identified at another hospital 1 year previously , and a biopsy performed 6 months later led to a diagnosis of hyperkeratosis . during follow - up with left ear dressings at the other hospital ,
the tumor in the left eac increased in size and a new protruding mass on the inferior portion of the tympanic membrane was discovered . according to the temporal bone computed tomography ( ct ) and physical findings ,
the tumor was considered to be granulation tissue , and the patient was observed for 4 years .
when he visited our clinic again because of persistent otorrhea and keratin debris in the left eac at march 2011 , ct revealed bony destruction of the inferior eac wall ( fig .
another biopsy of the mass was performed , and the lesion was reported as papillomatosis ( fig .
2a ) . during treatment with local 25% podophyllin and intravenous antibiotics , the patient developed left - sided facial palsy .
because of the growth of the mass was identified in temporal bone ct and mr ( fig .
3 ) and aggravation of otalgia , on november 2012 , excision via transotic approach was performed .
postoperative follow - up by ct and magnetic resonance imaging revealed invasion of the clivus and meckel 's cave by carcinoma ( fig .
thirty - one months after the transotic excision of the verrucous carcinoma , a further excision was carried out using a transcochlear approach .
the frozen biopsy analysis performed during the surgery identified infiltration of cancer into the middle cranial fossa .
since ackerman   first reported a case of verrucous carcinoma in the oral cavity in 1948 , its occurrence in the eac was not described until 1981 , by woodson , et al .   according to the involved site , verrucous carcinoma is variously referred to as oral florid papillomatosis , giant condyloma of buschke - lwenstein , and epithelioma cuniculatum .
verrucous carcinoma is a rare tumor of the head and neck , the most common sites being the oral cavity and larynx .
it very rarely involves the ear , and only 15 cases have been reported in the literature . although the etiology of verrucous carcinoma is not well defined , the human papilloma virus ( hpv ) is considered one of the etiological factors .
besides hpv , poor hygiene , presence of lichenoid and leucoplakic lesions , chronic irritation and inflammation , smoking , and immunodeficiency are highly associated with verrucous carcinoma of the head and neck .
clinically , verrucous carcinoma is known to be a slowly progressive tumor with locally infiltrative and destructive characteristics , and rarity of distant metastasis .
radiation therapy is considered to be one method of treating verrucous carcinoma , but compared with conventional surgery it is a relatively lower local control rate , and therefore surgery is preferred .
verrucous carcinoma in the oral cavity at an advanced stage can present with lymph node metastasis , for which selective neck dissection should be considered . with a high recurrence rate after surgery , postoperative radiation therapy is recommended for extensive verrucous carcinoma .
histologically , verrucous carcinoma presents as hyperkeratosis , papillomatosis , and acanthosis in the epidermis layer , pushing the margin with broad rete pegs into the dermis .
chronic inflammatory cells are infiltrated around the tumor , and , unlike squamous cell carcinoma , the basement membrane between the epidermis and the dermis appears to be intact .
the common wart is histologically similar to verrucous carcinoma , but it is distinguished by koilocytes , keratohyaline granules , and inward bending of rete ridges into the malpighian layer .
sometimes , a more aggressive squamous cell carcinoma may arise in the verrucous carcinoma lesion .
therefore , for differential diagnosis of verrucous carcinoma , full - thickness biopsies of the lesion are needed for histologic confirmation . in this case , for 4 years each biopsy of the tumor was identified as hyperkeratosis and after that the tumor was confirmed as papillomatosis .
one year later , the tumor was confirmed as verrucous carcinoma and , after a further 3 years , squamous cell carcinoma was identified .
the reason for the occurrence of squamous cell carcinoma in this patient is unknown ; however , we can reasonably speculate about the pathology .
first , it might be possible that squamous cell carcinoma existed concurrently with verrucous carcinoma .
the resected tumor was confirmed as verrucous carcinoma , but squamous cell carcinoma could have remained .
verrucous carcinoma shows a relatively low rate of metastasis to other organs , and surgical treatment after early diagnosis is the most effective treatment modality .
if misdiagnosed as a benign lesion clinically and histologically , because of a superficial biopsy , inappropriate treatment will lead to a high recurrence rate .
therefore , any suspicion of verrucous carcinoma should be biopsied with full - thickness of the skin to enable extensive examination of the lesion , and treatment should be excision with a wide safety margin .
carcinoma in the external auditory canal ( eac ) is a rare malignancy with an annual incidence of one per one million people , accounting for less than 0.2% of all head and neck cancers . 
 the most common histopathological type of eac cancer is squamous cell carcinoma . 
 verrucous carcinoma is a well - differentiated , low - grade variant of squamous cell carcinoma . 
 it is a locally destructive , invasive , and slow growing tumor that rarely metastasizes . 
 verrucous carcinoma occurs predominantly in the oral cavity and larynx , and its occurrence in the eac is extremely rare . in this report 
 , we present a histologically confirmed case of verrucous carcinoma in the eac and temporal bone , which for several years had been classified as epithelial hyperplasia . 
 two - and - a - half years after diagnosis of verrucous carcinoma , a recurrent mass was found and the lesion was then confirmed to be squamous cell carcinoma .