Pleomorphic Adenoma of External Auditory Canal: Case Report of First Endoscopic Resection and Literature Review

Abstract

Ceruminous pleomorphic adenoma is a very rare, mostly benign tumor originating from the ceruminal glands in the external auditory canal. Histologically, it is a mixed tumor with epithelial and stromal parts of different proportions, and is recognized today by the World Health Organization (WHO) as a ceruminous adenoma. Similar to the pleomorphic adenoma of salivary glands, recurrence or malignant degeneration with cellular atypia and metastasis can occur on rare occasions. Here, we describe an 87-year old female patient with a growing spherical mass in the right external auditory canal. After exclusive endoscopic tumor resection, a ceruminous pleomorphic adenoma was histologically diagnosed. Due to the absence of nuclear pleomorphism, no increased mitotic rate, no perineural invasion and no fusion transcripts of the MYB or MYBL1 gene loci, an adenoid cystic carcinoma could be excluded. The postoperative course was without any evidence of complications. A literature review identified 44 articles with 49 patients that were considered. Hearing loss and ear sensations were the most commonly reported symptoms. Most cases underwent an excision via an endaural or retroauricular approach. Recurrences were described in four patients, three of which had a malignant transformation.

Pleomorphic adenoma of the external auditory canal

“…The term ‘’chondroid syringoma” is used to describe a pleomorphic adenoma arising from skin appendages, but authors have opined that the term “chondroid syringoma” can be used interchangeably with pleomorphic adenoma in the EAC. 25 , 26 …”

“…Sufficient surgical therapy with wide margins is hence advocated, accompanied by regular and long-term follow-up as recurrence may occur after complete local excision. 25 , 30 …”

Pleomorphic adenoma in the external auditory canal: Arising at an atypical location

“…At times, endoscopic surgical resection may be performed. 11 Adequate surgery and long-term follow-up is mandatory because of its potentiality to recur and convert into malignancy. Botha and Khan reported the first malignant relapse of pleomorphic adenoma with satellite nodules 3 years after the first excision.…”