Case Report Primary Pleomorphic Adenoma of the External Auditory Canal: A Case Report and Review of the Literature Chizu Saito, 1 Takeharu Kanazawa, 1,2 Takehiko Yamaguchi, 3 Ken-ichi Nakamura, 1 and Keiichi Ichimura 1 1 Department of Otolaryngology/Head and Neck Surgery, School of Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke 329-0498, Japan 2 Department of Otolaryngology, Shin-Oyama City Hospital, 1-1-5 Wakagi-cho, Oyama 323-0028, Japan 3 Department of Pathology, School of Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke 329-0498, Japan Correspondence should be addressed to Takeharu Kanazawa; kanatake@omiya.jichi.ac.jp Received 29 January 2014; Accepted 9 March 2014; Published 7 April 2014 Academic Editor: Renzo Mora Copyright © 2014 Chizu Saito et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Background. Pleomorphic adenoma (PA) is a benign tumour that mainly arises from salivary glands, and PA of the external auditory canal (EAC) is very rare. Te objective of this study was to clarify the clinical presentation and treatment of PA of the EAC. Method. Te authors present a case of PA arising from the EAC together with a literature review. Results. A 40-year-old man complained of hearing loss and foreign-body sensation of the right ear. Clinical and radiological examinations revealed a well- defned tumour limited to the EAC, with no connection to the parotid gland. Preoperative fne-needle aspiration cytology fndings were characteristic of PA. Te tumour was removed en bloc with the overlying skin. Conclusion. PA of the EAC is very rare, and methods to rule out malignancy before treatment are lacking. Tus, long-term follow-up is necessary, because malignant tumours are common in the EAC and PA has malignant potential. 1. Introduction Pleomorphic adenoma (PA) is a benign tumour that mainly arises from the salivary glands [1]. However, PA may also arise from the external auditory canal (EAC), although reports are very rare. Since 1951, when Mark and Rothberg published their frst EAC pleomorphic adenoma report [2], at least 35 similar cases have been reported [3–13]. PA of the EAC is classifed as a type of ceruminal gland tumour. Te ceruminal glands may give rise to both benign and malignant tumours. According to the World Health Organization (WHO) classi- fcation [14], the benign tumours include adenoma, pleomor- phic adenoma, and syringocystadenoma papilliferum, and the malignant tumours include adenocarcinoma, adenoid cystic carcinoma, and mucoepidermoid carcinoma. Cerumi- nal tumours are frequently malignant with a poor prognosis and extend to the middle ear inducing signifcant hearing loss [8]. PA arising from the EAC is the rarest type of ceruminal gland tumour, and there is a scarcity of information regarding diferentiation between PA and malignant tumours. In this case report, we describe a rare fnding of a PA arising from the EAC and review the literature on these tumours. 2. Case Report A 40-year-old man was admitted to our hospital with hearing loss and foreign-body sensation of the right ear that had been present for the previous 5-6 years. Ear discharge and pain were absent, but a tumour covered by normal skin was observed in the right EAC. A pure-tone audiogram revealed conductive hearing loss of 30 dB (Figure 1). A computed tomography (CT) scan showed that the sof tissue mass was confned to the right EAC, with no erosion of adjacent bone. On magnetic resonance imaging (MRI), the tumour was detected as a 2.3 × 2.1 × 1.8 mm mass on the posterosuperior wall of the EAC, with low signal intensity on T1-weighted, high signal intensity on T2-weighted, and homogeneous enhancement on gadolinium-enhanced T1- weighted images (Figure 2). Tere was no connection with Hindawi Publishing Corporation Case Reports in Otolaryngology Volume 2014, Article ID 975151, 4 pages http://dx.doi.org/10.1155/2014/975151