title: Clinical Characteristics of Epidermoid Cysts of the External Auditory Canal.
abstract: OBJECTIVE
  The epidermoid cyst is a common benign disease of the skin caused by inflammation of hair cortex follicles and proliferation of epidermal cells within the dermis or superficial subcutaneous tissue. The purpose of this study was to investigate the characteristics of epidermoid cysts of the external auditory canal (EAC) by analyzing the clinical and radiologic features.
  
  
  METHODS
  The clinical records were retrospectively reviewed for patients diagnosed with epidermoid cyst of the EAC from March 2004 to December 2013. The epidermoid cysts were diagnosed clinically by endoscopy and microscopy examinations and by temporal bone CT images, and were confirmed by histopathologic examination. Characteristics of epidermoid cysts in bony EAC and cartilaginous EAC were compared.
  
  
  RESULTS
  Eight patients had an epidermoid cyst in the bony EAC and nine patients had one in the cartilaginous EAC. Swelling and otalgia were common symptoms, but 47% of cysts were found incidentally. The mean age of patients was 49.6 years (age range, 26-67 years) in the bony EAC cases and 26.1 years (age range, 6-57 years) in the cartilaginous EAC cases. The mean size of the epidermoid cyst was 3.50 mm (size range, 2-7 mm) in the bony EAC cases and 9.55 mm (size range, 2-20 mm) in the cartilaginous EAC cases.
  
  
  CONCLUSIONS
  Comparison of epidermoid cysts of the bony EAC and the cartilaginous EAC revealed that epidermoid cysts of the bony EAC is usually found incidentally, arose in older patients and had smaller size.
authors.affiliation: Department of Otorhinolaryngology-Head & Neck Surgery, College of Medicine, Hallym University, Seoul, Korea.
authors.forename: Go-Woon
authors.initials: GW
authors.lastname: Kim
authors.affiliation: Department of Otorhinolaryngology-Head & Neck Surgery, College of Medicine, Hallym University, Seoul, Korea.
authors.forename: Jang-Hee
authors.initials: JH
authors.lastname: Park
authors.affiliation: Department of Otorhinolaryngology-Head & Neck Surgery, College of Medicine, Hallym University, Seoul, Korea.
authors.forename: Oh-Joon
authors.initials: OJ
authors.lastname: Kwon
authors.affiliation: Department of Otorhinolaryngology-Head & Neck Surgery, College of Medicine, Hallym University, Seoul, Korea.
authors.forename: Dong Hyun
authors.initials: DH
authors.lastname: Kim
authors.affiliation: Department of Otorhinolaryngology-Head & Neck Surgery, College of Medicine, Hallym University, Seoul, Korea.
authors.forename: Chang Woo
authors.initials: CW
authors.lastname: Kim
keywords: Epidermoid cyst; External auditory canal; Incidental findings