title: CT and MRI findings of radiation-induced external auditory canal carcinoma in patients with nasopharyngeal carcinoma after radiotherapy.
abstract: OBJECTIVE
  To summarize the radiological and clinical features of radiation-induced external auditory canal carcinomas (RIEACCs) in patients with nasopharyngeal carcinomas (NPCs) after radiation therapy.
  
  
  METHODS
  CT, MRI and clinical features in 16 patients with histologically proven RIEACCs were retrospectively reviewed. There were 2 females and 14 males, with a median age of 52.5 years at the time of diagnosis of RIEACC. Imaging parameters including lesion extent, size, margin, shape, bone destruction, adjacent structure invasion, density/signal intensity, and pattern and degree of enhancement were assessed. Clinical features including clinical staging, histological type, treatment and radiation dose (RD) of primary NPC as well as the histological type, staging of radiation-induced tumour and the latent period between NPC and RIT were recorded.
  
  
  RESULTS
  All patients had a single RIEACC. The lesions had a size of 3.5 ± 1.4 cm and were localized (n = 7) or extensive (n = 9). Most of the lesions were partially or ill defined with an irregular shape and had an intermediate density/signal pattern and moderate homogeneous enhancement. The latent period of RIEACCs ranged from 10 to 20 years in nine patients with a RD of 68-70 Gy; from 2 to 10 years in five patients with a RD of 68-74 Gy; and more than 20 years in two patients with a RD of 70 or 72 Gy.
  
  
  CONCLUSIONS
  An external auditory canal (EAC) mass with homogeneous, intermediate CT density or signal intensity in patients with NPC after radiotherapy is highly suggestive of RIEACC, which should be included in the routine surveillance for patients with NPC after radiotherapy.
  
  
  CONCLUSIONS
  RIEACCs could occur as short as 2 years after radiotherapy in patients with NPC and have distinct features from otitis media and sarcomas. This EAC malignancy should be included in routine surveillance for patients with NPC after radiotherapy.
authors.affiliation: 1 Department of Radiology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China.
authors.forename: X
authors.initials: X
authors.lastname: Zhang
authors.forename: S
authors.initials: S
authors.lastname: Bai
authors.forename: H
authors.initials: H
authors.lastname: Li
authors.forename: H
authors.initials: H
authors.lastname: Hu
authors.forename: X
authors.initials: X
authors.lastname: Duan
authors.forename: M
authors.initials: M
authors.lastname: Chen
authors.forename: D
authors.initials: D
authors.lastname: Wang
authors.forename: Y
authors.initials: Y
authors.lastname: Chen
authors.forename: F
authors.initials: F
authors.lastname: Zhang
authors.forename: J
authors.initials: J
authors.lastname: Shen
mesh_terms: D000328:Adult; D004424:Ear Canal / Q000528:radiation effects*; D004428:Ear Neoplasms / Q000175:diagnosis* / Q000209:etiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009303:Nasopharyngeal Neoplasms / Q000532:radiotherapy*; D009381:Neoplasms, Radiation-Induced / Q000175:diagnosis*; D011879:Radiotherapy Dosage; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed
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