title: Diagnosis and surgical treatment of a malignant trichoepithelioma of the ear canal in a pet rabbit (Oryctolagus cuniculus).
abstract: METHODS
  A 10-year-old spayed female Holland Lop-mix pet rabbit (Oryctolagus cuniculus) was evaluated because of purulent-hemorrhagic discharge from the right ear canal and a suspected mass within that ear canal.
  
  
  RESULTS
  Results of contrast-enhanced CT, video otoscopy, and histologic examination of endoscopic tissue biopsy samples indicated severe otitis media and externa and a benign trichoepithelioma of the right ear canal.
  
  
  RESULTS
  Total ear canal ablation and lateral bulla osteotomy were performed. Histologic examination of a surgical biopsy sample of the mass indicated malignant trichoepithelioma. Tumor recurrence was detected 22 weeks after surgery. The rabbit was euthanized 33 weeks after surgery because of the large size of the recurrent tumor and declining quality of life. Necropsy findings indicated a malignant trichoepithelioma with local and lymphatic invasion into the right mandibular lymph node.
  
  
  CONCLUSIONS
  This was the first report of the clinical diagnosis, surgical treatment, and outcome for a domestic rabbit with a diagnosis of a malignant trichoepithelioma of the ear canal and associated otitis media and externa. Neoplasia should be included as a differential diagnosis for pet rabbits with otitis externa and media. Although such tumors are typically benign, trichoepitheliomas in rabbits can be malignant. Computed tomography and histologic examination of tissue samples were useful diagnostic techniques, but histologic examination of an endoscopic biopsy sample did not allow identification of malignant characteristics of the trichoepithelioma.
authors.affiliation: Departments of Surgical Sciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI 53706.
authors.forename: Casey
authors.initials: C
authors.lastname: Budgeon
authors.forename: Christoph
authors.initials: C
authors.lastname: Mans
authors.forename: Tamara
authors.initials: T
authors.lastname: Chamberlin
authors.forename: John
authors.initials: J
authors.lastname: Stein
authors.forename: Randi
authors.initials: R
authors.lastname: Drees
authors.forename: Cecilia
authors.initials: C
authors.lastname: Robat
authors.forename: Marie
authors.initials: M
authors.lastname: Pinkerton
authors.forename: Denise M
authors.initials: DM
authors.lastname: Imai
authors.forename: Jonathan
authors.initials: J
authors.lastname: McAnulty
mesh_terms: D000818:Animals; D002277:Carcinoma / Q000601:surgery / Q000662:veterinary*; D004424:Ear Canal / Q000473:pathology* / Q000601:surgery*; D004428:Ear Neoplasms / Q000601:surgery / Q000662:veterinary*; D005260:Female; D009362:Neoplasm Metastasis; D009364:Neoplasm Recurrence, Local / Q000662:veterinary; D057805:Pets; D011817:Rabbits