title: Immunohistochemical investigations on external auditory canal cholesteatomas.
abstract: OBJECTIVE
  The aim of the study was to analyze the biological behavior of external auditory canal cholesteatoma (EACC). The expression and distribution of relevant markers such as transforming growth factor-alpha (TGF-alpha), epidermal growth factor-receptor (EGFR), and the proliferation marker MIB 1 were studied in comparison with normal auditory meatal skin.
  
  
  BACKGROUND
  EACC are uncommon and knowledge concerning etiology and pathogenesis is limited. Whether this is a unique entity remains controversially discussed.
  
  
  METHODS
  Immunohistochemical methods were used to study the expression and distribution TGF-alpha, EGFR, and the proliferation marker MIB 1 on 15 tissues samples. Only the spontaneous form of EACC was included in this study.
  
  
  RESULTS
  Positive immunoreactivity for the proliferation marker MIB 1 could be demonstrated in keratinocytes in the basal and suprabasal layers of the epithelium. The number of MIB 1-positive proliferating cells in cholesteatoma was significantly higher than in normal external auditory skin. Cholesteatoma epithelium also showed an enhanced expression of TGF-alpha and EGFR. Inflammatory infiltrate was observed in the perimatrix to various degrees.
  
  
  CONCLUSIONS
  These results suggest that similar to the middle ear cholesteatoma, a chronic inflammatory process underlies the EACC, and the inflammatory stimuli may alter keratinocyte proliferation.
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002455:Cell Division / Q000502:physiology; D018424:Cholesteatoma, Middle Ear / Q000473:pathology*; D004424:Ear Canal / Q000473:pathology; D004848:Epithelium / Q000473:pathology; D066246:ErbB Receptors / Q000032:analysis*; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D015603:Keratinocytes / Q000473:pathology; D019394:Ki-67 Antigen / Q000032:analysis*; D008297:Male; D008875:Middle Aged; D008940:Mitotic Index; D010032:Otitis Externa / Q000473:pathology; D012016:Reference Values; D016211:Transforming Growth Factor alpha / Q000032:analysis*
chemical_list: D019394:Ki-67 Antigen; D016211:Transforming Growth Factor alpha; D066246:ErbB Receptors