Typical and atypical bronchopulmonary carcinoid tumors: a clinicopathologic and KI-67-labeling study

Expression of a proliferating antigen by KI-67 immunohistochemistry was analyzed with a SAMBA 2005 computer-assisted image processor (Traitement de l'Information for des Techniques Nouvelles, Grenoble, France) in 47 surgically resected bronchopulmonary carcinoids embedded in paraffin. The clinicopathologic characteristics and KI-67 labeling, expressed in percentage of stained nuclear surface relative to the total nuclear surface, of 31 typical carcinoids and 16 atypical carcinoids were compared and assessed with respect to patient survival. The proliferation status was significantly higher in histologically atypical than in typical carcinoids. Moreover, using a 4% cutoff, we observed a significant difference for the 4-year overall survival rate. Semiquantitative analysis of the proliferation index by KI-67 immunostaining seemed to be an effective means of identifying high risk subsets among patients with histologically atypical carcinoids and for whom adjuvant chemotherapy could be proposed.