DNA topoisomerase II-alpha in pulmonary carcinoid tumors.

Fifty-four pulmonary carcinoid tumors of surgically treated patients were diagnosed according to modified Arrigoni histological criteria (WHO 1999). Forty-seven typical (TC) and seven atypical carcinoids (AC) formed the basic groups. Four subgroups were selected from the TCs and consisted of cases with higher tumor size (T2) or those associated with nodal involvement (N1), tumor satellites, and tumorlets. Subgroup tumors were regarded as affections with possible increased proliferation potential. The proliferate activity was examined immunohistochemically by topoisomerase II-alpha (clone SWT3D1) on paraffin material and calculated by the number of positive nuclei per 10 HPF. The topoisomerase expression was found to be statistically different in both principal groups made up of typical and atypical carcinoids with a mean value of 49 and 135 positive nuclei per 10 high power field in TC and AC, respectively. The remaining subgroups of the TCs associated with examined characteristics (larger tumor diameter, metastases, satellites, tumorlets) were not found to be statistically different. The topoisomerase II-alpha is a marker giving valuable information about the diagnosis of pulmonary typical and atypical carcinoids.