Skull Base and Nonskull Base Chordomas: Clinicopathologic and Immunohistochemical Study with Special Reference to Nuclear Pleomorphism and Proliferative Ability

BACKGROUND. To the authors' knowledge, little is known regarding the relation between the proliferative ability and clinicopathologic parameters in skull base chordomas (SBCs) and nonskull base chordomas (NSBCs). METHODS. The authors investigated 122 conventional chordomas for their clinicopathologic parameters, proliferative ability (MIB-1 labeling index [LI]) and clinical outcome. RESULTS. Primary NSBCs were found to affect more elderly patients and demonstrated a higher MIB-1 LI compared with primary SBCs. Mitosis was more commonly noted in recurrent NSBCs compared with primary NSBCs. Apoptosis was more frequent in elderly patients than in younger patients with regard to both SBCs and NSBCs. Apoptosis also was found to be correlated with necrosis in SBCs, suggesting a common factor for the two different types of cell death. Mucoid matrix was reported to be more abundant in NSBCs than in SBCs, and appeared to occur more often in elder NSBC patients compared with younger NSBC patients. This indicates that it is produced in the later stages of tumorigenesis. In SBCs, several clinicopathologic parameters were found to be correlated with MIB-1 LI. Among them, increased age, recurrence, and nuclear pleomorphism were the only independent factors found to indicate a higher MIB-1 LI. No such parameters were found in NSBCs. However, in these lesions, prognosis was significantly poorer in those cases with nuclear pleomorphism compared with those without. CONCLUSIONS. The results of the current study suggest that nuclear pleomorphism is a prognostic indicator in NSBCs. The proliferative ability of SBCs appears to be closely associated with patient age, clinical status (recurrence), and nuclear pleomorphism.