Tumour angiogenesis and Ki-67 expression in phaeochromocytoma

Objective To determine the expression of CD34 (to evaluate vascularity) and Ki-67 (as a proliferative index) in a variety of phaeochromocytomas and th us assess the utility of these markers as possible predictors of malignancy . Patients and methods Deparaffinized tissue sections from 21 patients with b enign and four with malignant phaeochromocytoma were assessed immunohistoch emically to evaluate microvascular counts (using CD34 antigen) and the prol iferative index (Ki-67 antigen, monoclonal antibody MIB-1). Results There was no statistical association between high microvascular cou nts and malignancy, but there was between the MIB-1 score and malignancy (P < 0.001). Conclusions A high MIB-1 score in phaeochromocytoma suggests malignant beha viour in the component cells. The MIB-1 score may be a useful indicator for diagnosing malignant phaeochromocytoma.