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 thus assess the utility of these markers as possible predictors of malignancy. Patients and methods Deparaffinized tissue sections from 21 patients with benign and four with malignant phaeochromocytoma were assessed immunohistochemically to evaluate microvascular counts (using CD34 antigen) and the proliferative index (Ki-67 antigen, monoclonal antibody MIB-1). Results There was no statistical association between high microvascular counts 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 behaviour in the component cells. The MIB-1 score may be a useful indicator for diagnosing malignant phaeochromocytoma.