The Growth Rate in Pituitary Adenomas: Measurement by Proliferation Marker Ki 67

Abstract

Conventional histological criteria such as cellular and nuclear polymorphism and rarely observed mitotic figures do not sufficiently explain the biological behavior of pituitary adenomas. Although pituitary adenomas are generally described as benign tumors, they show locally invasive growth which can be demonstrated surgically, radiologically, and histologically (Jefferson 1972; Martins et al. 1965; Landolt 1980; Selman et al. 1986; Scheithauer et al. 1986). Invasive growth has been related to distinct ultrastructural and secretory patterns (Kovacs 1984), to immunohistological findings (Scheithauer et al. 1986), and to tumor size (Selmann et al. 1986). Invasive growth influences the surgical outcome (Balagara et al. 1981; Wilson 1984) as well as the postoperative management of these patients in terms whether radiation therapy should be given or not (Ross and Wilson 1988).