Ki-67 labelling index and invasiveness among anterior pituitary adenomas: analysis of 103 cases using the MIB-1 monoclonal antibody

• Published in: Journal of clinical pathology 1999-02, Vol.52 (2), p.107-111
• Main Authors: Mastronardi, L, Guiducci, A, Spera, C, Puzzilli, F, Liberati, F, Maira, G
• Format: Article
• Language: English
• Subjects: Adenoma - pathology; Adolescent; Adult; Aged; Antibodies, Monoclonal; Biological and medical sciences; Cavernous Sinus - pathology; Cell Division; Endocrinopathies; Female; Humans; Hypothalamus. Hypophysis. Epiphysis (diseases); Ki-67 Antigen - analysis; Male; Medical sciences; Middle Aged; Neoplasm Invasiveness; Non tumoral diseases. Target tissue resistance. Benign neoplasms; Pituitary Gland, Anterior; Pituitary Neoplasms - pathology
• ISSN: 0021-9746; 1472-4146
• DOI: 10.1136/jcp.52.2.107

AIMS: To investigate the relation between proliferative activity of anterior pituitary adenomas, quantified by the Ki-67 labelling index, and their invasive behaviour. METHODS: Expression of Ki-67 was evaluated in 103 anterior pituitary adenomas consecutively operated on in a 36 month period and correlated with surgical evidence of invasiveness. RESULTS: Non-invasive (n = 65) and invasive (n = 38) adenomas were identified from surgically verified infiltration of sellar floor dura and bone. The wall of the cavernous sinus was infiltrated in 16 cases. Forty one adenomas were non-functioning and 62 functioning (24 prolactin, 21 growth hormone, 10 ACTH, seven mixed). The overall mean (SD) Ki-67 labelling index was 2.64 (3.69) per cent (median 1.5). The mean index was 3.08 (4.59) per cent in functioning and 1.97 (1.78) per cent in non-functioning tumours; 5.47 (9.52) per cent in ACTH adenomas and 2.33 (2.42) per cent in others (p = 0.01); 3.71 (5.17) per cent in invasive and 2.01 (2.45) per cent in non-invasive adenomas (p = 0.027); and 5.58 (7.24) per cent in cavernous sinus infiltrating v 2.10 (2.39) per cent in cavernous sinus non-infiltrating adenomas (p = 0.0005). To identify a value of labelling index beyond which adenomas should be considered invasive and another beyond which cavernous sinus infiltration should be suspected, normality Q-Q plots were obtained: a threshold labelling index of 3.5% for invasive adenomas and of 5% for cavernous sinus infiltrating adenomas was defined, with statistically significant differences (p = 0.02 and p = 0.004, respectively). CONCLUSIONS: The Ki-67 labelling index can be considered a useful marker in determining the invasive behaviour of anterior pituitary adenomas.