Immunohistochemical staining of cathepsins B, L and stefin A in human hypophysis and pituitary adenomas.

BACKGROUND New biological markers are needed for diagnosis of atypical pituitary adenoma. The study aimed to evaluate cathepsins B and L and inhibitor stefin A in relation to their aggressive progression. PATIENTS AND METHODS We evaluated 19 adenomas and 10 normal hypophyses. Adenomas were divided according to their histological features and according to their functional activity, e.g. hormones secretion. Immunohistochemical labelling was scored for cathepsins and stefin A. RESULTS High immunohistochemical scores for cathepsins B and L were more frequent in atypical pituitary adenoma. Higher cathepsin B scores were also observed in functional compared with non-functional tumours, independently of their histology. Stefin A labelling was observed in 90% of normal hypophyses, but only in 10% of adenomas: CONCLUSION The levels of cathepsins B and L antigens are significantly higher in histologically atypical adenomas. Cathepsin B is also a marker of functional activity of the neoplastic glands. Therefore, we propose that this enzyme is evaluated as a diagnostic marker for tumour progression in non-functional adenomas, to distinguish atypical from benign tumours.