[Pituitary tumors: hormonal status and immunohistochemical evaluation]

New imaging modalities and hormonal diagnostic improvement have markedly increased the number of newly recognized pituitary tumours. Introduction of immunohistochemical assays in histopathological diagnostics of pitutary adenomas resulted in better understanding of pathology and clinics of these neoplasms. The aim of the study was to correlate the hormonal status and hematoxylin-eosin staining results with immunohistochemical staining of pituitary tumours. The study included 40 patients aged 43.8 +/- 18.3 years, diagnosed with a pituitary tumour in the Department of Endocrinology Collegium Medicum UJ, who subsequently underwent trans-sphenoidal surgery in the Department of Neurosurgery Collegium Medicum UJ. The serum pituitary hormone levels were assessed by means of radioimmuno-assays. The surgically obtained tumour tissue was evaluated both by hematoxylin-eosin and immunohistochemical staining. Using traditional staining 33 patients were diagnosed with chromophobic adenoma, 1 with basophilic adenoma, and remaining 6 with eosinophilic tumour. Immunohistochemical assays were ACTH-positive in 16, TSH-positive in 7, GH-positive in 14 and PRL-positive in 17 cases. In 15 subjects immunohistochemical staining was positive for at least two pituitary hormones. In 34 of 54 patients with positive immunohistochemical staining results, no increase in corresponding pituitary hormone serum levels was observed. In 5 of 9 patients with negative immunohistochemical staining, no increase in serum hormone level was noted, remaining 4 were characterized by hyperprolactinaemia. Tumour cells were ACTH-positive in 5 of 6 patients with elevated serum ACTH levels and GH- or TSH-positive in all cases of increased levels of these hormones. Only 6 of 15 subjects with hyperprolactinaemia revealed positive PRL immunohistochemical staining.

Positive immunohistochemical staining often do not correlate with elevated basal serum pituitary hormone levels, which may be related to either impaired synthesis or excretion of the hormones by tumour cells. Increased serum levels of ACTH, TSH or GH are usually connected with positive immunohistochemical staining results. Hyperprolacinaemia in cases of PRL-negative assays arises from PRL secretion defects caused by the tumour presence itself.