Immunoreactivity for Glycoproteic Hormones and Tumor Size in Pituitary Adenomas

Abstract

At least one fifth of pituitary adenomas exhibit plurihormonality when using immunohistochemistry for anterior pituitary hormones. However, the correlation with clinical features is weak, without an agreement upon pathological predictors of tumor behavior. The aim was to determine the immunoreactivity for anterior pituitary hormones and alpha subunit in 276 consecutive pituitary adenomas patients, aged 22-79 years (44.3 ± 8), 154 F/ 122 M: 83 acromegalics (ACM), 173 nonfunctioning adenomas (NFA) and 20 prolactinomas (PRM) submitted to surgery via transfrontal (81) or transsphenoidal (195) along 10 years (1995-2005). In addition, clinical data, hormonal secretion and tumour size were evaluated before pituitary surgery. Local ethical committee approved the study design. The immunoreactivity performed by the avidin-biotin-complex method was evaluated for beta FSH, LH, TSH, alpha subunit, PRL and GH, using a semiquantitative scale of stained cells: strong (>20%), positive (10-20%), weak (5-10%) and negative ( 10% of stained cells) was between 1-2 cm in 6 ACM, 21 NFA and 2 PRM, while positive bigger tumors (2-4 cm) were in 7 ACM, 24 NFA and 2 PRM. Giant, over 4 cm tumors were positive in 3 ACM, 8 NFA and no PRM. A similar trend of the tumor size distribution was observed in the monohormonal or null cell adenomas. In conclusion, tumor size and gonadotrophin plurihormonality are independent factors in the management of pituitary adenomas.