RESUMO
Background: Growth hormone (GH) producing adenomas, frequently express several hormones. This condition could confer them a higher proliferative capacity. Ki-67 is a nuclear protein antigen that is a marker for proliferative activity. Aim: To measure the immunohistochemical hormone expression in pituitary adenomas, excised from patients with acromegaly. To determine if the pluríhormonal condition of these adenomas is associated with a higher proliferative capacity, assessed through the expression of Ki-67. Material and methods: Forty one paraffin embedded surgical samples of pituitary adenomas from patients with acromegalia were studied. Immunohistochemistry for GH, prolactin (PRL), follicle stimulating hormone (FSH), luteinizing hormone (LH), thyroid stimulating hormone (TSH), adrenocorticotropin (ACTH) and for the expression of Ki-67 was carried out. Results: All samples were positive for GH. Twenty seven had positive staining for PRL, 12 had positive staining for glycoproteic hormones and 11 for PRL and one or more glycoproteic hormones. Mean staining for Ki-67 was Z.6±3.3 percent. There were no differences in the expression of this marker between mono or pluríhormonal tumors. The expression was neither associated with extrasellar extensión. Conclusions: Half of GH producing pituitary adenomas are pluríhormonal. There are no differences in the expression of Ki-67 between mono and plurihormonal adenomas.