Endocrine Abstracts

It has been generally believed that clinically functioning pituitary adenomas are highly specialized neoplastic lesions, which produce a unique hormone. Increasing body of evidence argue against this concept, since about half of prolactinomas (PRM) and approximately 60% of TSH-secreting adenomas are multihormonal and 30–40% of GH-secreting adenomas co-secrete PRL. Most of classically considered null cell adenomas have been proved to be immunohistochemical positive for gonadotropins and with ultrastructurally morphologic evidence of plurihormonality.

Aim: To evaluate the immunohistochemical hormonal profile of PRM and to establish a potential correlation between multihormonality and their biologic behaviour.

Subjects and methods: After obtaining local Ethical Committee approval, we performed a retrospective study on 19 PRM operated between 1994–2005. Measurements of serum PRL level and tumor size were carried pre- and postoperatively, with serial determinations during dopamine agonist therapy. The surgical specimens were fixed in PFA and immunohistochemically stained by the avidin-biotin peroxidase complex method. The diagnosis was considered PRM when more than 50% of cells stained positive for PRL and multihormonality was defined when more than 10% of cells stained positive for other hormone than PRL.

Results: 9 out of 19 PRM were multihormonal (47.4%)- 5 women and 4 men, aged 21–56 yrs, mean 31 yrs. There was no significant difference between mono and multihormonal PRM concerning gender, age, tumor size and preoperative PRL level. Postoperative mean serum PRL level was significantly higher than in monohormonal PRM (P<0.05). Resistance to DA therapy was encountered only in 3/9 multihormonal PRM.

Conclusions: Plurihormonality in prolactinomas is not a marker of aggressive biological behaviour or predictor of treatment efficiency.