Incidence, Pathology, and Recurrence of Pituitary Adenomas: Study of 647 Unselected Surgical Cases

The incidence of various types of unselected pituitary adenomas based on correlation of pathologic and clinical data was assessed. We investigated 647 cases of unselected pituitary adenomas, which were surgically removed between 1980 and 1993. All cases were examined by immunohistochemistry and electron microscopy. The mean age of patients was 44.0 years with 40.0 years for women (55.2%) and 49.1 years for men (44.8%). Age distribution indicated a remarkable sex difference: 52.4% of women and 26.8% of men were between 21 and 40 years at the time of surgery. Based on immunohistochemistry and electron microscopy, prolactin (PRL) cell adenomas represented 263% of tumors, growth hormone (GH) cell adenomas 12.5%, adrenocorticotrophic hormone (ACTH) cell adenomas 12.4%, oncocytomas 12,4%, and gonadotroph cell adenomas 9.4%. Seventy-three percent of the prolactinomas occurred in women and 73.8% of the oncocytomas were found in men. The incidence of pediatrics pituitary adenomas was 4.6%. All 647 cases were followed up; the mean follow-up period was 96.6 months. In 40 patients (6.2%), the adenoma recurred. Recurrence was common in functioning ACTH cell adenomas (8 cases: 9.5%) followed by silent adenomas (7 cases: 25.9%). Recurrence was noted after 2-96 months (average 28.7 months) following surgery. The shortest remission period was found in a patient with oncocytoma followed by a patient with prolactinoma.