Endocrine Abstracts

Background: The first-line treatment in acromegaly is transsphenoidal adenomectomy of GH-secreting pituitary tumor. Pathologic evaluation of postoperative tissue is an essential part of patient’s assessment.

Aim: The aim of this study was to analyse pathologic characteristics of pituitary tumors in patients with acromegaly.

Patients and methods: One hundred twenty patients with acromegaly after at least one pituitary surgery treated in Endocrinology Department in Bielanski Hospital in Warsaw, Poland were included in this retrospective study. The data on demographics, hormonal, imaging and pathologic results were extracted from the Polish Acromegaly Registry. The study focused on comparison between sparsely (SG) and densely granulated (DG) tumors, GH(+), GH(+) PRL(+) and plurihormonal tumors, α-subunit (α-SU)-positive and α-SU-negative tumors and tumors of various Ki-67 index values in terms of above-mentioned characteristics.

Results: SG tumors occurred in 59 patients (55.66%) and DG tumors were diagnosed in 47 patients (44.34%). SG tumors compared to DG tumors were more frequent in women than in men (73.47% vs. 26.53%, P=0.001) and in younger patients [median=39 years (IQR:32–49) vs. 46 years (IQR:38–58), P=0.011]. SG tumors were larger than DG tumors [23 (IQR:20–34) mm vs. 13 (IQR:9–20) mm, P<0.001].

Sixty-three tumors stained positive only for GH in immunohistochemistry (IHC) evaluation (53.39%), 46 tumors stained positive for GH and PRL (38.98%) and 9 tumors stained positive for at least three anterior pituitary hormones including GH (7.63%). Patients with GH(+)-PRL(+)-tumors presented with higher PRL concentration and more frequent gonadotropin insufficiency (P=0.004 and P=0.022, respectively).

Forty-nine tumors stained positive for α-SU (41.88%) and 62 tumors stained negative (52.99%). Tumors with α-SU(+) were smaller and were more often DG tumors compared to tumors with α-SU(−) [16.0 mm (IQR: 10–21) vs. 20.0 mm (IQR: 14–31), P=0.013 and 75.51% vs. 35.71%, P<0.001, respectively]. Tumors with α-SU(+) expanded extrasellarly less often than α-SU(−)-tumors (40.0% vs. 61.02%, P=0.039).

Proliferation index Ki-67 < 1% was found in 89 patients (76.72%) and Ki-67 ≧ 3% in 11 patients (9.48%). Patients with higher Ki-67 index were younger at diagnosis of acromegaly (P<0.001) and more often diagnosed with genetic syndromes (P=0.02), they had higher GH concentration (P=0.007), larger tumors (P=0.006) and cavernous sinuses invasion more frequently (P=0.022).

Conclusions: Pathologic assessment is an important part of acromegaly patients’ evaluation. Pathologic characteristics are associated with patient’s age, sex, hormonal results, tumor’s size and degree of extrasellar expansion.