Clinicopathological analysis of 250 cases of pituitary adenoma under the new WHO classification

Abstract

Pituitary adenomas (PAs) are a common subtype of intracranial tumors. The aim of the present study was to analyse the clinical and pathological features of different types of pituitary adenomas (PAs) according to the 2017 World Health Organisation Endocrine Organ Tumor Classification guidelines. The clinical data of 250 patients with PAs were collected and analysed. Differences in the incidence of invasion, recurrence and apoplexy in patients between high- and low-risk PAs were compared, as were differences in the Ki-67 index between invasive and non-invasive PAs and between recurrent PAs and non-recurrent PAs. Of the 250 cases, 45 cases were diagnosed as somatotroph adenomas, 26 cases as lactotroph adenomas, 1 case as thyrotroph adenoma, 61 cases as corticotroph adenomas, 93 cases as gonadotropin adenomas, 15 cases as null cell adenomas and 9 cases as plurihormonal adenomas. There were 5 types of high-risk pituitary adenoma identified: 17 cases of sparsely granulated somatotroph adenoma, 11 cases of lactotroph adenoma in men, 3 cases of plurihormonal PIT-1 positive adenoma and 42 cases of silent corticotroph adenoma. Crooke's cell adenoma was not identified. High-risk PAs had significantly higher rates of invasion, recurrence and apoplexy compared with that in low-risk types (P<0.001). Invasive PAs had a significantly higher Ki-67 index compared with that in non-invasive PAs (3.5±1.8 vs. 2.8±1.3; P<0.01). Recurrent PAs had a significantly higher Ki-67 index compared with that in non-recurrent PAs (3.9±1.9 vs. 2.8±1.3; P<0.001). According to the 2017 classification criteria, patients most frequently had gonadotrophin cell adenomas, followed by corticotroph adenomas and the proportion of null cell adenomas was reduced. Differences were noted in the proliferation, recurrence and apoplexy characteristics of high-risk PAs and low-risk PAs. The invasion and recurrence of PAs were found to be related to the Ki-67 index.

Keywords: clinicopathological; invasion; pituitary adenoma; recurrence.

Figure 1.

Immunohistochemical staining of different types of pituitary adenomas. Each image is representative of a different tumour type. Representative images of (A) follicle-stimulating hormone, (B) luteinizing hormone, (C) thyroid-stimulating hormone, (D) adrenocorticotropic hormone, (E) growth hormone and (F) prolactin.

Figure 2.

Ki-67 staining was performed on the adrenocorticotropic hormone of pituitary adenoma tissues. The Ki-67 percentage score is defined as the percentage of positively stained tumour cells among the total number of malignant cells assessed. The dark brown stain indicates Ki-67 (+).

Figure 3.

Sex distribution of patients with different types of pituitary adenomas. somatotroph adenoma and corticotroph adenoma were observed most often in female patients, while gonadotropin adenomas were mostly in male patients. GH, somatotroph adenoma; PRL, lactotroph adenoma; ACTH, corticotroph adenoma; TSH, thyrotroph adenoma; NULL, null cell adenoma; MULTI, plurihormonal adenoma.

Figure 4.

Prevalence of patients with different types of pituitary adenomas in different age groups. The age groups encompassing patients aged between 21 and 60 years old accounted for 72% of all patients, and the overall peak incidence of different types of pituitary adenoma was between 41 and 60 years old. GH, somatotroph adenoma; PRL, lactotroph adenoma; ACTH, corticotroph adenoma; TSH, thyrotroph adenoma; NULL, null cell adenoma; MULTI, plurihormonal adenoma.