Pituitary adenomas in acromegaly: Comparison of different adenoma types with clinical data

Adenoma tissues from 309 patients with active acromegaly was examined by routine light microscopy and immunohistochemistry, and selectively by electron microscopy. All adenomas were immunoreactive for growth hormone. Eighty-seven adenomas were monohormonal (28%), 58 were bihormonal (immunoreactive for growth hormone and prolactin) (19%), and 157 adenomas were plurihormonal (51%), with positivity for glyco-proteins and/or their α-subunit as well. The mean tumor size was significantly greater in monohormonal adenomas than in other adenoma types. There was no difference in invasiveness among the various adenoma types. Younger patients showed invasive tumor growth more often. Patients with densely granulated GH cell adenomas had a significantly longer duration of symptoms compared to patients with other adenoma types. More than half of the patients with sparsely granulated GH cell adenomas had a duration of less than 5 yr. There was no correlation between duration of symptoms and tumor size. The preoperative mean GH level was significantly higher in patients with sparsely granulated GH cell adenomas than in those with mixed GH/PRL cell adenomas. The preoperative mean PRL level was significantly higher in patients with bihormonal adenomas than in those with plurihormonal adenomas. There was an inverse correlation between age and preoperative GH and PRL levels. No linear correlation was found between preoperative basal GH and PRL levels. Monohormonal adenomas presented more often with suprasellar and/or parasellar extension than other adenoma types. Our data suggest a positive correlation between tumor extension and preoperative GH and PRL levels. Patients with plurihormonal adenomas were significantly older than patients with sparsely granulated GH cell adenomas and mixed GH/PRL cell adenomas. No significant difference was found between the various adenoma types and the extent of surgical removal, which depends on the degree of invasiveness, tumor size, and extrasellar tumor extension.     

Grading of pituitary adenomas in acromegaly

Summary In a series of 284 adenomas from cases of acromegaly we studied major morphological variables using light microscopical techniques and compared them with immunocytochemical and clinical results.Using our semiquantitative estimations many inter-relationships were observed. We established the density of secretory granules, nuclear pleomorphism and the rate of occurrence of multinuclear tumour cells, as essential features of tumour differentiation. Mitotic activity and invasive growth patterns did not reveal clear dependences.Immunocytochemical analysis of 105 cases showed growth hormone (GH) in nearly all adenomas (98%), prolactin in 68%, and LH in 40%. The other hormones (ACTH, FSH, and TSH) were present at a much lower rate. Monohormonal GH-adenomas were found in only 29% of our cases.Many different combinations of hormone content could be demonstrated without any relationship to morphological or clinical data. From the linear correlations and advanced method of semiquantitative evaluation, the granular density of the tumour cells is the most useful variable for subclassification and grading of pituitary adenomas in acromegaly.This publication contains results from the doctorthesis submitted by M. Riedel (Hamburg 1984)     

Morphological and biochemical relationships in 31 human pituitary adenomas with acromegaly

Summary In 22 pure GH cell adenomas and 9 mixed GH cell-prolactin cell adenomas with acromegaly, we compare the morphological and functional data (secretory activity and granular appearance) with GH levels (radioimmunoassays) in the blood and in the tumor. According to morphological criteria, the secretory activity is marked in 13 cases (Group I), mild in 9 cases (Group II), and weak in 9 others (Group III). The mean values of the plasma GH levels in the 3 groups (80 ng/ml±22; 26.5 ng/ml±2; and 16.89 ng/ml±2 respectively) are significantly different. In 17 densely granulated adenomas and 14 sparsely granulated adenomas, the plasma GH values were very variable. The mean levels of these 2 groups (49.76 ng/ml±22 and 41.8 ng/ml±7.8 respectively) are not significantly different. The GH concentrations in the tumor were also very variable (358 to 78,900 ng/mg). Their highly significant relationship with the granular appearance is an indirect proof of the granular localisation of GH. We distinguish between 4 functional aspects of the GH cell adenoma which define the different levels of synthesis, storage, and excretion. The secretory activity of the GH adenomatous cell varies with the adenomas and differs from that of the normal cell.     

Clinicopathological correlations in pituitary adenomas

Pituitary adenomas are common neuroendocrine neoplasms arising from adenohypophysial cells. Recent progress in our understanding of pituitary tumorigenesis as well as pathways involved in molecular cytodifferentiation of the adenohypophysis has impacted on the classification of pituitary adenomas. The detailed comprehensive classification of pituitary adenomas is now well recognized to reflect specific clinical features and genetic changes that predict targeted treatments, as well as prognostic information for patients with pituitary adenomas. Therefore, the clinical responsibility of pathologists is not only limited to the distinction of pituitary adenomas from other sellar lesions, but also to provide a comprehensive subtype classification using appropriate ancillary tools. In this article, we highlight an approach to clinical diagnosis and pitfalls in the classification of these common neoplasms.     

Histologic and immunohistochemical study of clinically non-functioning pituitary adenomas

Seventy-five clinically non-functioning pituitary adenomas were characterized in terms of their histologic and immunohistochemical features. Fourteen adenomas (18.7%) were positive for hormones other than gonadotropins. These included two somatotroph adenomas, three lactotroph adenomas, four thyrotroph adenomas, four corticotroph adenomas and one unusual plurihormonal adenoma. Fifty-five adenomas (73.3%) were exclusively positive for one or more gonadotropin subunits (β-follicle stimulating hormone, p-luteinizing hormone, and α-subunit of glycoprotein hormones), but negative for other hormones such as growth hormone and β-thyrotropin. Histologically, a papillary arrangement along the capillary was most characteristically observed in the gonadotropin-positive adenomas. Five of six adenomas negative for any pituitary hormones exhibited the typical papillary structure. Thus, approximately 80% of clinically non-functioning adenomas constituted a single tumor group that shared the common histologic features of gonadotroph adenomas. These findings suggest that nearly all tumor types of clinically non-functioning adenomas can be diagnosed solely by light microscopy in combination with immunohistochemistry, and that the vast majority of them may be gonadotroph adenomas.     

Ultrastructure of tubular inclusions in endothelial cells of pituitary tumors associated with acromegaly

Summary Tubular inclusions were present in 13 out of 43 pituitary adenomas of acromegalic patients and in a single chromophobe pituitary adenoma. There were none in 76 other pituitary adenomas with differing endocrinological symptomatology. The arrays were usually located in the perinuclear cistern of capillary endothelial cells. The tubule diameter in osmium fixed material measured 19–26 nm and the light core averaged 6-11 nm. A longitudinal period of about 4.5 nm could be demonstrated with PTA block staining. Fixation with glutaraldehyde and block staining with ethidium bromide as well as permanganate fixation followed by RNAse treatment showed only the core of the tubules consisting of globular subunits. Several histochemical reactions (perchloric acid extraction, methenaminesilver staining, trypsin and DNAse digestion of frozen sections) suggested that the particles consist of a core of DNA coated with protein. No virus multiplication could be detected in cell cultures or in mice inoculated with fresh tumor material. No significant antibody titers against several virus antigens could be demonstrated.Dedicated to Prof. Dr. G. Töndury on the occasion of his 70th birthday.     

垂体腺瘤p53蛋白表达及其意义

目的：研究突变型ｐ５３癌基因在垂体腺瘤中的表达。方法：应用免疫组化ＡＢＣ法检测６４例垂体腺瘤（复发组３１例，非复发组３３例），６例正常垂体、２例垂体瘤中ｐ５３蛋白表达阳性，非复发组中有２例ｐ５３蛋白表达阳性，两组差异有显著性。２例垂体癌ｐ５３蛋白强阳性表达，６例正常垂体无阳性表达。ｐ５３蛋白在不同激素类型垂体腺癌中的阳性表达率差异无显著性。结论：ｐ５３蛋白高表达与少数垂体腺癌在潜在恶性及复发有关，     

Analysis of Cox-2 and thromboxane synthase expression in pituitary adenomas and carcinomas

Recent studies have examined the role of cyclooxygenase-2 (Cox-2) expression in normal pituitaries and pituitary adenomas and have suggested a role for Cox-2 in the regulation of angiogenesis in the pituitary. Thromboxane synthase (TBXAS), which catalyzes the synthesis of thromboxane A2, is one of the downstream enzymes in Cox metabolism and appears to play a role in the regulation of invasiveness and angiogenesis in some neoplasms. To analyze the role of Cox-2 and TBXAS in pituitary tumor progression, we examined normal pituitaries (n = 8), pituitary adenomas (n = 174), and pituitary carcinomas (n = 7) for expression of Cox-2 and TBXAS by immunohistochemistry. Weak Cox-2 and moderate TBXAS expression was present in normal pituitary cells. Most pituitary adenomas showed increased expression of both Cox-2 and TBXAS. Pituitary tumors as a whole, but particularly carcinomas, showed greater Cox-2 expression than did normal pituitaries. Pituitary adenomas and carcinomas also showed greater staining for TBXAS when compared to normal pituitary. Nonfunctional adenomas had significantly higher levels of TBXAS expression compared to functional adenomas (p = 0.017). Adenomas and carcinomas showed similar degrees of staining for TBXAS. In summary, TBXAS appears to be one of the up-regulated downstream enzymes of Cox metabolism in pituitary tumors. Both Cox-2 and TBXAS may play an important role in pituitary tumor development and progression.     

Human pituitary gonadotroph adenomas: Relationship between gonadotropin immunoreactivity and clinicopathologic findings

Clinically nonfunctioning pituitary adenomas are generally seen in middle-aged and older patients, and most of them may be gonadotropin-immunoreactive adenomas, that is, gonadotroph adenomas. Our aim was to clarify the relationships between the gonadotropin immunoreactivity, patient age, sex, and microscopic features in 68 gonadotroph adenomas with special reference to either gonadotropin-immunonegative or intensively immunopositive adenomas. There were 68 patients with gonadotroph adenomas (mean age 54.7 yr) in the study, including 39 men (mean age, 52.8 yr) and 29 women (mean age, 57.4 yr). The adenomas were diagnosed on the basis of immunoreactivity for gonadotropins (β-subunit of follicle-stimulating hormone: β-FSH; β-subunit of luteinizing hormone: β-LH; and the α-subunit of the pituitary glycoprotein hormone: α-SU) by the avidin-biotin peroxidase complex (ABC) method or by the characteristic histological feature of a perivascular or pseudorosette pattern, that is, the cells aligned polarity directed toward the capillaries. Fifty-four adenomas (79%) were positive for one or more gonadotropin subunits and β-FSH was the most common subunit encountered (47/68, 69%). In men β-FSH immunoreactivity was similar among all age groups, whereas in women, it was significantly less frequent in patients who were 50 yr or older, compared to younger patients. Gonadotropin-immunonegative adenomas were seen in 4 men (mean age, 46.8 yr) and 10 women (mean age, 61.5 yr). Among the 22 women aged 50 or over, β-FSH was negative in 12 tumors (55%), whereas in men of the same age group, it was negative in 3 of 26 tumors (12%). The reason for this reduced frequency is not clear, but the postmenopausal state and associated changes in the systemic endocrine state may play a role. Adenomas that were intensively positive for β-FSH showed an unusual morphology other than the characteristic perivascular pattern, regardless of the patients' age and sex; the tumor cells had abundant vacuolated cytoplasms and were arranged in a sheet-like pattern. Electron microscopically, these cells with abundant cytoplasm had well-developed Golgi complexes, suggesting an enhanced activity of gonadotropin synthesis, and these adenomas seem to be endocrinologically, if not clinically, functioning. The results indicate that gonadotroph adenomas may vary from functioning adenomas with intense immunoreactivity and unusual histology to immunonegative and less functioning adenomas, which are more frequent in women 50 yr or older.     

Expression of vascular endothelial growth factor in normal pituitary cells and pituitary adenomas producing adrenocorticotropic hormone

Vascular endothelial growth factor (VEGF) induces endothelial cell proliferation and an increase in capillary permeability. Because the anterior pituitary gland and pituitary adenomas are highly vascular, expression of VEGF was examined immunohistochemically. Some normal pituitary cells stained positively for VEGF, and restaining for ACTH, prolactin, TSH, LH, FSH, and S-100 protein after VEGF staining revealed that almost all cells staining positively for ACTH also stained for VEGF. Only adenomas staining positively for ACTH stained for VEGF. These results suggest that VEGF is produced by normal pituitary cells and adenomas producing ACTH.     

Prolactin-producing pituitary adenoma associated with prolactin cell hyperplasia

A 24-yr-old woman with amenorrhea, galactorrhea, hyperprolactinemia, and sellar mass underwent transsphenoidal surgery. Histologic, immunohistochemical, and electron microscopic investigation revealed a well-differentiated, sparsely granulated prolactin (PRL) cell adenoma of the pituitary showing conclusive PRL immunoreactivity. In the nontumorous adenohypophysis PRL cell hyperplasia was noted. Marked differences were evident between the neoplastic and hyperplastic areas. The tumor consisted of sparsely granulated PRL cells immunoreactive only for PRL. As demonstrated by immunoelectron microscopy, the hyperplastic are a comprised monohormonal sparsely granulated PRL cells as well as bihormonal mammosomatotrophs immunoreactive for both PRL and growth hormone. The MIB-1 index was higher whereas microvessel density was lower in the adenoma as compared with the hyperplastic area. In addition, the nontumorous area showed lymphocytic infiltration whereas inflammatory reaction was not seen in the adenoma. This case represents a rare association of a PRL cell adenoma and PRL cell hyperplasia. The fact that these two lesions were contiguous in the surgically removed material raises the possibility that hyperplasia can precede and transform into adenoma.     

Expression of retinoblastoma protein in human growth hormone-secreting pituitary adenomas

The retinoblastoma gene (RB1) is a tumor-suppressor gene in chromosomal region 13q14.2. Its role in the pathogenesis of pituitary tumors has not been fully clarified. Some studies have shown that losses in this chromosomal region are related to aggressive tumor behavior, although the retinoblastoma protein (pRB) is still expressed. Conversely, lack of expression of pRB was observed in one fourth of GH-secreting pituitary adenomas (GH-tumors). In order to further study the expression of pRB in GH-tumors, we evaluated this protein in 49 tumors from patients with acromegaly (20 noninvasive, 25 invasive, and 4 with no information) and 8 normal pituitaries using immunohistochemistry (IHC). Nuclear staining for pRB ranged from 0 to 90% (median 40%) in the tumors and from 40 to 80% (median 58%) in normal pituitaries. In 10 tumors (20% of total) the adenomatous cells were negative (5 cases) or had very low labeling (5 cases) for pRB. Sixty three percent (31/49) of the tumors showed staining in 10–80% of the cells and in 16% (8/49) of the cases >80% of the adenomatous cells were positive for pRB. The expression of pRB was not different in invasive and noninvasive tumors. In conclusion, pRB is underexpressed in a subgroup of GH-tumors, and this may represent an early event in the pathogenesis of this tumor subtype.     

CD markers in pituitary adenomas

Immunostaining of CD markers in normal pituitary cells has been reported, but a study of these markers in pituitary adenomas has not been done. The expression of CD 3, CD 8, CD 15, CD 20, CD 30, CD 43, CD 45R0, CD 45 R, CD 79 α, and VS-38c was investigated in a collection of 65 pituitary adenomas of various types. CD 3 was present in 75%, CD 8 in 18.5%, CD 15 in 12.3%, CD 20 in 66.1%, CD 30 in 10.8%, CD 43 in 10.8%, CD 45 RO in 72.3%, CD 45 R in 16.9%, CD 79α in 0% and VS-38 c in 44.6%. Densely granulated GH cell adenomas expressed CD 3, CD 20, CD 45 RO, and CD 45 R, but no other markers. Sparsely granulated GH cell adenomas showed CD 3, CD 8, CD 20, CD 43, and CD 45 RO. Mixed GH/prolactin cell adenomas contained CD 3, CD 8, CD 20, CD 30, CD 45RO, CD 45 R, and VS-38c. Mammosomatotroph cell adenomas were positive only for CD 3, CD 8, CD 20, CD 43, and CD 45 RO. Prolactin cell adenomas expressed CD 3, CD 8, and CD 20. ACTH cell adenomas showed CD 3, CD 15, CD 20, CD 30, CD 45 RO, CD 45 R, and VS-38c. TSH cell adenomas contained CD 3, CD 8, CD 15, CD 20, CD 45 RO, and VS-38c. Gonadotroph cell adenomas were positive for CD 3, CD 8, CD 20, CD 45 RO, CD 45 R, and VS-38c. Alpha-subunit-only adenomas expressed CD 3, CD 8, CD 15, CD 20, CD 30, CD 45 RO, and VS-38c. Plurihormonal adenomas contained CD 3, CD 8, CD 20, CD 30, CD 43, CD 45 RO, CD 45 R, and VS-38c. Oncocytic adenomas were positive for all markers except CD 45 RA and CD 79 α. We conclude that the spectra of different adenoma types expressing CD markers varies greatly and that significant correlations do not exist, although noninvasive adenomas appear to express CDs more frequently than invasive adenomas. We have no clear-cut explanations for the various expressions and suggest that it may be a sign of local interactions between the immune system and pituitary adenomas.     

垂体腺瘤免疫微环境及免疫治疗的研究进展

垂体腺瘤(PAs)是第二常见的原发性中枢神经系统肿瘤,多数可通过手术、药物或放射治疗治愈。但是,部分PAs经过传统治疗后仍反复复发并侵袭性生长,甚至发生远端转移,缩短了患者生存期并降低了生活质量。近年来,关于脑肿瘤免疫微环境的研究逐渐兴起,尤其在胶质瘤领域,为免疫治疗提供了潜在有效靶点,为提高患者生存创造了条件。但是,既往研究仅对PAs微环境中免疫细胞、免疫分子及细胞因子进行了初步分析,对动物和人PAs的免疫治疗研究刚刚起步。     

Chromogranin a processing in human pituitary adenomas and carcinomas: analysis with region-specific antibodies

The expression of various chromogranin A (CgA) peptide fragments was examined with region-specific antisera in benign and malignant pituitary tumors. Analysis of the proconvertases responsible for proteolytic processing of CgA, prohormone convertase 1/3 (PC1/3), and PC2 was also performed. Adenomas were studied using tissue microarrays, and a larger tissue section of a subset of the prolactin (PRL) adenomas was used to compare to the tissue microarray analysis. Carcinomas were analyzed using large tissue sections. There were differences in CgA proteolytic products detected between the functional (PRL, adrenocorticotropic hormone [ACTH], and growth hormone tumors and the nonfunctional (gonadotroph and null cell) tumors, with the former group, expressing lower levels of many peptides. These differences were most notable in the PRL adenomas and carcinomas in which the region-specific antisera against vasostatin I and vasostatin II detected these fragments in the lowest percentage of tumors and/or had the weakest immunoreactivity. The CgA peptide fragment detected by CgA 176–195 (chromacin) antiserum was expressed by the highest percentage of most functional and nonfunctional benign and malignant pituitary tumors. ACTH carcinomas (n+3) were more strongly immunoreactive compared to the ACTH adenomas. These results show that there is differential expression of CgA peptide fragments and PC1/3 among different types of pituitary tumors and that ACTH pituitary carcinomas have higher levels of immunoreactive CgA peptide fragments compared to ACTH adenomas. This study also shows the utility of tissue microarrays in the analysis of a large group of tumors with region-specific antisera.     

Plurihormonal pituitary adenomas: immunostaining of all pituitary hormones is mandatory for correct classification

AIMS: We studied the clinicopathological characteristics of plurihormonal pituitary adenomas. METHODS AND RESULTS: The study material included 167 plurihormonal adenomas, which consisted of 31% of the surgically removed pituitary adenomas that we collected during a 12-year period. The mean age of patients with plurihormonal adenoma was 45.7 years (range 13-75 years). There were 86 men and 81 women. All tumours were fully classified by immunohistochemical staining for seven pituitary hormones or subunits. Thirty immunohistochemical subtypes of plurihormonal adenomas were recognized. Hormonal symptoms were present in 70% of patients, while serum hormonal levels were increased in 89% of patients. Most patients had symptoms related to only one of the hormones and only 7% of patients had symptoms related to two hormones. The most common hormonal symptom was acromegaly (50%); symptoms related to hyperprolactinaemia ranked second (20%). Double immunostaining of all the possible combinations of the hormones was performed in 30 selected tumours, and they all showed mixtures of hormones in individual adenoma cells in any hormonal combinations studied. The latter finding supported the view that plurihormonal adenomas are monomorphous adenomas. CONCLUSIONS: Plurihormonal adenomas are common pituitary adenomas. Immunohistochemical staining of all pituitary hormones is mandatory for correct classification.     

Heterogeneous pituitary adenomas

Summary The combined use of several histological procedures (i.e. conventional light microscopy, immunohistochemistry and electron microscopy) among 45 unselected pituitary adenomas demonstrated the existence of 9 tumors (20%) containing several identifiable adenohypophy seal cell types. Thecellular associations were between 2 or 3 identifiable cell types. Mammosomatotrophic tumors were the most frequent but not the only mixed type (somatomammocorticotrophic, somatocorticotrophic tumors were also found). The cellular components varied in size but the cells appeared randomly distributed in the tumors. In all the adenomas there was an unidentified cell component (no reactivity with antisera used) varying from sparse to numerous elements. On adjacent sections the adenomatous cells reacted with a single specific antiserum, but in two cases the immunohistochemistry on contiguous paraffin embedded sections did not confirm this with certainty. These results confirm those of others and a new term is purposed to designate these tumors: heterogeneous pituitary adenomas. According to the nature and the proportions of the cell components the heterogeneous adenomas were subdivided into two groups: a group A which comprised adenomas formed by a major identifiable cellular type associated with one or two other less frequent cell types, and a group B formed by a predominant unidentifiable (no reactivity with immunochemical stainings) cell type associated with one or two other identified cell types. The present morphofunctional classifications of pituitary adenomas should be modified to include homogeneous adenomas with a single cell type and heterogeneous adenomas with several cell types.     

垂体腺瘤中E-cadherin和nm23蛋白表达与肿瘤生物学行为的关系

目的探讨垂体腺瘤中Ecadherin(Ecad)和nm23蛋白表达与肿瘤体积、激素分泌和侵袭性的关系。方法应用免疫组化SP法检测Ecad和nm23基因蛋白在23例侵袭性垂体腺瘤和24例非侵袭性垂体腺瘤组织中的表达。结果Ecad和nm23的表达在侵袭性垂体腺瘤组低于非侵袭性组(P<0.05),Ecad表达在非分泌型垂体腺瘤组低于分泌型组且与肿瘤体积呈负相关(P<0.05),Ecad与nm23表达间呈正相关(P<0.05)。结论Ecad与nm23表达降低可能与垂体腺瘤的侵袭性有关,Ecad表达降低可能影响垂体腺瘤细胞分化和促进细胞增殖,Ecad和nm23可作为评估垂体腺瘤侵袭能力的生物学指标之一。     

Increased expression of HMGA1 correlates with tumour invasiveness and proliferation in human pituitary adenomas

Wang E L, Qian Z R, Rahman M M, Yoshimoto K, Yamada S, Kudo E & Sano T
(2010) Histopathology 56, 501–509 Increased expression of HMGA1 correlates with tumour invasiveness and proliferation in human pituitary adenomas Aims: High‐mobility group A1 (HMGA1) is highly expressed in various benign and malignant tumours. The development of pituitary adenoma in Hmga1 transgenic mice has been reported. However, no studies have investigated HMGA1 expression and its clinical significance in human pituitary adenomas. Methods and results: Immunohistochemical expression of HMGA1 was analysed with respect to various clinicopathological factors in 95 pituitary adenomas. Nuclear expression of HMGA1 was observed in 62% of pituitary adenomas, whereas normal adenohypophysial tissues were negative. Although HMGA1 expression was frequently detected in clinically non‐functioning adenomas – 90% of silent adrenocorticotropic hormone (ACTH), 76.2% of follicle‐stimulating hormone/luteinizing hormone and 100% of null cell adenomas – it was also detected in 48.1% of growth hormone (GH), 60% of mixed GH/prolactin (PRL), 62.5% of PRL, 66.6% of thyroid‐stimulating hormone and 37.5% of ACTH adenomas. HMGA1 expression was significantly higher in invasive adenomas or macroadenomas than in non‐invasive adenomas or microadenomas (invasive versus non‐invasive, P < 0.05; macroadenoma versus microadenoma, P < 0.05). In addition, HMGA1 showed the highest level in grade IV, more aggressive pituitary adenomas, than in grades I, II and III (IV versus I, P = 0.01; IV versus II, P = 0.01; IV versus III, P = 0.07). Furthermore, a significant correlation between HMGA1 expression and MIB‐1 labelling index was observed (R = 0.368, P < 0.0002). Conclusions: These findings suggest that HMGA1 up‐regulation has an important oncogenic role in pituitary tumorigenesis, as well as being a novel molecular marker of tumour proliferation and invasiveness.