Alpha-subunit immunoreactivity in plurihormonal pituitary adenomas of patients with acromegaly.

Twelve plurihormonal pituitary adenomas, removed surgically from 11 of 20 patients with acromegaly, were investigated. The mean age of the 11 patients was 45 yr. Seven patients with eight tumors were men. The tumors were immunostained for all known adenohypophysial hormones by the avidin-biotin-peroxidase complex (ABC) technique. All 12 adenomas were immunoreactive for growth hormone (GH) and alpha-subunit; prolactin (PRL) was detected in five tumors. Stains for the beta-subunits of glycoprotein hormones [thyroid-stimulating hormone (TSH), follicle-stimulating hormone (FSH), and luteinizing hormone (LH)] revealed immunopositivity for specific beta-subunits in ten adenomas. The close association between GH and alpha-subunit in pituitary tumors of acromegalic patients remains to be explained.     

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.     

Electron microscopical morphometry of pituitary adenomas. Comparison of tumours in acromegaly and hyperprolactinemia

By electron microscopical morphometry (point counting method) 4 groups of adenomas were compared in order to identify the source of prolactin in hyperprolactinemia. The 4 types of adenomas were characterized by the following features: Group I: acromegaly without hyperprolactinemia (GH positive and PRL negative on the immunohistochemical level); Group II: acromegaly with hyperprolactinemia and/or galactorrhea (GH positive and PRL positive on the immunohistochemical level); Group III: adenomas with hyperprolactinemia without acromegaly (GH negative and PRL positive on the immunohistochemical level); Group IV: adenomas with hyperprolactinemia without acromegaly (GH and PRL negative on the immunohistochemical level). Morphometry was performed in order to analyse the relative amount of the following cellular structures: nuclei, nucleoli, rough endoplasmic reticulum, Golgi fields, immature secretory granules, mature secretory granules, lysosomes, mitochondria, unorganized cytoplasm, and cellular membranes. Significant differences (Student t-test, Wilcoxon test; 2 p less than 0.05) were found for the following compartments: rough endoplasmic reticulum and Golgi fields in group III had significantly larger volumes than in group IV. The volume of secretory granules of group II and group IV was larger than of group III. The volume of mitochondria of group IV was larger than in group I, and it was larger in group I and group III than in group II. Despite these differences a distinctive morphometrical pattern of the different subgroups could not be established. The quantitative data are valuable for interpretation of high or low functional activity but not for differential diagnoses. Therefore, if only the source of PRL in hyperprolactinemia has to be identified, immunocytochemistry is the best and simpler method.(ABSTRACT TRUNCATED AT 250 WORDS)     

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.     

Somatotropic adenomas without acromegaly.

Seventeen somatotropic adenomas removed from patients without acromegaly were studied. Thirteen of them presented as a prolactinoma with amenorrhea and/or galactorrhea and elevated serum PRL levels. According to basal serum GH levels, the patients were divided into two groups, namely Group I: GH slightly elevated (n = 4) and group II: GH less than or equal to 5 micrograms/l (n = 13). The tumoral GH secretion was proved by immunocytochemistry in all cases and by intratumoral RIA, in vitro study and/or in situ hybridization in five of them. Pathological, clinical and biochemical relationships suggested two anatomoclinical aspects. In group I, the tumors were small, well-differentiated somatotropic adenomas with clinically silent GH hypersecretion. It is probably an early stage of the disease. In group II, the tumors were large with normal GH serum levels. They were poorly differentiated and secreted very low amounts of GH. In nine of them, PRL and/or PRL mRNA expression were also detected. These tumors do not secrete enough GH to increase serum levels and cause acromegaly. The somatotropic adenomas without acromegaly correspond to two anatomoclinical aspects of the disease.     

肢端肥大症患者垂体生长激素瘤切除术后身体组分的改变

目的探讨肢端肥大症患者病情活动期与缓解后身体组分的变化与生长激素(GH)、类胰岛素生长因子-1(IGF-1)水平的相关性。方法治疗前后患者做生长激素葡萄糖抑制试验(OGTT),测定GH谷值、空腹IGF-1水平;使用体脂分析仪测定身高、体质量、脂肪百分含量(fat%)、去脂肪量(FFM)和身体总水量(TBW)。结果活动期男性患者体重指数(BMI)和FFM显著高于正常对照,脂肪百分含量则显著低于后者;缓解后,患者GH谷值和IGF-1水平明显下降,BMI仍显著高于正常男性,而脂肪百分含量和FFM分别呈现增加和减少的趋势,与GH谷值和IGF1水平的降低显著相关。活动期女性患者与正常女性比较,BMI、FFM显著高于后者,而两者脂肪百分含量无显著差异;缓解后,患者FFM逐渐减少,与GH谷值显著相关,脂肪百分含量无明显变化。结论肢端肥大症患者身体组分与正常人相比差异显著。缓解后身体组分发生变化,与GH谷值、IGF-1水平密切相关。     

Amyloid in pituitary adenomas

71 surgically removed pituitary adenomas with amyloid deposits were studied by light microscopical and immunohistological means. In none of the adenomas was there a predominance of amyloid deposits. There were no correlations between the extent or pattern of the deposits with either age, immunohistological hormone content or localization. Our results do not support either of the theories about the origin of amyloid--whether mesenchymal or produced by adenoma cells--in pituitary adenomas.     

Plurihormonal pituitary adenomas

Plurihormonal adenomas of the pituitary, ie, tumors that engage in the production of unusual combinations of hormones, represent approximately 10% to 15% of all adenomas. Such tumors comprise in excess of 50% of adenomas in the setting of acromegaly and occur with somewhat greater frequency in childhood and adolescence than in adulthood. Eight percent are associated with multiple endocrine neoplasia, type I. The most common variant of plurihormonal adenoma produces growth hormone, prolactin, and one or more glycoprotein hormones, the most common being TSH. Clinical effects most often reflect the presence of growth hormone, and to a lesser extent, prolactin cells; expression of glycoprotein hormone production is rare. The tumors are more often macroadenomas (80%) than microadenomas (20%) and demonstrate gross invasion in 50% of cases. Plurihormonal adenomas may be ultrastructurally monomorphous, bimorphous, or trimorphous; thus, one morphologic cell type may elaborate several hormones.     

Alpha-subunit-producing pituitary adenomas

Summary Immunohistological techniques demonstrate the alpha-subunit of glycoprotein hormones in the majority of endocrine-inactive, undifferentiated pituitary adenomas and pituitary oncocytomas. In about one-fifth of endocrine-active adenomas, the alpha-subunit is produced in combination with either adrenocorticotropic hormone or prolactin, and it is found in combination with growth hormone in about half of those adenomas causing acromegaly.Pure alpha-subunit-producing, endocrine-inactive adenomas characteristically have small secretory granules that are destroyed by direct osmium fixation, but are well preserved after prefixation with glutaraldehyde. As only a few atypical prolactinomas show similar secretory granules, and as they display a positive reaction for the alpha-subunit only exceptionally, this ultrastructural feature can serve as a guide to differentiate such adenomas.     

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.     

Correlation between tumor vascularity and clinical findings in patients with pituitary adenomas

Angiogenesis generally plays an essential role in tumor growth and metastasis, and also influences the response to treatment in human malignant solid tumors. Even in nonmalignant tumors, angiogenesis is essential for tumor growth and invasion. In order to define the relationship between tumor vascularity and the clinical course in patients with pituitary adenomas, we quantified the vascularity in 47 pituitary adenomas and in 6 normal anterior pituitary glands obtained at autopsy using a computed image-analyzing system. We estimated two parameters, the vascular number and the area as the vascularity. Additionally, we calculated mean individual vessel size using the above two parameters. The relationships of tumor vascularity to clinical, endocrinological and histological findings was assessed. Factors considered included patient age and gender, preoperative medication, histological type, concentration of each hypersecreted pituitary hormone, maximum tumor size, cavernous sinus invasion, intratumoral hemorrhage, and immunohistological results of localization of vascular endothelial growth factor (VEGF). Vascularity was significantly higher in normal glands than in pituitary adenomas. However, there were no significant correlations between tumor vascularity and other clinical, endocrinological, or histological parameters, suggesting that increased angiogenesis is not essential for pituitary adenoma growth or invasiveness.     

Immunocytochemical localization of vimentin in stellate cells (Folliculo-stellate cells) of the rat, cat and rabbit pituitary pars distalis

Summary The occurrence of vimentin, a specific intermediate filament protein, has been studied by an indirect immunoperoxidase method in the anterior pituitary gland of adult rats, cats and rabbits of both sexes. In the three species studied, the immunoreaction product was detected in the cytoplasm of stellate-shaped cells scattered throughout the pars distalis. These stellate cells showed long cytoplasmic processes which could be seen between the secretory cells, and occasionally, encircling them. These processes sometimes reach the vasculo-connective septa. The marginal cells lining the anterior layer of the hypophyseal cleft of the rat and the cat pituitary glands also showed a positive immunoreaction. Finally, cyst or follicle-like structures lined by immunostained cells with basal processes could be observed in the anterior lobe of the rat, but not in that of the rabbit or the cat.These findings support the previously held view that folliculo-stellate cells and marginal cells of the anterior pituitary gland have a common nature and suggest that these cell types might be derived from glial neuroectodermic cells.     

Double pituitary adenomas: a series of three patients

Multiple pituitary adenomas may occur in up to 1.6-3.3% of patients with Cushing's syndrome. We report three patients with double pituitary adenomas detected at surgery. Two patients had Cushing's disease, but trans-sphenoidal exploration revealed a small prolactinoma in each. One prolactinoma also contained small numbers of basophils. Re-operation in both patients because of persistent Cushing's syndrome showed an ACTH-secreting micro-adenoma. The third patient with acromegaly had two macro-adenomas discovered in different parts of the gland at surgery: one plurihormonal and one null cell tumour. Careful evaluation of pre-operative MRI may not always detect more than one pituitary adenoma.     

Invasiveness of pituitary adenomas

528 biopsies from 396 pituitary adenomas were re-examined by light microscopy and checked for invasion of neighbouring tissues. The overall invasion rate was 41.9%. Highly differentiated ACTH-cell adenomas were invasive in 24.1%, undifferentiated mucoid-cell adenomas in 66.7%. The histological type of invasion was influenced by the adenoma type and by the invaded tissue. There was no obvious correlation between the adenoma type and the invaded tissue.