Nucleolar organiser regions in pituitary adenomas

Prognostic criteria in nonfunctioning pancreatic endocrine tumours

To identify prognostic subgroups among non-functioning (nonsyndromic) pancreatic endocrine tumours, a series of 61 tumours were analysed systematically for macroscopic, histopathological and immunohistochemical variables potentially predictive of malignancy. High-grade nuclear atypia, elevated mitotic rate and multifocal necrosis allowed us to separate 5 poorly differentiated carcinomas from 56 well differentiated tumours. Among the latter, 29 well-differentiated carcinomas showing gross local invasion or metastases were identified. Vascular or perineural microinvasion, Ki67 proliferative index > 2%, mitotic rate > or = 2, size > or = 4 cm, capsular penetration, nuclear atypia, lack of progesterone receptors and presence of calcitonin were among the variables correlated with malignancy. The first two were the most sensitive and specific. Their presence or absence was used in the 27 tumours lacking evidence of malignancy at the time of surgery to separate 11 cases with increased risk of malignancy (in 2 of which metastases developed during follow-up) from 16 cases with limited risk. The resulting four prognostic groups of non-functioning pancreatic endocrine tumours (limited- and increased-risk tumours, well-differentiated carcinomas and poorly differentiated carcinomas) showed distinct survival curves, which were significantly affected by vascular microinvasion, Ki67 proliferative index and metastases.

Incidental adenomas of the human pituitary gland

Using conventional histological technique, we investigated 44 adenomas (31 men, 13 women) incidentally found in 36 pituitaries (25 men, 11 women) obtained from 1,117 unselected autopsies. The overall incidence of adenomas was 3.2% (men, 3.8%; women, 2.4%) without any significant sex predominance. Size, age distribution, and histological appearances of these adenomas were similar to those previously reported by others. Statistical analysis showed that the adenomas had a predilection for occurrence at the anterior margin of the gland. We further investigated 33 available adenomas with immunohistochemistry using antibodies for various adenohypophyseal hormones, S-100 protein, and glial fibrillary acidic protein, of which 6 contained growth hormone, 3 contained growth hormone and prolactin, 7 contained prolactin, 6 contained follicle-stimulating hormone, 3 contained follicle-stimulating and luteinizing hormones, 2 contained thyroid-stimulating and adrenocorticotrophic hormones (separately), and 6 contained no adenohypophyseal hormones. None of adenomas revealed neoplastic proliferation of folliculostellate cells. To investigate tumor proliferation, nucleolar organizer regions were studied in 9 adenomas using the argyrophil method. The mean number per nucleus was slightly higher than that of corresponding, nontumorous adenohypophysis at a statistically significant level. No adenoma caused symptoms of adenohypophyseal hormone abnormalities.

Nucleolar organizer regions and glycoprotein-hormone alpha-chain reaction as markers of malignancy in endocrine tumours of the pancreas

The value of silver staining of nucleolar organizer regions (AgNORs) and human chorionic gonadotropin alpha-chain reaction (HCG-alpha) as markers of malignancy was investigated in 60 primary pancreatic endocrine tumours, 37 of which had metastasized at the time of surgery, and in one of which metastases developed 4 years after surgery. Assessment of AgNORs by digital image analysis revealed few but large AgNORs (mean number 2.5 +/- 1.1; mean area 0.32 +/- 0.1 microns 2) in the 22 benign tumours and many but small AgNORs (mean number 5.1 +/- 1.9, P < 0.05; mean area 0.18 +/- 0.09 microns 2, P < 0.01) in the malignant tumours. Quantification of the number of AgNORs per tumour cell nucleolus (AgNOR distribution score) showed that 96% (26/27) of tumours exhibiting at least 5% of cells with more than six AgNORs per nucleolus showed metastases either at the time of diagnosis or up to 4 years after surgery. HCG-alpha immunoreactive cells were present in 25/38 (66%) malignant tumours and in 4/22 (18%) benign tumours. Combined evaluation of AgNOR distribution and HCG-alpha scores showed a high positive predictive value of 96% in cases with a raised AgNOR distribution score irrespective of the HCG-alpha status. A good negative predictive value (81%) was, however, only obtained if both parameters, AgNOR distribution and HCG-alpha scores, were negative. Thus, investigation of AgNORs and HCG-alpha is helpful in predicting malignancy in a high percentage of pancreatic endocrine tumours.

Histochemical study of pituitary adenomas with Ki-67 and anti-DNA polymerase alpha monoclonal antibodies, bromodeoxyuridine labeling, and nucleolar organizer region counts

The growth potential of 65 pituitary adenomas was determined by histochemical analysis with Ki-67 and anti-DNA polymerase alpha monoclonal antibodies, bromodeoxyuridine (BrdUdR) labeling, and counts of argyrophilic nucleolar organizer regions (Ag-NORs). The mean proliferating cell indices (PCIs) determined by Ki-67 and anti-DNA polymerase alpha and the BrdUdR labeling index (LI) were generally very low [1.0 +/- 0.2%, 1.1 +/- 0.2%, and 0.5 +/- 0.1% (+/- SE), respectively]. Apart from adrenocorticotropic hormone-positive adenomas, which had significantly higher indices, there were no statistically significant differences in the indices among the other subtypes of pituitary adenomas. Recurrent tumors had higher Ki-67 and DNA polymerase alpha PCIs and BrdUdR LIs (3.6%, 4.2%, 1.4%) than primary tumors (0.8%, 0.8%, 0.3%; P less than 0.005). The number of Ag-NORs did not correlate significantly with any of the three indices. The mean number of Ag-NORs was higher in nonfunctioning adenomas than in functioning adenomas (2.04 vs 1.66, P less than 0.005); among prolactin-positive adenomas, those treated preoperatively with bromocriptine had more Ag-NORs than untreated tumors (1.75 vs 1.57, P less than 0.005). These results suggest that the Ki-67 and DNA polymerase alpha PCIs and the BrdUdR LI predict the growth potential of individual pituitary adenomas, whereas the number of Ag-NORs appears to correlate with hormone production rather than with the proliferative potential.

Glial fibrillary acidic protein (GFAP) expression and nucleolar organizer regions (NORs) in human gliomas

The frequency of nucleolar organizer regions (NORs) in each glioma tissue and the relation between the expression of glial fibrillary acidic protein (GFAP) and the frequency of NORs was investigated. The number of Ag-NORs per cell for glioblastoma multiforme was significantly higher than that for anaplastic astrocytoma (P less than 0.05) and that for astrocytoma (P less than 0.01). The number of Ag-NORs per cell for GFAP-positive cells was significantly lower than that for GFAP-negative cells in each histopathological grade (P less than 0.01). Moreover, the linear relationship was demonstrated between the Ag-NORs numbers of GFAP-negative cells and bromodeoxyuridine (BUdR) labeling indices. From these results, it is concluded that many GFAP-positive glioma cells may have low growth potential in glioma tissue and GFAP-negative cells may have a close relation to cell proliferation. The combination of immunohistochemical and silver colloid staining is a useful method for investigating the biological characteristics of brain tumors.

Rapid detection of proliferating potential in human brain tumors by nucleolar organizer region staining on squash preparations

Rapid detection of the proliferating potential of 37 human brain tumors was attempted using squash preparations stained by a silver colloid technique for argyrophilic protein associated with nucleolar organizer regions (AgNORs). Less than 1 h was required for staining. The mean number of AgNORs in cell nuclei of malignant or recurrent brain tumors (16 cases) including meningeal sarcoma, recurrent meningioma, recurrent craniopharyngioma, anaplastic astrocytoma, glioblastoma multiforme and metastatic brain tumor was 3.18, and the number for benign brain tumors (21 cases) including meningioma, neurinoma, pituitary adenoma, benign astrocytoma, ependymoma, and adenoma of lachrymal gland was 1.85. The former value was significantly greater than the latter value (P less than 0.001). These results indicate that quantitative analysis of AgNORs in brain neoplastic cells, using squash preparations, is useful to differentiate malignant from benign tumors within 1 h. Thus, this method provides rapid and useful information about the proliferative potential of human brain tumors even during operation.

Correlation between nucleolar organizer region score and bromodeoxyuridine labeling index in C6 glioma cell line

Correlation between the mean number of nucleolar organizer region-associated argyrophilic proteins (AgNORs) per cell and BrdU labeling index (LI), the percentage of S-phase cells, was investigated in vitro using rat C6 glioma cells under several different conditions such as increased concentration of fetal calf serum (FCS) in a stepwise manner in medium. In addition, the effect of dibutyryladenosine cyclic monophosphate (d-cAMP) on the mean number of AgNORs and the BrdU LI was examined. C6 glioma cells cultured with no FCS showed 5.1% BrdU LI and 3.46 AgNOR score. BrdU LI and AgNOR score of the cells cultured with 1% FCS were 26.5% and 6.25, respectively. Those with 5% FCS were 44.7% and 8.41, with 10% FCS; 49.8% and 10.85, and with 20% FCS; 48.4% and 10.64. Treatment of d-cAMP with 10% FCS induced morphological differentiation and reduced BrdU LI (9.4%) and AgNORs score (4.90), compared with C6 cells cultured in medium containing 10% FCS without d-cAMP. Thus, the BrdU LI and AgNOR score of the C6 cells cultured under several different concentration of FCS were shown to be well linearly related (r = 0.97) and both values were decreased with morphological alteration of C6 glioma cells in the presence of 1 mM d-cAMP.

Argyrophilic nucleolar organiser region counts and prognosis in pharyngeal carcinoma

The prognostic significance of argyrophilic nucleolar organiser regions (AgNORs) has been evaluated in biopsy specimens from 61 primary squamous and undifferentiated carcinomas of the pharynx prior to therapy. The univariate Kaplan-Meyer survival analysis showed a significant correlation between 3- and 5-year survival rates and the mean AgNOR number per tumour cell (P less than 0.001). No significant correlation was found between prognosis and patients age and sex, tumour location, clinical stage, histologic grade, extent of lymphocytic infiltration, HMFG-2 positivity of tumour cells and UCHL1, LN2, MB2 positivity of infiltrating lymphocytes. There was no significant association between AgNOR counts and tumour histologic grade or clinical stage. Multivariate survival analysis showed that only two variables were significantly correlated with prognosis: AgNOR counts (P less than 0.001) and the extent of lymphocytic infiltration (P less than 0.027). Our results indicate the prognostic value of AgNOR counts and suggest the use of this method as a significant parameter in the pretherapeutic assessment of the aggressiveness of pharyngeal carcinomas.

Cell proliferation in intracranial tumours: selective silver staining of nucleolar organizer regions (AgNORs). Application to surgical and experimental neuro-oncology

A novel tool in diagnostic and experimental pathology, the AgNOR-technique, which consists of visualization of ribosomal gene activity by selective silver staining, was applied to 144 cytological specimens of human tumours of the nervous system. The number of silver-stained nucleolar organizer regions (AgNORs) was correlated with the biological behaviour of the tumours investigated; low AgNOR number were observed in benign neoplasms such as meningiomas and schwannomas and higher AgNOR numbers in glioblastomas and metastases. The mean AgNOR number per cell was 3.15 in astrocytomas, 4.5 in anaplastic astrocytomas and 5.86 in glioblastoma multiforme. Benign and malignant lesions showed different distribution patterns of AgNORs, with few but centrally located AgNORs in benign, and multiple but scattered AgNORs in malignant tumours. AgNOR number per cell and AgNOR area revealed an inverse relationship (correlation coefficient -0.15, linear regression). In addition to the human tumours, two N-nitroso-N-ethyl-urea (NEU) induced tumors in BD-IX rats a mixed glioma (G-XIII) and a malignant schwannoma (N-XII), were investigated. Twelve G-XIII gliomas revealed homogenous AgNOR-counts (standard error of the mean less than 10%), with absolute values between the values obtained for human glioblastomas and metastases. Seven N-XIII subcutaneously transplanted schwannomas revealed higher AgNOR values than human schwannomas, but lower than experimental gliomas. It is concluded that the AgNOR method, as a technique for visualization of ribosomal gene activity, is valuable for assessing proliferative activity and malignancy in both diagnostic and experimental neuropathology.

Nucleolar organizer regions and post-operative survival in glioblastoma multiforme

Counts of argyrophil nucleolar organizer regions (AgNORs) have been proposed as a method of assessing tumour growth rate. AgNOR counts have been shown to correlate with histological grade in glial and some non-glial tumours but few studies have included data relating to clinical outcome. We have examined the relationship between tumour AgNOR counts and postoperative survival in a retrospective study of 54 patients with glioblastoma multiforme. The mean number of AgNORs per nucleus varied from 1.7 to 10.8 in biopsies from different patients and correlated with mitotic rate (P less than 0.01) but not with post-operative survival, which ranged from 2 days to 54 months with four patients still alive. AgNOR counts were inversely related to patient age (P less than 0.01) and older patients tended to survive for shorter periods (P less than 0.05). Although AgNOR counts are related to the rate of tumour cell division, they are not useful for predicting the post-operative survival of patients with glioblastoma multiforme.

Computer-assisted image analysis of nucleolar organizer regions (NORs): a pilot study of astrocytomas and glioblastomas

Computer-assisted image analysis was used to measure nucleolar organizer regions (NORs) of 22 astrocytomas and glioblastomas. Image analysis provides reproducible information about number and size of NORs together with further karyometric data, which can be compared and processed with other patient-related data. Our study exhibits a statistical relationship between number and size of NORs and malignancy of the measured gliomas.

Argyrophilic nucleolar organizer region proteins (Ag-NORs) in human brain tumors: relations with grade of malignancy and proliferation indices

Proliferation indices and mean number of silver-stained nucleolar organizer region-associated proteins (Ag-NORs) are compared in 65 brain tumors, including 34 gliomas, 8 meningiomas, 17 metastatic tumors, and 6 other tumors. Immunocytochemical investigations include labeling with the monoclonal antibody Ki-67 which identifies the whole growth fraction, and with a monoclonal antibody against bromodeoxyuridine (BrdUrd) which detects cells in the S phase of the cell cycle after in vitro incubation with BrdUrd. When all types of tumors are collectively considered, mean numbers of Ag-NORs did not correlate with Ki-67 and Brd-Urd labeling indices (LIs) and mitotic index. Among tumor subtypes, only meningiomas showed significant correlations between Ag-NOR counts, LIs, and malignancy. Mean number of Ag-NORs did not correlate with proliferation indices and tumor grade in low-grade and high-grade gliomas. However, recurrent high-grade gliomas showed a tendency to higher Ag-NOR counts than primary tumors. This study indicates that counting of Ag-NORs in paraffin sections is of limited value in tumor neuropathology. Correlations found in meningeal tumors should be substantiated in larger series.

Prognostic significance of nucleolar organizing regions (NORs) in carcinomas of the sigmoid colon and rectum

The prognostic significance of silver-binding nucleolar organizing regions (AgNORs) has been evaluated in tissue sections of biopsies taken from 70 primary adenocarcinomas of the colon sigmoid (n = 25) and rectum (n = 45) prior to their curative resection. A significant correlation between five-year survival rate and the mean AgNOR number per tumour cell (p less than 0.001) and the mean size of silver stained dots (p less than 0.05) was found according to the univariate Kaplan-Meier survival analysis. There was no significant relationship between AgNOR content and grade of malignancy, pT categories or pN categories. Multivariate survival analysis of covariates (Cox regression model) revealed a set of five variables that significantly influenced the patients' outcome: pN categories, AgNOR content, pT categories, maximum grade of malignancy and number of inflammatory cells. From the clinical and pathological parameters studied, pN and pT categories as well as the mean AgNOR number were the most important variables predicting death from colorectal carcinoma. Since the analysis of AgNORs can be performed on routinely processed paraffin-embedded tissue, this method may be of potential use in pretherapeutic assessment of the biologic aggressiveness of the disease.

Nucleolar organizer regions (NORs). Basic concepts and practical application in tumor pathology

The purpose of this investigation is to give an introduction to a novel method in tumor pathology, namely the Ag-NOR technique. The basis of this method is the argyrophilic staining of intranucleolar, non-histone proteins which are specifically associated with transcriptionally active sites of ribosomal DNA. They can therefore be considered as a marker for the protein synthesis and thus the proliferation rate of a given cell. The morphologic basis of the argyrophilic reaction is presented by metaphasic and interphasic tissue culture cells. The applicability of Ag-NOR technique to tumor pathology is exemplified by main results of three studies dealing with tissue sections of 65 meningiomas, whole organ sections of 50 renal carcinomas, and cytospin preparations of 30 urinary washout specimens. These studies document the considerable value of the Ag-NOR content for both, malignancy diagnosis and tumor grading. With the help of image analysis it can be shown that besides the mean number of Ag-NORs the mean area per Ag-NOR dot is of diagnostic significance. In conclusion the Ag-NOR technique is a simple inexpensive and accurate method which can be applied both to formalin fixed, paraffin-embedded tissue and cytologic specimens. As a marker of malignancy it is an invaluable new tool for the diagnostic pathologist.