Ultrastructural organization of nucleoli in benign naevi and malignant melanomas

Nucleolar Organizer Regions in Normal Skeletal Muscle and Benign and Malignant Rhabdomyoblastic Tumors

The silver staining of interphase nucleolar organizer regions (NORs) has been shown to have an important application in diagnostic histopathology for distinguishing some benign from malignant conditions. In this study, normal fetal and adult skeletal muscles and tissue from fetal and adult rhabdomyomas as well as rhabdomyosarcomas were stained with the silver method for NORs. The morphologic distribution of NORs in rhabdomyosarcomas was found to be very different from that in normal skeletal muscles. In addition, cases of rhabdomyoma were easily differentiated from rhabdomyosarcomas. Statistical analysis of data, from all cases, regarding the diameter of NORs and number per nucleus confirmed these observations.

Targeting the nucleolus for cancer intervention

The contribution of the nucleolus to cancer is well established with respect to its traditional role in facilitating ribosome biogenesis and proliferative capacity. More contemporary studies however, infer that nucleoli contribute a much broader role in malignant transformation. Specifically, extra-ribosomal functions of the nucleolus position it as a central integrator of cellular proliferation and stress signaling, and are emerging as important mechanisms for modulating how oncogenes and tumor suppressors operate in normal and malignant cells. The dependence of certain tumor cells to co-opt nucleolar processes to maintain their cancer phenotypes has now clearly been demonstrated by the application of small molecule inhibitors of RNA Polymerase I to block ribosomal DNA transcription and disrupt nucleolar function (Bywater et al., 2012 [1]). These drugs, which selectively kill tumor cells in vivo while sparing normal cells, have now progressed to clinical trials. It is likely that we have only just begun to scratch the surface of the potential of the nucleolus as a new target for cancer therapy, with "suppression of nucleolar stress" representing an emerging "hallmark" of cancer. This article is part of a Special Issue entitled: Role of the Nucleolus in Human Disease.

The value of PCNA and AgNOR staining in endoscopic biopsies of gastric mucosa

The aim of the present study was to examine the usefulness of the quantification of PC10-positive-cells and of Argyrophilic Nucleolar Organizer Regions (AgNORs) in gastric biopsies for the identification of gastric mucosal proliferative lesions. Fifty seven paraffin-embedded endoscopic biopsies were classified into four histologic groups: normal, inflammatory, dysplastic and neoplastic mucosa. The percentage of PC10-positive cells was determined by immunohistochemistry. The AgNOR parameters determined included the total number of all identifiable silver precipitations in the nucleus, the mean number of silver precipitations per cluster, and the presence of morphologically heterogenous silver precipitations. Group comparisons were performed using the Kruskall Wallis and Dunn non-parametric tests with a significance level of 5%. A discriminant analysis (followed by the jack-knife procedure) was performed using the three AgNOR parameters plus the percentage of PCNA-positive cells as the independent variables and histological groups as the dependent variable. All three AgNOR parameters, as well as the percentage of PCNA-stained nuclei, showed their highest values in the carcinoma group. However, no good differentiation among the four histologic groups was obtained using only one of these parameters, since there was always considerable overlap among them. By combining all the parameters in a linear discriminant analysis, we obtained a correct classification in 48 out of 57 cases. Within the classification errors there was only one false positive carcinoma, which was in fact a dysplasia and only one false negative carcinoma erroneously classified as dysplasia. The number of cells with heterogenous AgNORs was the most important parameter for the discriminant analysis. No correlation between PCNA values and the AgNOR parameters could be found, thus indicating that they do not represent the same phenomenon in the cell cycle. We concluded that the use of a combination of various proliferation parameters in a linear discriminant analysis may be helpful for differentiating gastric mucosal lesions. The peculiar AgNOR morphology is an important variable which should be taken in consideration in quantitative studies. PCNA and AgNORs seem to represent different physiological phenomena in the cell cycle.

NO38 expression and nucleolar counts are correlated with cellular DNA content but not with proliferation parameters in colorectal carcinomas

AIMS

To investigate the expression of nucleolar protein NO38, to determine the numbers of nucleoli per cell, and to examine the relations of these nucleolar parameters to tumour DNA index, total cellular DNA content, S phase fraction, and Ki67 labelling index.

METHODS

36 colorectal tumours and 14 normal mucosas were studied. An anti-NO38 monoclonal antibody, 31A12, and flow cytometric analysis were used to detect expression of NO38 by means of a biotin-streptavidin-FITC (fluorescein isothiocyanate) staining method. Nucleolar counts were determined using fluorescence microscopy. Flow cytometry was used to determine tumour DNA indices and the sizes of the S phase fractions. Ki67 labelling indices were determined from tissue sections stained immunohistochemically with the MIB-1 antibody against the Ki67 nuclear protein.

RESULTS

Generally, tumour cell nucleoli were larger and more irregular in shape compared with nucleoli in normal mucosal cells. DNA aneuploid and diploid tumours expressed 2.8 and 2.1 times more NO38 than normal mucosa. The mean (SD) values for nucleolar counts were higher for the DNA aneuploid tumours (3.81 (0.93)) than the diploid tumours (2.62 (0.38)) and normal mucosa (2.34 (0.37)). NO38 expression and numbers of nucleoli correlated significantly (r = 0.52, p = 0.01). There were, however, no significant correlations between these nucleolar parameters and either the sizes of tumour S phase fractions or Ki67 labelling indices. Cell cycle resolved expression of NO38 in tumours and normal mucosa demonstrated that expression increased approximately in proportion to the DNA content throughout the cell cycle. In aneuploid tumours, NO38 expression was 43% and 98% higher in S and G2 phases, respectively, compared with the G1 phase. Sorting of these populations revealed that the nucleolar count also increased as the DNA content increased but by only 29% and 47% in S and G2, respectively. Apoptotic cells lacked NO38.

CONCLUSIONS

NO38 expression is higher in tumours than in normal mucosa owing to the increased DNA content and larger nucleoli in tumours; expression increases proportionally with DNA content as cells progress through the cell cycle from G1 through S and G2. However, NO38 expression does not correlate with the tumour S phase fraction or Ki67 labelling index and is lost during apoptosis. Also the results suggest that nucleoli grow in size during the cell cycle, which would account for the doubling of NO38 expression from G1 to G2, as the nucleolar count increased by only 47%.

Prognostic value of nucleolar organizer regions in neuroendocrine tumours of the lung

The value of the number and size of the nucleolar organizer regions (NORs) as prognostic indicators in human neuroendocrine lung tumours was evaluated in a quantitative study of 57 cases, including 33 small cell carcinomas (SCLCs), 9 well-differentiated neuroendocrine carcinomas (WDNECs) and 15 "classic" carcinoids. NORs were visualized on paraffin sections by an argyrophilic technique (AgNOR) and measured by automatic image analysis. In each case, the mean number and area of AgNORs were evaluated; the results were compared with clinical follow-up and survival. AgNOR values for both number and area were significantly higher in SCLCs than in WDNECs and carcinoids. WDNECs had insignificantly higher AgNOR values than carcinoids. Among SCLCs, AgNOR values of the oat cell subtype and the intermediate cell subtype did not differ significantly. Regardless of the histological tumour type, AgNOR values strongly correlated with prognosis, with more and larger AgNORs indicating a more progressive clinical course. In the present study we demonstrate for the first time that the biological behaviour of neuroendocrine lung tumours is correlated with the number and size of AgNORs. Thus the measurement of AgNORs may serve as an additional prognostic indicator in these neoplasms, particularly in the separation of SCLCs from WDNECs with a more favourable prognosis.

Importance of interphase nucleolar organizer regions in tumor pathology

The importance of the distribution of silver-stained nucleolar organizer regions (Ag-NORs) in interphase nuclei for diagnostic and prognostic purposes in tumor pathology has been reviewed. The available data demonstrated that interphase Ag-NOR evaluation may be of help in distinguishing malignant from hyperplastic or normal cells. On the other hand, there is increasing evidence that a relationship exists between the quantity of interphase Ag-NORs and the prognosis of malignant tumors: the greater the number of interphase Ag-NORs, the worse is the prognosis. This can be explained by the observation that the interphase Ag-NOR quantity is strictly related to the cell proliferation rate. The procedures used for the measurement of the interphase Ag-NOR quantity are also critically discussed.

Classic, atypical, and anaplastic meningioma: three histopathological subtypes of clinical relevance

This study correlates the histopathological classification of meningiomas with clinicopathological features of biological activity. A retrospective evaluation of 1799 surgical specimens of meningiomas from 1582 patients was made. The classic histopathological type, atypical meningiomas defined by increased cellularity and at least five mitotic figures in 10 high-power fields, anaplastic (malignant) meningiomas, and hemangiopericytic or papillary meningiomas were seen in 87.6%, 7.2%, 2.4%, and 2.8% of operations, respectively. The rates of recurrence in surgically treated patients with classic, atypical, anaplastic, and hemangiopericytic or papillary meningiomas were 6.96%, 34.6%, 72.7%, and 68.2%, respectively. The extent of surgery and the tumor size and site were studied in detail in 252 tumors of all histopathological types. Recurrences were rare in classic meningiomas after complete resection, whereas atypical and anaplastic tumors recurred after complete resection much more frequently. Classic meningiomas, hemangiopericytomas, and papillary meningiomas were smaller at surgery than atypical and malignant meningiomas. Atypical and malignant tumors were operated on more often in falcine and lateral convexity regions than were classic meningiomas. To support the authors' subjective categorization by a quantitative parameter related to proliferation, 112 meningiomas comprising all histopathological subtypes were investigated for staining of argyrophilic nucleolar organizer region proteins (Ag-NOR's). The Ag-NOR counts showed significant differences between classic, atypical, and anaplastic tumors but no significant differences between primary and recurrent tumors. Hemangiopericytomas and papillary meningiomas had lower Ag-NOR values than anaplastic meningiomas. A correlation of Ag-NOR numbers with the authors' histopathological scale of malignancy supports the introduction of atypical meningiomas with intermediate biological behavior on the classification scale between classic and anaplastic meningiomas. Overlapping of Ag-NOR numbers among all groups of malignancy may restrict the prognostic value of Ag-NOR counting in the individual case.

Silver-stained nucleolar organizer proteins in urothelial bladder lesions. A morphometric study

The diagnostic value of image analysis of silver-stained nucleolar organizer regions (AgNORs) has been investigated in 170 urothelial bladder lesions obtained by transurethral biopsies in the same number of patients. According to the WHO classification 25 specimens showed a flat non-invasive growth pattern with simple hyperplasia or mild dysplasia (H/D1 = 10), as well as moderate (D2 = 10) to severe atypia (Cis = 5). 135 samples were of papillary and/or infiltrating type including polypoid cystitis (pC = 5), true papillomas (G0 = 7), and carcinomas of different malignancy grade (G1 = 30, G2 = 55, G3 = 38). 10 biopsies served as normal controls. Benign non-neoplastic urothelium (controls, H/D1, pC) exhibited few but large AgNORs (mean number [MNN] = 3.3 +/- 0.5, mean area [MNA] = 0.29 +/- 0.08 micron 2), whereas carcinomatous lesions (Cis, G1-G3) showed numerous small silver-stained dots within their nuclei (MNN = 6.9 +/- 1.1; MNA = 0.12 +/- 0.04 micron 2). Both parameters, MNN and MNA, were inversely correlated (r = -0.69, p less than 0.001); their quotient (NQ = MNN/MNA) revealed a clear cut difference in the AgNOR content of benign (control, H/D1:NQ = 12.8 +/- 2.5) and moderate to severe atypical flat urothelial lesions (D2, Cis: NQ = 44.2 +/- 12.8, p less than 0.001). This parameter also discriminated between G1 (NQ = 40.7 +/- 17.3), G2 (NQ = 57.5 +/- 18.8), and G3 carcinomas (NQ = 79.0 +/- 21.8, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Expression of interphasic nucleolar organizer regions in normal, dysplastic and neoplastic colorectal mucosa

Silver-binding nucleolar organizer region (Ag-NOR) expression in interphasic nuclei was studied in normal, dysplastic and neoplastic colorectal mucosa at the light microscope level and by means of an image analyser (IBAS II). Both methods showed a progressive increase in the mean number of Ag-NOR sites per nucleus from mild dysplasia to invasive carcinoma. Ag-NOR counts differed significantly in the various classes of lesions (P less than 0.001), except between moderate and severe dysplasia (P greater than 0.05). Severe dysplasia showed a mean number of NORs lower than that for invasive carcinoma though an overlap in the respective frequency distributions was observed. The mean of the variances of the mean dot areas per cell nucleus (pooled variance) also showed a step-wise increase from normal to neoplastic lesions, indicating a greater variability in NOR size as a characteristic of malignant cells. A similar increase was observed in the percentage of nuclear area occupied by Ag-NORs. The mean area per silver-stained dot was also measured in the different classes of lesions by IBAS II. Data obtained showed no significant differences among the values. In conclusion, the wide overlap between the frequency distributions does not allow consideration of the Ag-NOR count alone to be a reliable marker of malignant transformation in a single cell. It appears that the study of Ag-NOR number needs to be evaluated together with dot anisometry in order to be a useful criterion in distinguishing the biological behaviour of neoplastic lesions in colorectal mucosa.

Ultrastructural discrimination between malignant melanomas and benign nevocytic nevi using high-resolution image and multivariate analyses

Prompted by the well-known difficulties of reliable and objective histologic differentiation between initial malignant melanoma (MM) and benign nevocytic nevi (NN), ultrastructural high-resolution image and multivariate analyses were evaluated for their diagnostic efficiency. Thirty-seven different features describing morphometry (area, circumference, and shape factor), amount of heterochromatin and euchromatin, chromatin homogeneity, and presence of smaller dark chromatin aggregations were determined by a MICROVAX 3500 computer in each of 1840 intraepidermal melanocytic nuclei of 17 MM and 20 NN. A strategy for the classification of cases based on the identification of markedly atypical melanocytic cells (MACS) was developed. MACS, selected in multivariate analysis with a linear combination of the eight most important features for cell classification, were found in 39.4% of the melanoma cells, but only in 0.3% of nevocytic nevus cells. The presence of MACS allowed a clear differentiation between MM and NN. All cases of MM had more than four MACS, whereas 17 cases of nevocytic nevi were MACS negative, and in each of the remaining three cases only one MAC was present. The percentage of MACS detected within intraepidermal parts of MM by using computerized high-resolution image analysis was found to be a highly efficient diagnostic marker. The new classification strategy has the potential of saving considerable time in subsequent studies, because preselected sampling and the calculation of only a few criteria have proven sufficient for correct classification of malignant melanomas.

The impact of nucleolar organizer regions for the lymph node spread and prognosis of invasive ductal mammary carcinoma

In primary tumours of 40 patients with invasive ductal carcinomas the significance of nucleolar organizer regions (NORs) for metastatic spread to the axillary lymph nodes and for the prognosis was assessed. Silver-stained tissue sections were investigated by means of semiautomated image analysis. The nucleolar organizer regions of 100 tumour cell nuclei per specimen were measured. The number as well as the area of the NORs were evaluated together with morphometrical and DNA features, histopathological and clinical data. By means of multivariate discriminant analysis, significant differences between tumours of 20 node-negative and 20 node-positive patients could be found. The mean number of NORs was significantly higher in patients with lymph node metastases (p = 0.0059), whereas the mean area was significantly lower in node-positive patients. By using the NOR number as the only parameter both groups were classified with an overall efficiency of 95%. There was also a significant difference between long-term and short-term survivors by considering the mean number of NORs, but the Auer-type, the 2 cDl value, and the DNA-grade of malignancy were of better predictive value. Within the group of node-negative patients the NOR number was most suitable for distinguishing between good and poor prognosis, whereas within the group of node-positive patients once more the DNA parameters played the most decisive role for predicting prognosis. With regard to the small number of patients the results have to be considered as preliminary. Further investigations in a more extensive population are necessary.

Nucleolar ultrastructure in low- and high-grade non-Hodgkin's lymphomas

Transmission electron microscopy was used to study the ultrastructure of nucleoli in seven high- and seven low-grade non-Hodgkin's lymphomas. Nucleoli with a single large fibrillar centre were predominantly seen in the low-grade group, while the majority of nucleoli in high-grade lesions contained several small fibrillar centres of approximately equal size. A third type of nucleolar appearance was identified, with a large central fibrillar centre surrounded by numerous small 'satellite' fibrillar centres. This nucleolar configuration was the least common but was more often seen in low-grade than in high-grade lymphomas. The mean fibrillar centre cross-sectional area was determined for each group and measured 278,800 nm2 for low-grade non-Hodgkin's lymphomas and 62,507 nm2 for high-grade lymphomas (P less than 0.001). These results show that fibrillar centre size and morphology correlates with grade of non-Hodgkin's lymphoma and may reflect differences in ribosomal deoxyribonucleic acid transcription.

Morphometry of nucleoli as an indicator for grade of malignancy of bladder tumors

To establish a new indicator for the classification of human urinary bladder cancers, the nucleoli of normal epithelial and neoplastic cells were analyzed, using morphometric techniques. By electron microscopy, the nucleolar profiles of cells from grade 2 and 3 transitional cell carcinomas were often small and irregular. Morphometry showed that the nucleolar volumes, nucleolar/nuclear volume ratios, volume densities of various nucleolar components, and the numbers of fibrillar centers (FCs) altered significantly with an increase in tumor grade. In particular, an increase in FC numbers in the nuclei of higher grade tumors was associated with a decrease in individual volume. The number of FCs in intact urothelial cells obtained from patients with bladder tumors is significantly larger than in the normal urothelial cells. This may be related to the multicentric origin of bladder cancers. These results suggest that morphometric analysis of nucleoli is useful in evaluating the degree of differentiation and invasive capacity of human bladder tumor cells. In particular, the number and individual volume of FCs may be an indicator of tumor malignancy.

The value of nucleolar organizer regions in uveal melanoma. The Collaborative Ocular Melanoma Study Group

Silver staining of nucleolar organizer regions is an objective method for evaluating the malignancy of a variety of tumors. We studied 126 ciliochoroidal melanomas, three coincidental nevi that occurred in eyes with melanomas, and one magnocellular nevus collected from the Collaborative Ocular Melanoma Study to determine the effectiveness of the silver-stained nucleolar organizer region technique in assessing the malignant potential of these tumors. Malignant lesions demonstrated higher mean silver-stained nucleolar organizer region counts (4.347) than benign nevi (1.855) (P less than or equal to .0001). Among malignant melanomas, mixed-cell melanomas had slightly higher counts than spindle-cell melanomas (P less than or equal to .0001), but this difference was not important clinically. Results were also compared to other histopathologic variables, which disclosed correlation of silver-stained nucleolar organizer regions with mitoses and tumor size. Comparison with computerized cytomorphometric analyses of prognosis also disclosed significant correlation. This technique may prove to be a useful adjunct in the assessment of malignancy and treatment response of uveal melanomas.

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.

Diagnostic value of silver-stained interphasic nucleolar organizer regions in breast tumors

Seventy-six specimens of normal breast tissue and benign and malignant breast lesions were studied to assess the mean area occupied by silver-stained proteins of the nucleolar organizer regions (MNORA) of the nucleolus. The assessment was performed with a computer-assisted image analyzer. The results indicate that only 30% of malignant lesions have a MNORA value greater than that of normal breast tissue or benign lesions. On the other hand, MNORA values of ductal carcinoma in situ were significantly greater than those of epitheliosis (papillomatosis). MNORA values were also significantly different in grade I and grade III invasive ductal carcinomas, the latter exhibiting the highest MNORA values of all the cases observed. Evaluation of MNORA values may therefore help in differentiating benign epithelial proliferations from ductal carcinomas in situ. Furthermore, because there is evidence that MNORA values are indicative of the cell duplication rate, MNORA values may ultimately be considered an objective prognostic parameter in addition to grading for invasive ductal carcinomas.

Molecular biology and respiratory disease. 3. Evaluation of nucleolar organiser regions in pulmonary pathology

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Relationship between intraepithelial neoplasia of the cervix and the size and number of nucleolar organizer regions

A silver colloid technique was applied to 18 colposcopic biopsies of the cervix. These comprised 7 cases of cervical intraepithelial neoplasia I (CIN I), 5 cases of CIN II, and 6 cases of CIN III. The nucleolar organizer regions subsequently visualized (AgNORs) were enumerated using an oil immersion lens. The maximum diameters of the AgNORs and aggregates thereof were measured, by hand, from carefully calibrated monochrome photographs. The mean numbers of AgNORs subsequently identified steadily increased, whereas the mean sizes of AgNORs decreased from CIN I to CIN III. In CIN I the mean AgNOR number was 2.3 (range 1.8-3.4) and the AgNOR mean maximum diameter (Dmax) was 1.28 microns (range 0.75-1.75). In CIN II the mean number was 3.5 (range 3.1-4.6) and the AgNOR Dmax was 0.98 micron (range 0.9-1.18). In CIN III the mean number was 4.7 (range 4.0-6.1) and the Dmax was 0.62 micron (range 0.51-0.9). CIN III could be distinguished from CIN I and CIN II on the basis of AgNOR sizes, and an inverse relationship between AgNOR numbers and sizes was established.

Sequential demonstration of antigens and AgNORs in frozen and paraffin sections

A technique has been designed which enables the sequential demonstration of nucleolar organizer regions (NORs) and various antigens, in both frozen and paraffin wax-embedded sections. The NORs were demonstrated by the standard argyrophil (AgNOR) method and the antigens were shown by either immunoperoxidase (PAP) or immunoalkaline phosphatase (alkaline phosphatase-anti-alkaline phosphatase or avidin-biotin-alkaline phosphatase) methodology. Clear, reproducible results were obtained and AgNOR sites were enumerated with ease. It is suggested that the sequential method may be of great use in the evaluation of AgNOR numbers in neoplasms, where cell populations are heterogeneous. Cell populations may be demarcated with accuracy prior to the counting the AgNORs.

The silver-stained proteins of interphasic nucleolar organizer regions as a parameter of cell duplication rate

The relationship between interphasic silver-stained proteins of the nucleolar organizer regions (Ag-NOR proteins) and cell replication rate has been studied in 13 established neuroblastoma cell lines. The quantity of Ag-NOR proteins was measured in silver-stained cells by means of an automated image analyzer. The results indicated that the amount of Ag-NOR proteins is strictly proportional to the proliferative activity of the cells. Cell lines with a difference of only 4 h in doubling time were characterized by a statistically significant difference in Ag-NOR protein amount. The Ag-NOR protein quantity can therefore be used as a parameter for evaluating the cell proliferation rate.

How should we count AgNORS? Proposals for a standardized approach

There is interest currently in the AgNOR technique, for NOR-associated proteins. In some cases, this technique enables the distinction to be made between certain grades of malignancy and may enable prognostic assessment. This paper attempts to suggest a standardized means for the enumeration of NORs in histological sections. Attention should be paid to rigorous technique and careful resolution of intranucleolar AgNOR dots. The timing of the reaction and fixation methods are also most important.

Benign conjunctival melanocytic lesions. Clinicopathologic features

The common acquired conjunctival nevus usually undergoes progressive maturation and only exceptionally gives rise to conjunctival melanoma. Pure junctional nevi are rare except in childhood. Histologically, however, a junctional nevus may be indistinguishable from primary acquired melanosis (PAM) with atypia, a condition of middle-aged and elderly individuals that has a tendency to evolve into melanoma. Nevi in adolescents may attract a vigorous lymphocytic response and may cause clinical and histologic confusion with other entities, particularly a regressing nodule of melanoma that occurs predominantly in adults. Rarely, congenital conjunctival nevi are identified, sometimes in patients with adjacent congenital nevi of the eyelid. A variety of unusual nevi, including balloon-cell nevi, Spitz nevi, epithelioid cell nevi, dysplastic nevi, recurrent nevi, episcleral melanosis and the nevus of Ota, blue and cellular blue nevi, melanocytoma, and composite or mixed nevi all may be identified in the conjunctiva. Concepts of histogenesis as well as the clinical, light microscopic, and ultrastructural features of these and other benign pigmentary conditions of the conjunctiva are described.

Computer-assisted image analysis of silver staining in normal and leukemic bone marrow

Computer-assisted image analysis was used to quantitate the amount of silver staining in interphase nuclei of bone marrow cells from acute lymphocytic leukemia (ALL) patients. When we compared the data obtained for the interphase nuclei with that obtained for the metaphase spreads, we found a strong correlation between the fraction of bone-marrow metaphases stained positively with silver, the average number of silver-positive nucleolus organizer regions per metaphase, and the amount of silver staining in the interphase nuclei. Computer-assisted image analysis of interphase nuclei can be used, therefore, to differentiate normal from ALL bone-marrow samples.

Correlation between NOR sizes and numbers in non-Hodgkin's lymphomas

A series of 36 cases of non-Hodgkin's lymphomas (NHL) has been studied by means of the argyrophil (AgNOR) method for nuclear organizer regions (NORs). Morphometric analysis of highly magnified photographic images of light microscope preparations of the AgNORs was performed by means of an interactive image analysis system. It was observed that in the low-grade specimens (where NORs are less frequent than in those of high-grade histology), the AgNOR sites were highly significantly (P less than 0.001) larger than in high-grade NHL. In the low-grade lymphomas, the AgNOR maximum diameter (Dmax) ranged from 0.7 to 1.7 micron 2 (mean 1.11 micron 2) and area ranged from 0.48 to 1.99 micron 2 (mean 1.11 micron 2). In contrast, in the high-grade specimens, Dmax was from 0.33 to 0.51 micron (mean 0.41 micron) and the area ranged from 0.082 to 0.19 micron 2 (mean 0.13 micron 2). Thus, a well-defined inverse relationship was observed between AgNOR numbers and their sizes. There was total separation between low- and high-grade values in this series. This light microscope technique offers some advantages over ultrastructural morphometry of interphase NORs (fibrillar centres).

Nucleolar organizer regions in melanocytic dysplasia and melanoma

Using silver (Ag) staining to demonstrate nucleolar organizer region-associated proteins (AgNORs), pigmented naevi exhibiting features of melanocytic dysplasia have been examined and compared with benign intradermal and compound naevi and with malignant melanomas. A highly significant difference was found between the numbers of AgNORs demonstrated in benign naevus cells and atypical melanocytes and in malignant melanocytes, suggesting that this technique may have a role in differentiating between difficult melanocytic lesions.

Interphasic nucleolar organizer region distribution as a diagnostic parameter to differentiate benign from malignant epithelial tumors of human intestine

The distribution of the interphasic nucleolar organizer regions (NORs) has been investigated in five hyperplastic polyps, five adenomatous polyps and fifteen colonic adenocarcinomas. The study was performed using electron microscopy and paraffin-embedded sections stained for Ag-NOR proteins. Malignant tumor cells were characterized by a large number of NORs which were small in size and showed a scattered distribution. Nuclei of both types of polyp had only a small number of large-sized NORs in a clustered distribution. In two adenomatous polyps, cells were also observed with an NOR distribution pattern intermediate between that of frankly benign and malignant lesions.