Pleomorphic adenoma and adenoid-cystic carcinoma of salivary glands: immunohistochemical assessment of proliferative activity in comparison with flow-cytometric study

[DNA ploidy and proliferative activity in salivary gland tumours]

DNA ploidy and S-Phase fraction (SPF) of 279 salivary gland tumours were analysed using high-resolution DNA flow cytometry. All 229 benign neoplasms were diploid while 12 of 50 malignant tumours showed cell populations with aneuploid DNA content. The SPF values of diploid malignancies were significantly higher if compared with pleomorphic adenomas but did not differ from that of the zystadenolymphoma (Warthin tumour) group. While aneuploidy represents a distinct indicator of malignancy SPF values are of minor relevance for dignity assessment in salivary gland tumours.

PCNA, Ki-67 and p53 expressions in submandibular salivary gland tumours

Salivary gland tumours are uncommon with a broad heterogeneity. The most common benign tumour is the pleomorphic adenoma, whereas mucoepidermoid carcinoma and adenoid cystic carcinoma predominate among the malignancies. Most salivary gland tumours occur in the parotid, and consequently clinical and biological data are normally derived from this site. This work describes the expressions of PCNA, Ki-67 and p53 in 15 pleomorphic adenomas, 15 mucoepidermoid carcinomas and 15 adenoid cystic carcinomas of the submandibular gland. Our results showed that all pleomorphic adenomas were negative for p53 and Ki-67 with 66.6% being positive for PCNA. Conversely, p53 was positive in 53% of the mucoepidermoid carcinomas and in 20% of the adenoid cystic carcinomas. Ki-67 was expressed in 47.7% of the mucoepidermoid carcinomas and 40% of the adenoid cystic carcinomas. All malignant tumours were positive for PCNA. These results indicate that the proliferative rate analysed with PCNA and Ki-67 and the expression of p53 in pleomorphic adenoma and adenoid cystic carcinoma of the submandibular gland were similar to those described in the parotid and minor salivary glands. However, mucoepidermoid carcinomas showed higher expression of these markers than those of other salivary glands. This work is the first describing the expression of these immunohistochemical markers exclusively in submandibular salivary gland tumours.

Proliferative activity in oral salivary gland tumors: the role of PCNA and AgNOR assessed by a double staining technique

The aim of this study was to evaluate the role of PCNA and AgNOR in the assessment of salivary gland tumor proliferation using a double staining technique. Ten cases of pleomorphic adenoma (PA) and seventeen cases of adenoid cystic carcinoma (ACC) were examined. Numeric and morphometric parameters of AgNOR were evaluated and compared in PCNA-positive and PCNA-negative nuclei. There were statistically significant differences in AgNOR numbers, perimeters and contour indices between PCNA-positive and -negative nuclei in the PA samples. The ACC samples demonstrated significant differences only in the AgNOR areas. Our results show that in salivary gland tumors there is not always a relationship between proliferative activity evaluated by AgNOR numeric and morphometric parameters and PCNA immunostaining.

Flow cytometric analysis of DNA content in parotid tumor and its contiguous acini

To investigate the relationship between proliferative capacity of salivary gland cells in contiguous acini of parotid tumors and recurrent neoplasma, DNA contents of 30 fresh specimens of parotid were studied by using cytometry in tumors, normal and shallow or deep lobe acini of the masses. The results showed that the DI was 1.369, S% 16.95, PI 26.18 in malignant tumors; DI was 1.171, S% 12.41, PI 15.54 in recurrent pleomorphic adenoma; DI was 1.141, S% 12. 74, PI 13.07 in pleomorphic adenoma, DI was 0.999, S% 5.10, PI 8.00 in normal acini. Analysis of variance showed there was a significant difference (P < 0.01). The average DNA contents of shallow on deep lobe of contiguous tumors was 1.08 in DI, 10.65 in S%, 13.49 in PI in malignant tumor, 1.06 in DI, 8.96 in S% and 9.85 in PI in pleomorphic adenoma, which were all higher than in normal acini (P > 0.05). It was concluded that the levels of DI and S% of parotid tumor and its contiguous acini are related to degree of malignancy or recurrent condition of the tumors, suggesting contiguous acini of parotid tumors had the strong capacity of proliferation, which might play an important role in recurrent or malignant change of the parotid tumors.

Proliferating cell nuclear antigen and c-erbB-2 oncoprotein expression in adenoid cystic carcinomas of the salivary glands

BACKGROUND

Adenoid cystic carcinoma (ACC) of the salivary gland shows a variable clinical course. It would be helpful to discover reliable biologic markers in the management of patients with ACC.

METHODS

We examined proliferating cell nuclear antigen (PCNA) and c-erbB-2 oncoprotein expression on 30 cases of ACC of the salivary glands. The immunohistochemical results, and size, location, and histologic grade of the tumors were compared with the clinical outcome of the patients.

RESULTS

Mean PCNA positivity of ACCs was 15%, and was higher in solid than in cribriform/tubular areas. High PCNA value was significantly correlated with shorter disease-free and overall survival of the patients with ACC. c-erbB-2 overexpression was observed in only five cases, focally in cribriform/tubular areas. High histologic grade, which was determined by the presence of solid components, showed a trend toward shorter survival. Size and location of ACC were not associated with patient outcome.

CONCLUSIONS

The present study indicates that PCNA score may be one of the most useful prognostic factor of ACC.