Pleomorphic adenoma of the salivary glands: prospective clinicopathologic and flow cytometric study

DNA aneuploidy as a topographic malignant transformation pattern in a pleomorphic adenoma of long-term evolution: a case report

Introduction

We present a case of long-term evolution of a submandibular pleomorphic adenoma. There is little information about topographic malignant transformation patterns of pleomorphic adenomas.

Case presentation

We extensively analyze a giant submandibular mixed tumor of 25-year evolution in a 57-year-old Caucasian woman. Deoxyribonucleic acid ploidy was evaluated in different superficial and deep areas using flow cytometry analysis and correlated with pathological and immunohistochemical characteristics. Superficial areas exhibited a typical histological pleomorphic adenoma pattern and were deoxyribonucleic acid diploid. Deep samples showed deoxyribonucleic acid aneuploidy, atypical histological benign features and expression of markers involved at an early-stage of malignant transformation, such as tumor protein 53 and antigen Ki67.

Conclusion

These findings revealed that deep tumor compartments may be involved in the initial stages of malignant transformation. Deoxyribonucleic acid ploidy analysis may provide an additional diagnosis tool and indicate 'uncertain' areas that require careful study to avoid diagnostic errors. Larger studies are needed to confirm our results and to evaluate the usefulness of the technique.

Clinical manifestations of recurrent parotid pleomorphic adenoma

Objectives

This study was undertaken to confirm the clinical characteristics of recurrent pleomorphic adenoma (RPA), and to identify those factors that affect the development of malignant transformation (MT) from RPA.

Methods

The medical records of 270 patients, who were operated upon for parotid PA, were retrospectively reviewed. The pathologic specimens of a selected series of 23 patients were reviewed for histologic subtype and microscopic multi-nodularity.

Results

Mean age of initial operation in RPA without MT (RPA^-MT) group was significantly lower than that of primary PA group. Mean age of the revision operation in RPA with MT (RPA^+MT) group was significantly greater than that of RPA^-MT group. Mean interval from operation to recurrence shortened after each revision operation. The risk of MT and additional recurrence increased significantly with recurrence. In RPA^-MT group tumor recurrence occurred in 21.4% of patients despite a clear resection margin.

Conclusion

The risk factors for MT may be an age of over 45 yr and multiple recurrences. However, younger patients are more at risk of recurrence. A clear resection margin cannot guarantee a cure in RPA, and it seems that parotid pleomorphic adenomas slowly gain malignant characteristics after repeated recurrences.

Flow cytometric S-phase fraction contributes to diagnosis of diploid malignant salivary gland tumours

DNA ploidy studies on salivary gland tumours have shown that the proportion of aneuploid cases, although confined to the malignant entities, is considerably lower than for other solid malignancies. To analyse whether the S-phase fraction (SPF) may contribute to discrimination of diploid malignant from benign tumours, DNA flow cytometric data from 45 different malignant salivary gland tumours was compared with that of 121 pleomorphic adenomas. All benign tumours were diploid. Twelve malignant tumours contained aneuploid cell populations. The SPF values for diploid malignancies ranged between 0.9% and 11.0% (mean 3.9%), and between 0.5% and 7.9% (mean 2.7%) for pleomorphic adenomas. A 4% cut-off value gained statistical significance for discriminating diploid malignant tumours from pleomorphic adenomas (P<0.01). The sensitivity for SPF>4% was 46% and the positive predictive value was 40%. A sensitivity of 60% and a positive predictive value of 54% was achieved by combining aneuploidy and SPF>4%. These results show that DNA flow cytometry may contribute to diagnostic assessment in salivary gland tumours.

Prognostic relevance of cell proliferation in head and neck tumors

Cell proliferative activity has been extensively investigated in head and neck tumors. Ki67/MIB-1 immunostaining, tritiated thymidine or bromodeoxyuridine labeling indices, DNA S-phase fraction, proliferating cell nuclear antigen expression, potential doubling time and analysis of the nucleolar organizer region associated proteins (AgNORs) have shown significant correlation with prognosis in 4806 cases of tumors of the oral cavity, salivary glands, pharynx and larynx. However, this was not observed in 2968 other reported cases. Discrepancies may depend on various factors: the heterogeneity of the series, which include tumors from various anatomic sites and patients treated with different therapy, and the lack of standardization of methods for assessing cell proliferation. Furthermore, none of the methods currently applied can by themselves define the actual proliferative activity, as it depends both on the proportion of cells committed to the cycle (growth fraction) and the speed of the cell cycle. Indeed, the actual proliferative activity of a tumor could well be measured by the equation [PA = Ki67 or MIB-1 scores x AgNORs], as we did in pharyngeal carcinoma. Provided that large and homogeneous series are evaluated by standardized methods, cell proliferative activity can still be regarded as an inexpensive and reliable prognostic factor in head and neck tumors.

Synchronous tumours of the unilateral parotid gland: rare or undetected?

INTRODUCTION

Multiple tumours of the parotid gland with the same histological appearance may occur as synchronous unilateral tumours, but bilaterality has also been reported. Synchronous multiple unilateral parotid tumours with different histology remain rare.

METHODS

Between January 1988 and May 2002, a total of 341 patients underwent parotidectomy in our department. Medical charts were reviewed retrospectively for synchronous multiple unilateral tumours.

RESULTS

Fourteen patients had two or more tumours within the same specimen. The combinations encountered were two to four adenolymphomas (n=9), adenolymphoma plus pleomorphic adenoma (n=3), adenolymphoma plus MALT lymphoma (n=1), and pleomorphic adenoma plus acinic cell carcinoma (n=1). The outcome was clinical freedom from signs of tumour recurrence in any patient (mean follow-up = 51 months).

CONCLUSION

Synchronous multiple unilateral parotid tumours usually include two or more adenolymphomas and might occur more often than previously realized. The possibility of a concomitant carcinoma, and the prevention of recurrent tumours, may warrant a more radical surgical excision of the parotid gland, accurate intraoperative examination of the resected specimen, and routine histological evaluation of the entire specimen. Preoperative radiological investigation may further increase the chances of finding multiple parotid tumours.