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Analysis of the Clinical Relevance of Histological Classification of Benign Epithelial Salivary Gland Tumours.

ABSTRACT:

Introduction

A vast increase in knowledge of numerous aspects of malignant salivary gland tumours has emerged during the last decade and, for several reasons, this has not been the case in benign epithelial salivary gland tumours. We have performed a literature review to investigate whether an accurate histological diagnosis of the 11 different types of benign epithelial salivary gland tumours is correlated to any differences in their clinical behaviour.

Methods

A search was performed for histological classifications, recurrence rates and risks for malignant transformation, treatment modalities, and prognosis of these tumours. The search was performed primarily through PubMed, Google Scholar, and all versions of WHO classifications since 1972, as well as numerous textbooks on salivary gland tumours/head and neck/pathology/oncology. A large number of archival salivary tumours were also reviewed histologically.

Results

Pleomorphic adenomas carry a considerable risk (5-15%) for malignant transformation but, albeit to a much lesser degree, so do basal cell adenomas and Warthin tumours, while the other eight types virtually never develop into malignancy. Pleomorphic adenoma has a rather high risk for recurrence while recurrence occurs only occasionally in sialadenoma papilliferum, oncocytoma, canalicular adenoma, myoepithelioma and the membranous type of basal cell adenoma. Papillomas, lymphadenoma, sebaceous adenoma, cystadenoma, basal cell adenoma (solid, trabecular and tubular subtypes) very rarely, if ever, recur.

Conclusions

A correct histopathological diagnosis of these tumours is necessary due to (1) preventing confusion with malignant salivary gland tumours; (2) only one (pleomorphic adenoma) has a considerable risk for malignant transformation, but all four histological types of basal cell adenoma can occasionally develop into malignancy, as does Warthin tumour; (3) sialadenoma papilliferum, oncocytoma, canalicular adenoma, myoepithelioma and Warthin tumour only occasionally recur; while (4) intraductal and inverted papilloma, lymphadenoma, sebaceous adenoma, cystadenoma, basal cell adenoma (apart from the membranous type) virtually never recur. No biomarker was found to be relevant for predicting recurrence or potential malignant development. Guidelines for appropriate treatment strategies are given.

SUBMITTER: Hellquist H

PROVIDER: S-EPMC6822986 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:IntroductionMinor salivary gland neoplasms of epithelial origin are rare in children and adolescents and most are not well documented, except for a few small series and case reports. This study represents a retrospective clinical analysis of nine cases of benign epithelial salivary gland neoplasms accessioned over a 35-year period at the Louisiana State University School of Dentistry and combines the data with well-documented cases from the English-language literature.MethodsA retrospective clinical analysis of nine cases of benign epithelial salivary gland neoplasms was performed over a 35-year period at the Louisiana State University School of Dentistry and combined with data of well-documented cases from the English-language literature.ResultsThe nine benign salivary gland neoplasms in patients aged 19 months to 18 years accounted for 2.3% of the Louisiana State University School of Dentistry accessioned salivary gland tumors. These nine cases comprised eight pleomorphic adenomas and one cystadenoma. There were 40 cases in the literature, of which 34 were pleomorphic adenomas. Combining the data for the 42 pleomorphic adenomas resulted in a mean age of 12 years with a 2.8:1 female predilection. The hard palate and/or soft palate were the most common site (69.1%). The average duration and size was 2.1 years and 2.4cm, respectively. Bone involvement occurred in seven cases. Wide local excision was the treatment most often employed. Cases followed for two years or more had a recurrence rate of 13.0%. The remaining seven neoplasms in the combined data comprised myoepithelioma, cystadenoma and sialadenoma papilliferum.ConclusionsA relatively long duration (2 years) of a submucosal mass in a minor salivary gland-bearing area with or without bone involvement occurring in a child or adolescent should raise the question of a possible salivary gland neoplasm. A pleomorphic adenoma is the most common benign salivary gland neoplasm in the first and second decade of life. Complete surgical excision affords the best chance of preventing recurrence for pleomorphic adenomas. The recurrence rate of pleomorphic adenomas with two or more years follow-up is 13.0%. Other types of minor salivary gland neoplasms are exceedingly rare and therefore data is sparse, precluding any valid conclusions.