Minor salivary gland tumors of the oral cavity: a case series with review of literature

Myoepithelioma of the Palatal Minor Salivary Gland: A Case Report

Myoepithelioma is an uncommon benign tumor of the orofacial region arising from the salivary glands. These tumors are composed of specifically myoepithelial cells lacking ductal differentiation and were initially considered as a type of pleomorphic adenoma. Though they commonly arise from the parotid gland, there are a few cases that emerge from the minor salivary glands of the palate and oral cavity. Myoepitheliomas resemble many other tumors arising from the palate including pleomorphic adenoma. This report depicts a case of myoepithelioma of the minor salivary gland of the palate in a 23-year-old patient and the successful management of the lesion.

Intraoral Minor Salivary Gland Tumors: A Retrospective, Clinicopathologic, Single-Center Study of 432 Cases in Japan and a Comparison with Epidemiological Data

BACKGROUND

Intraoral minor salivary gland tumors are relatively rare lesions with histological subtypes not commonly found in major salivary glands. This study aimed to retrospectively evaluate the clinicopathologic features of intraoral minor salivary gland tumors from the Tokyo Dental College Hospital, Japan, and compare them with findings from other epidemiological studies.

METHODS

We conducted a retrospective clinicopathologic evaluation of 432 cases of intraoral minor salivary gland tumors [161 male (37.3%) and 271 female (62.7%) patients; mean age: 52.5 and 48.6 years for males and females, respectively; age at diagnosis: 7-87 (mean: 50.1) years] from the Tokyo Dental College Hospital between 1975 and 2022, including 283 benign tumors (65.5%) and 149 malignant tumors (34.5%).

RESULTS

The most common benign tumor was pleomorphic adenoma (n = 239), whereas mucoepidermoid carcinoma was the most common malignant tumor (n = 74). The mean age of patients with benign and malignant tumors was 48.4 and 53.2 years, respectively, with patients with malignant tumors being significantly older (P = 0.0042). The mean age of patients with malignant tumors was significantly higher in males (56.7 years) than in females (50.9 years) (P = 0.0376), although the mean age of patients with benign tumors did not differ by sex. Tumors were commonly located in the palate [250 cases (57.9%)]. Benign tumors were more frequent in the palate, upper lip, and buccal mucosa, whereas malignant tumors were more frequent in the palate, floor of the mouth, buccal mucosa, and retromolar area.

CONCLUSIONS

Understanding the features of intraoral minor salivary gland tumors is useful for diagnosis. Our study provides important epidemiological data (patient differences in age at occurrence, sex, and site of origin) that will inform clinicians and researchers.

Expression of PLAG1, HMGA1 and HMGA2 in minor salivary glands tumours

Background

Diagnosis of minor salivary gland (MSG) tumours is often difficult, due to the scarce tissue obtained from bioptic excision and complex histopathological differential diagnosis. In our study we performed an immunohistochemical analysis of PLAG1, HMGA1 and HMGA2 on a series of MSG tumours, in order to develop a new helpful diagnostic panel.

Methods

A retrospective series of 17 surgical specimens of MSG tumours were analysed for the expression of PLAG1, HMGA1 and HMGA2. Three control cases were enrolled and analysed. An intensity and percentage-based approach was performed, creating a combined score panel.

Results

PLAG1 facilitate the diagnosis of benign tumours, discriminating it from malignant histotypes, with a defined cut-off value. Similarly, HMGA1 is significantly higher in benign histotypes than in malignant ones. HMGA2 in our series, did not reveal any association in identifying benign from malignant histotypes.

Conclusions

In this study we assessed the diagnostic role of PLAG1, HMGA1 and HMGA2 immunohistochemical analysis. The score panel facilitate histopathological diagnosis of these rare tumours, helping to distinguish benign tumours from malignant ones and ameliorating the differential diagnosis of specific histotypes.

Clinical Outcome of Minor Salivary Gland Cancers in the Oral Cavity: A Comparative Analysis With Squamous Cell Carcinomas of the Oral Cavity

Purpose: Salivary gland cancer (SGC) in the oral cavity is not common and has been less studied in comparison with oral squamous cell carcinoma (SCC). This study aimed to identify the clinical characteristics and outcomes of SGC in the oral cavity compared with oral SCC.

Methods: The medical charts of the patients with SGC (N = 68) arising from minor salivary glands and SCC (N = 750) in the oral cavity between 1995 and 2017 were reviewed retrospectively. The clinical and pathological factors and treatment outcomes were compared to identify clinical differences between oral SGC and SCC in total cases and in tumor size and subsite (propensity score)-matched pairs (N = 68 in each group). In addition, pattern of local invasion was pathologically assessed in a subset of SGC and SCC tumors.

Results: Patients with SGC in the oral cavity showed >90% survival at 5 years. Most common pathologies of SGC were mucoepidermoid carcinoma (39.7%) and adenoid cystic carcinoma (35.3%), where high-grade tumors (including adenoid cystic carcinomas having solid components, grade 2 or 3) represented only 36.8%. Compared with oral SCC, surgery for SGC had narrow surgical safety margin. However, local control was very successful in SGC even with <5 mm or positive resection margin through surgery plus adjuvant radiation treatments or surgery alone for small low-grade tumors. Pathologic analysis revealed that the frequency of oral SGC with infiltrative tumor border was significantly lower than that of oral SCC (46.4 vs. 87.2%, P < 0.001).

Conclusions: SGC in the oral cavity represents relatively good prognosis and has a locally less aggressive pathology compared with oral SCC. Adjuvant radiation can be very effective to control minimal residual disease in oral SGC. Our study proposed that a different treatment strategy for oral SGC would be reasonable in comparison with oral SCC.

Utility of Fine Needle Aspiration in Diagnosis of Intraoral Minor Salivary Gland Tumors

Objective:

To evaluate the utility of intraoral fine-needle aspiration cytology (FNAC) in diagnosis of minor salivary gland neoplasms (MSGN) with application of Milan system of reporting salivary gland cytopathology; keeping histopathology as gold standard and to detail the cytological findings of MSGNs.

Method:

Retrospective study between Jan 2008 and June 2017 (appro × 10 years) on the cytology of the minor salivary gland tumor along with the histopathological correlation. The relevant clinical data was collected from the medical record.

Result:

Sixty-four cases of MSGNs were included in the study. The histodiagnosis of the 41 were available. Twenty-one cases were diagnosed as malignant, while rest 20 cases were reported as benign. The most common tumor diagnosed was pleomorphic adenoma (PA) (50% cases), followed by mucoepidermoid carcinoma (14%) and adenoid cystic carcinoma (12.5%). The most common site of MSGT was found to be hard palate (44%), followed by soft palate (23%), floor of the mouth (12%), lip (11%), buccal mucosa (5%), and tongue (5%) with no gender predilection. Sensitivity of FNAC for detection of malignancy was 81% while specificity 95%. For malignancies, positive predictive value for malignancies was 17/18 (94.4%) and negative predictive value was 19/23 (82.3%). According to Milan system out of 21 cases in category IV B, 4 cases were found malignant (Category VI), while 1/18 case in category VI turned out to be nonneoplastic lesion (Category II).

Conclusion:

FNAC is imperative in early diagnosis and subsequent management of MSGNs