Diagnostic difficulties in lesions of the minor salivary glands

Polymorphous Adenocarcinoma: A Systematic Review of the Literature and Presentation of Two Cases in a Less-Considered Anatomical Site

BACKGROUND

Polymorphous adenocarcinoma (PAC) is the second-most common malignant tumour of the minor salivary glands. Although PAC predominantly affects the palate, it can also involve the buccal mucosa. This systematic review aims to investigate the literature data about PAC. Furthermore, we report two cases of patients affected by PAC in an infrequently considered anatomical site.

METHODS

According to PRISMA guidelines, a systematic review search was conducted on PubMed, Scopus, and Web of Science. Observational studies conducted on patients with a histological diagnosis of PAC were selected and analysed. Furthermore, two cases of patients with PAC affecting the buccal mucosa were reported.

RESULTS

Twenty-nine studies were included, and 143 patients affected by PAC were analysed (62 males, 75 females, and 6 undefined, with a mean age of 57.4 ± 14.5 years). The palate was the most affected site (99/143, 69.2%), followed by the buccal mucosa (12/143, 8.4%). Moreover, we report two cases of patients with PAC affecting the buccal mucosa (one male and one female, with a mean age of 70.5 ± 2.5 years).

CONCLUSIONS

The present study underscores the importance of considering the buccal mucosa as a possible location of minor salivary gland tumours; although it is a less-considered affliction, it is not uncommon.

A 10-Year Review of Intraoral Salivary Gland Tumor Diagnoses: Diagnostic Challenges and Inter-Observer Agreement

BACKGROUND

Salivary gland tumors (SGT) are a diverse group of neoplasms arising from the major and minor glands. The oral cavity is the most common site for minor SGT (IMSGT), and these lesions frequently pose a challenge to the pathologist due to overlapping histopathological features and limited material for analysis. Our objective was to determine specific clinical and histopathological features associated with challenges in IMSGT diagnoses and pathologists' agreement.

METHODS

We conducted a retrospective analysis of 248 IMSGT received between 2010 and 2019. We evaluated the diagnostic challenge of the cases by stratifying according to whether a definitive, favored, or indeterminate (challenging) diagnosis was provided. Inter-observer agreement and concordance of biopsy diagnoses with the final diagnoses after tumor resection were evaluated.

RESULTS

Of the 248 biopsies, 191 had a definitive diagnosis, 38 favored diagnoses, and 19 were indeterminate. The predominant diagnoses considered for the indeterminate category were pleomorphic adenoma/myoepithelioma (PA), polymorphous adenocarcinoma (PAC), adenoid cystic carcinoma (AdCC), and low-grade adenocarcinoma. Using multivariate analysis of clinical features, younger patient age, smaller tumor size, and larger biopsy size increased the likelihood of a definitive diagnosis (p = 0.014, p = 0.037, p = 0.012). The inter-observer agreement for 68 representative cases was moderate overall (Fleiss's Kappa 0.575) and good for the 40 cases with a definitive diagnosis (Fleiss's Kappa 0.66). Sixty-five biopsy diagnoses were matched with corresponding tumor resection diagnoses and found to show a good concordance (Cramer's V test 0.76). The discordant diagnoses predominantly involved PA, carcinoma exPA, PAC, AdCC, and adenocarcinoma NOS.

CONCLUSION

Diagnostic challenges in IMSGT incisional biopsies were infrequent, especially if multiple pathologists were consulted. PA, PAC, AdCC, and adenocarcinoma NOS were the histologic types more commonly posing diagnostic challenges. Younger patient age, smaller tumor size, and larger biopsy are associated with a definitive diagnosis. This data highlights the importance of appropriate sampling in IMSGT.

Distribution and Frequency of Salivary Gland Tumours: An International Multicenter Study

BACKGROUND

Salivary gland tumours (SGT) are a relatively rare group of neoplasms with a wide range of histopathological appearance and clinical features. To date, most of the epidemiological studies on salivary gland tumours are limited for a variety of reason including being out of date, extrapolated from either a single centre or country studies, or investigating either major or minor glands only.

METHODS

This study aimed to mitigate these shortcomings by analysing epidemiological data including demographic, anatomical location and histological diagnoses of SGT from multiple centres across the world. The analysed data included age, gender, location and histological diagnosis from fifteen centres covering the majority of the world health organisation (WHO) geographical regions between 2006 and 2019.

RESULTS

A total of 5739 cases were analysed including 65% benign and 35% malignant tumours. A slight female predilection (54%) and peak incidence between the fourth and seventh decade for both benign and malignant tumours was observed. The majority (68%) of the SGT presented in major and 32% in the minor glands. The parotid gland was the most common location (70%) for benign and minor glands (47%) for malignant tumours. Pleomorphic adenoma (70%), and Warthin's tumour (17%), were the most common benign tumours whereas mucoepidermoid carcinoma (26%) and adenoid cystic carcinoma (17%) were the most frequent malignant tumours.

CONCLUSIONS

This multicentre investigation presents the largest cohort study to date analysing salivary gland tumour data from tertiary centres scattered across the globe. These findings should serve as a baseline for future studies evaluating the epidemiological landscape of these tumours.

Sclerosing polycystic adenosis of the oral cavity

Minor salivary glands are ubiquitous in the oral cavity, and related diseases are often indolent and asymptomatic. We describe the unusual features of sclerosing polycystic adenosis, and its similarities to more sinister conditions of the minor salivary glands. Its importance is currently uncertain and research points to a pathogenesis that is neoplastic, which can create ambiguity. Sclerosing polycystic adenosis is a newly-discovered condition that merits further discussion and research to evaluate its full impact.