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date, most of the epidemiological studies on salivary gland tumours are limited for a variety of reason including being out of date, extrapolated from either a single centre or country studies, or investigating either major or minor glands only.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.

The range of lesions seen in Saudi geriatric patients were similar to those reported for other parts of the world, although the lesions were more similar to those reported from developing countries. The very high rate of oral cancer, however, is expected to take the majority of the resources allocated to geriatric oral health care, except if a strong, population-based prevention program is initiated immediately.

Most MEC of minor salivary glands appear to be low-grade tumors. It is conceivable that some grading methods (Brandwein and modified Healy) may lead to an unnecessary escalation of management methods in these tumors. The MSKCC method may have emphasized some parameters which may not have much importance in minor salivary gland MEC. The AFIP method appears to be the most appropriate to use for the grading of minor salivary gland MEC. Further studies are required to confirm or disprove this finding.

Primary intraosseous squamous cell carcinoma (PIOSCC) is a rare malignant neoplasm that has an exquisitely exclusive affection to the jawbone. It is defined as squamous cell carcinoma arising within the jaw and developing from residual odontogenic epithelium or from a preexisting odontogenic cyst or tumor. The solid-type of this tumor is a central jaw carcinoma arising de novo and has no initial connection with the oral mucosa. Herein, we report a case of solid-type PIOSCC involving the mandible in a 37-year-old male patient elucidating its histopathological and imaging findings. The patient underwent surgical resection followed by post-operative adjuvant radiotherapy. The close 2-year follow up of the patient revealed neither locoregional nor distant metastasis.

Peripheral dentinogenic ghost cell tumor is a rare tumor with only 24 cases previously described in the English literature. The majority of cases have been reported to occur in the anterior part of the jaws. A case occurring in posterior (molar region) of the mandible in a 75-year-old edentulous woman is reported. The patient presented with a nodular swelling in the left mandible that showed erosion (saucerization) of the underlying bone radiographically. On microscopy, the tumor showed mainly solid epithelial islands resembling ameloblastoma in fibrous connective tissue. The islands were associated with ghost cells and dysplastic dentin. This report includes the clinical, radiographic, and microscopic features of the patient, in addition to the review of the English literature on the tumor.

Oral leiomyomatous hamartoma (OLH) is a rare lesion seen in the oral cavity. It mainly presents on the median maxilla and tongue. In the literature in English, there are only 10 reported cases of OLH of the median maxilla. Most of the cases were found in patients of Japanese and Latin American origin. We report a case of OLH in an 18-month-old boy of Middle Eastern ancestry. The lesion presented as a pedunculated, light pink, soft swelling that was located on the labial gingiva of tooth number 21. Microscopically, it showed proliferative smooth-muscle fascicles dispersed in loose fibrous stroma and multiple small vessels. The lesional cells looked mature and elongated and were deeply eosinophilic spindle cells with basophilic, central "cigar-shaped" nuclei. The diagnosis of OLH was supported by positive immunohistochemical reactivity of smooth-muscle actin and desmin. To our knowledge, this is the first reported case of OLH in a Middle Eastern patient.

A cystic swelling in the parotid gland should lead to a differential diagnosis that includes benign cystic lesion of the gland, benign tumors that are frequently associated with cystic degeneration or entirely cystic de novo, or even a malignant neoplasm. The case presented is that of a cystic parotid swelling of 2 years' duration in a 52-year-old female patient. The clinical differentials in the present case were reviewed and were entirely different from the final histological diagnosis of low-grade mucoepidermoid carcinoma. The uniqueness of this case is the very rare unicystic presentation of the lesion. The authors also discuss why the clinical and radiological investigations were not suggestive of the final diagnosis.

A role for incisional biopsy in preoperative prognostication is increasingly being advocated in oral tongue squamous cell carcinomas (OTSCC). Biopsies at two locations were compared, and prognostic factors in biopsies and their corresponding resections were evaluated. A total of 138 OTSCC biopsy slides from Finland and Saudi Arabia were compared for size (horizontal and vertical) and invasive front. The Finnish cases were assessed for tumor stroma ratio (TSR) and tumor‐infiltrating lymphocytes (TILs) using light microscopy and digital image analysis assessment and compared. Furthermore, TSR, TILs, and previously analyzed budding and depth of invasion (BD) score in biopsies were compared with their evaluation in the corresponding resections. Fifty‐nine percent of Finnish and 42% of Saudi Arabian biopsies were ≥ 5 mm deep, while 98% of Saudi Arabian and 76% of Finnish biopsies were ≥ 5 mm wide. Assessment of invasion front was possible in 72% of Finnish in comparison with 40% of Saudi Arabian biopsies. There was 86.8% agreement between TSR and 75% agreement between TIL evaluation using light microscopy and digital assessment. Significant agreement was obtained on comparing the TSR (p = 0.04) and BD (p < 0.001) values in biopsies and resections. Biopsies of ≥ 5 mm depth from representative OTSCC areas are essential for prognostic information. Clinical pathologists are advised to assess BD score and TSR for prognostic features in such biopsies.