Odontogenic tumours are lesions that occur solely within the oral cavity and are so named because of their origin from the odontogenic (i.e. tooth-forming) apparatus. Odontogenic tumours comprise a variety of lesions ranging from non-neoplastic tissue proliferations to benign or malignant neoplasms. However, controversies exist regarding the pathogenesis, categorisation and clinical and histological variations of these tumours. The recent 2017 World Health Organization classification of odontogenic tumours included new entities such as primordial odontogenic tumours, sclerosing odontogenic carcinomas and odontogenic carcinosarcomas, while eliminating several previously included entities like keratocystic odontogenic tumours and calcifying cystic odonogenic tumours. The aim of the present review article was to discuss controversies and recent concepts regarding odontogenic tumours so as to increase understanding of these lesions.

Background:Mucins are high-molecular-weight glycoproteins with a high O-linked carbohydrate content, which are synthesized by many secretory epithelial cells as membrane-bound and/or secreted products. Mucin-1 (MUC1) is a transmembrane mucin that protects and lubricates the mucous membranes of the human body and involves itself in various cellular functions such as growth, differentiation and signaling. An aberrant expression of MUC1 has been demonstrated in various human cancers. Many studies on MUC1 expression have been conducted on a variety of neoplastic lesions other than head-and-neck region. In this study, an attempt has been made to evaluate the MUC1 immunoexpression in oral squamous cell carcinoma (OSCC) and normal oral mucosa (NOM).Aims:This study aims to compare and correlate the immunoexpression of MUC1 in NOM and OSCC using immunohistochemical technique.Settings and Design:Thirty patients of OSCC formed the study group and thirty patients were included in the control group (NOM). Formalin-fixed paraffin wax blocks were prepared from the tissue samples obtained.Materials and Methods:Immunohistochemistry (IHC) for MUC1 was performed, and the overall percentage of positive cells along with distribution and localization of immunoexpression was studied.Statistical Analysis:Pearson's Chi-square test was used. P <0.05 was considered to be statistically significant.Results:In OSCC study group, MUC1-positive immunoreaction was observed in 21 (70%) cases out of 30. All the samples in control group were negative for MUC1 immunoexpression. The immunohistochemical expression of MUC1 in OSCC group was statistically significant when compared with normal control group, as P < 0.05 (Pearson's Chi-square).Conclusions:MUC1 is a reliable biomarker for the diagnosis of OSCC, but further studies are required to prove its role in prognosis.

Rhabdomyosarcoma is a malignant neoplasm of mesenchymal cells, showing varying degrees of striated muscle cell differentiation. It predominantly occurs in children while rarely found in adults and involvement of the oral cavity accounts for only 10%–12% of all head-and-neck cases. Herewith, we present a rare case of spindle cell rhabdomyosarcoma in a 52-year old male, involving the mandibular gingiva, and describe the clinical, radiological, histopathological and immunohistochemical findings.

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