Introduction. Pleomorphic adenoma is known as the most common tumour in salivary glands that makes up 60-90% of all benign tumours of the salivary glands. The modern genetic tendency towards the diagnosis of salivary gland tumours is the study of the role of microRNA molecules, and miRNA-29a in the focus of the great researchers’ interest. It is expressed in 84 % of the pleomorphic adenomas of the salivary glands. Objectives. Determination of expression of miRNA-29a in tissues of pleomorphic adenomas of the large salivary glands that adjacent to the tumour of the tissue of the salivary gland, intact tissue of the salivary gland, was out of touch with the tumour and venous blood. Materials and methods. The study included 20 patients with benign tumours of the large salivary glands (pleomorphic adenomas). The expression of miRNA-29a was evaluated by using reverse transcription and quantitative polymerase chain reaction (qPCR) in real time.
Results. The analysis of the level of miRNA-29a expression revealed that among 4 groups of indicators (tumour tissue, tissues adjacent to the tumour salivary gland tissue, intact salivary gland, which was out of touch with the tumour and venous blood) in patients with pleomorphic adenoma of the large salivary gland, the highest expression was noted in the group, where salivary gland tissue was adjacent to the salivary gland tumour (111, 93±56, 97 versus 8,12±4,4). Correlation analysis of patients with pleomorphic adenoma of the large salivary glands with different fragments of tissues samples demonstrated that the expression level of miRNA-29a differed significantly between the groups (adjacent gland - intact salivary tissue).
Conclusions. A sufficiently high level of miRNA-29a expression in the tissues of pleomorphic adenoma in the large salivary glands compared with the normal (intact salivary gland tissue), 10 times as much can be used as a genetic marker for verification (identification) of this type of tumours. Studies of biopsy material from patients with pleomorphic adenoma in the large salivary glands at the genetic level (by expression of miRNAs-29a) confirm the need not only in enucleating of the tumour (partial parotidectomy), but also in performing of subtotal resection with removal of salivary gland adjacent to the tumour.
Pleomorphic adenoma originating from submandibular heterotopic salivary gland tissue: A case report and review of the literature