A 45-year-old female patient complains of a slightly painful, tumourlike formation in the right parotid region that appeared two months ago for no apparent reason. The patient notes weakness, occasional body temperature rise up to 37, 2°C - 37,6°C. Two weeks ago she underwent the anti-inflammatory therapy which did not have positive effect. Objectively: the face is asymmetric due to a minor swelling in the right parotid region. Palpation reveals a roundish dense and elastic formation with even contours, it is slightly painful, not adherent to the skin. Incisive canal exudes a small amount of transparent saliva. What is the most likely diagnosis?