Most common cause of unilateral parotid swelling in a 27 yr old male is:
They are the commonest tumors of the parotid gland & account for 60% of tumors in the Parotid. Ref: Robbin's Basic Pathology, 5th Edition, Page 750; Bailey and Love's Sho Practice of Surgery, 22nd Edition, Page 475 and 23rd Edition, Page 659; CSDT, 11th Edition, Page 294.
Wahins tumor
Pleomorphic adenoma
Adenocarcinoma
Haemangioma