Papillary Cystadenoma Lymphomatosum (Warthin's tumour). - This represents about 5-15% of parotid tumours and almost always occurs in the lower portion of the parotid overlying the angle of the mandible. Infrequently these tumours occur bilaterally or in other salivary glands. It is the only salivary neoplasm that occurs preponderantly in males above 40 years. This tumour presents as a slow growing painless swelling over the angle of the jaw. The overlying skin looks normal. The surface of the swelling is smooth and well defined and the margin is distinct. Consistency is soft, often fluctuate, but not translucent. The regional Hymph nodes are not enlarged. This tumour was previously considered to be teratoid or branchiogenic in origin. But today it is believed that the tumour is essentially epithelial in origin and that the lymphoid component represents reactive element perhaps of immunologic origin, comparable to that seen in Hashimoto's thyroditis or Sjogren's syndrome. This tumour is composed of cystic or glandular spaces lined by columnar epithelium within an abundant lymphoid tissue, harbouring germinal centres. The cells are eosinophilic. Though this tumour may be firm, yet it may be soft and frequently cystic. Irregular papillary processes of tall columnar epithelium project into the cystic spaces. This tumour is more often seen in white races and not seen in Negroes. These are encapsulated lesions and do not undergo malignant tranformation. However they are susceptible to infection and may sometimes be converted into abscess. Carcinoma of the parotid gland (adenocarcinoma, epidermoid and undifferentiated carcinoma). - The patients are usually over 50 years of age. Males and females are equally affected. The main camplaint is a rapidly enlarging swelling in the parotid region which was painless to start with, but become painful at later stage particularly during movements of the jaw. The pain may radiate to the ear and over the side of the face. On examination there is often infiltration of the tumour to the overlying skin, when the skin becomes tethered and reddish blue. It also becomes hyperaemic. But the tumour is not tender (cf. acute parotitis when the swelling is extremely tender).