<prompt> Which of the following head and neck tumor has worst prognosis?Adenoid cystic carcinomaAcinic cell carcinomaCystadenolymphomaMucoepidermoid carcinoma  <response>: Ans. is a i.e., Adenoid cystic carcinoma Adenoid cystic carcinoma has been described as one of the most biologically aggressive and destructive malignant neoplasms, presenting a tendency for local recurrance and late distant metastasis throughout the course of disease. o The adenoid cystic carcinoma, adenocarcinoma, squamous cell carcinoma and undifferentiated carcinoma are all agggressive malignant tumors that carry a poor prognosis regardless of treatment. o The acinic cell carcinoma and the mucoepidermoid carcinoma, although undoubtedly malignant tumors with a potential for local invasion and metastatic spread, are frequently very low grade histologically and do not require the radical treatment needed for more aggressive tumors. o Cysadenolymphoma Wahins tumor is a benign tumor. 