<prompt> Which of the following head and neck tumor has the worst prognosis? -Adenoid cystic carcinomaAcinic cell carcinomaCystadenolymphomaMucoepidermoid carcinoma  <response>: Adenoid Cystic Carcinoma CylindromaThis is a highly malignant tumor due to its typical infiltrativenature, especially along the nerve sheaths. Adenoidcystic carcinoma is histologically characterized by cribriformappearance i.e. the epithelial tumor cells of duct-lining andmyoepithelial cells are arranged in duct-like structures ormasses of cells, having typical fenestrations or cyst-likespaces and hence the name adenoid cystic. HARSH MOHAN Textbook of pathology 6th edition pg no 537 