<prompt> Unilateral middle ear serous effusion in an adult, most common cause isTBForeign bodyNasopharyngeal carcinomaCSOM  <response>: In adults presenting with a unilateral middle ear effusion, the possibility of a nasopharyngeal carcinoma should be consideredA high incidence of NPC Nasopharyngeal carcinoma in South East Asia and southern China correlates with the high incidence of OME Otitis Media with Effusion in adults in these regionsRef: PL Dhingra, Diseases of Ear, Nose Throat, 7th edition, pg no. 279 - 286 