<prompt> Unilateral middle ear serous effusion in an adult, most common cause ?TBForeign bodyNasopharyngeal carcinomaCSOM  <response>: Ans. is c i.e., Nasopharyngeal carcinoma In adults presenting with a unilateral middle ear effusion the possibility of a nasopharyngeal carcinoma should be considered-- Current otolaryngology 2de p. 659 A 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 regions. - Scott Brown 7de Vol III p. 3389 