What does it mean to have cobblestoning of the posterior pharyngeal wall?

The term cobblestoning is used to describe streaks of lymphoid tissue (the cells that fight bacteria) on the posterior pharynx (throat) which is usually seen with allergic rhinitis (chronic runny nose). My doctor told me that the appearance is that of a cobblestone street, hence the name. It in itself is not dangerous or life threatening but the cause of this condition could be serious and should be treated. This is also seen a lot with chronic postnasal drip.