Teenager with nasal stuffiness

CT of antochoanal polyp
Axial CT with contrast of the face (left) shows a low-density left-sided polyp originating in and filling the left maxillary sinus which extends medially to the nasal cavity and which on the sagittal CT (right) is then seen to continue to extend inferiorly into the posterior nasopharynx and oropharynx.

The diagnosis was antrochoanal polyp.