Figure 6a. Squamous cell carcinoma of the left piriform sinus. (a) Axial CT scan obtained during quiet respiration shows that the mucosal surfaces of the left piriform sinus are apposed (arrows); therefore, no evident lesion is observed. The postarytenoid soft tissue and the posterior pharyngeal wall are apposed. (b) Axial CT scan obtained during the Valsalva maneuver shows tumoral thickening of the lateral wall of the left piriform sinus (arrows). The postarytenoid soft tissue and the posterior pharyngeal wall are separated and clearly depicted. Arrowhead = level III adenopathy.