AbstractDissimilarities in the spatial distribution of small (μm–size) and large (mm–size) dust grains at the cavity edge of transition disks have been recently pointed out and are now under debate. We obtained VLT/NACO near-IR polarimetric observations of SAO 206462 (HD 135344B). The disk around the star shows very complex structures, such as dips and spirals. We also find an inner cavity much smaller than what is inferred from sub-mm images. The interaction between disk and orbiting companion(s) may explain this discrepancy.