The PLQIMP integrated multi-port architectural ceiling diffuser provides the building designer with the desired appearance and superior performance of a uniform radial discharge air pattern. A 360° horizontal pattern delivers even air throughout the space. The PLQIMP is designed with an integral multi-port diffusion ring to increase localized room air mixing and induction. The diffuser has a square faceplate made of one-piece, nonfolded material with rounded corners resulting in a clean appearance that is unobtrusive to ceiling systems. The single faceplate gives the diffuser reduced pressure drops and a quiet sound profile and is held in place by hooks that lock into the backpan. The one-piece, stamped backpan provides smooth, consistent corners, exacting dimensions, and performance tolerances. The removable faceplate offers easy duct and damper access.