Mantle cell lymphoma involving the kidney in a 55 y/o male. The nephrectomy specimen showed multiple small greyish-white nodules with granular consistency. They ranged in size from microscopic to 1.0 cm. The tumor cells were positive for CD20, CD43, PAX-5, IgD, Cyclin D1, bcl-2 and lambda light chains. They were negative for CD10, bcl-6, CD5, and kappa light chains.