Involvement of bladder by lymphoma is more often a reflection of systemic disease (up to 20% of cases).
Primary lymphoma of the bladder is exceedingly rare (<1% of cases).
Gross: lumps and bumps beneath a normal-appearing mucosa.
Dense lymphoid infiltrates diffusely through the bladder wall (image A).
Most secondary lymphomas are diffuse large B-cell lymphomas (high-grade, image B); others include low-grade lymphomas (follicular lymphoma, small lymphocytic lymphoma, marginal zone and mantle cell lymphoma).
Most common primary bladder lymphoma is mucosa-associated lymphoid tissue (MALT) lymphoma (a low grade B-cell lymphoma).
Primary MALT lymphoma has excellent prognosis; secondary lymphomas have poorer prognosis, but also depends on the lymphoma grade.