What are the CT and MRI features of renal lymphoma?
Renal lymphoma is uncommon, given the lack of lymphoid tissue in the kidneys, and is most often secondary to non-Hodgkin’s lymphoma (occurring in 6% of patients at presentation). Treatment is with systemic therapy rather than with surgical resection.
On CT and MRI, multiple renal masses are most commonly seen (in 50% to 60%), followed by direct contiguous spread from adjacent lymphadenopathy into the kidney (in 25% to 30%), diffuse renal infiltration (in 20%) which almost always occurs bilaterally, and a solitary renal mass (in <10%). Associated soft tissue extension into the perinephric tissues is sometimes also present. Lymphoma generally has soft tissue attenuation on CT, appears hypointense on T1-weighted images and isointense-slightly hyperintense on T2-weighted images relative to renal parenchyma, and restricts diffusion. Lymphomatous lesions are typically homogeneous, are hypoenhancing, and exert little mass effect upon subjacent structures. There is usually no venous extension or ureteral obstruction, but presence of abdominal lymphadenopathy is common