Renal lymphoma: demonstration by MR imaging.

OBJECTIVE

The objective of this study was to demonstrate the spectrum of appearances of renal lymphoma using current MR techniques including gadolinium enhancement.

MATERIALS AND METHODS

Twelve patients with renal lymphoma were examined by MR imaging on a 1.5-T scanner. MR examinations included T2-weighted, breath-hold T1-weighted spoiled gradient-echo, and T1-weighted fat-suppressed spin-echo imaging before and after gadolinium administration. Tumor morphology, signal intensity, and enhancement features were evaluated.

RESULTS

Three types of renal involvement were observed: large paraaortic retroperitoneal masses with extension into the renal hilum, the subcapsular space, or both (nine patients); unilateral diffuse infiltration of the renal parenchyma (one patient); and focal rounded intraparenchymal masses (two patients). Untreated lymphoma (10 patients) was slightly hypointense relative to the renal cortex on T1-weighted images and was heterogenous and slightly hypointense or isointense on T2-weighted images. Enhancement of lymphomatous tissue was mildly heterogenous and was minimal on early images after gadolinium enhancement and remained minimal on late contrast-enhanced images in most tumor masses. No central necrosis of tumor was identified, and no renal vein thrombus was present. Five patients with lymphoma that presented as a large paraaortic mass showed diminished renal cortical perfusion of the involved kidney. All of these patients also had tumor extension into the renal hilum.

CONCLUSION

Three types of renal involvement with lymphoma were observed. The most common appearance was a large retroperitoneal mass that invaded the kidney. Tumors had low to intermediate signal intensity on T1- and T2-weighted images and had diffuse heterogenous enhancement that was less than that of renal parenchyma.