Renal lymphoma is usually a part component of multi-systemic lymphoma - primary renal lymphoma is unusual.
Typical imaging findings are multiple bilateral hypodense or infiltrative renal masses.
While renal lymphoma has an autopsy incidence of ~45% (range 30-60%) in lymphoma patients, the incidence by CT evaluation is ~5% 1.
The kidneys are the most common abdominal organ affected by lymphoma. Most instances are B-cell non-Hodgkin lymphoma; primary renal lymphoma is rare (<1%).
Involvement of kidneys in Hodgkin lymphoma is rare (<1%).
Patients present with flank pain, weight loss, hematuria, or a palpable mass. Acute renal failure may be seen in infiltrative disease.
Renal lymphoma occurs commonly with non-Hodgkin lymphoma. The majority have intermediate or high-grade lymphomas including Burkitt and histiocytic varieties 2. Most are B-cell lymphoma.
On gross examination, lesions are fleshy or firm yellow, tan, or grey tumors of 1-20 cm size.
It is the most sensitive imaging for the involvement of the renal collecting system and ureters, as well as provides functional information.
Hypoechoic lesions (single/multiple) within renal parenchyma with very little internal vascularity.
The following patterns of disease may be seen on CT:
- multiple masses (up to 60%: most common pattern)
- typically 1-3 cm in size
- associated with enlarged retroperitoneal nodes (≥50%)
- single mass (over 20% of cases)
- up to 15 cm
- homogeneous, hypodense without cystic change
- calcium, bleed, or necrosis
- invasion from retroperitoneal nodal mass (over 30% of cases)
- usually >10 cm
- encasement of vessels without thrombosis, +/- hydronephrosis
- diffuse infiltration (up to 20% of cases)
- no discrete mass
- usually bilateral
- seen with Burkitt lymphoma
- perirenal mass (less than 10% of cases)
- perirenal stranding
- thickening of Gerota fascia
- perirenal nodules
- atypical patterns:
- spontaneous hemorrhage
- heterogenous lesion
- cystic changes
Features include 3:
- T1: hypointense to renal parenchyma
- T2: iso or hyperintense to renal parenchyma
- poor enhancement compared to renal parenchyma
- delayed enhancement is seen in some lesions
Imaging differential considerations include:
- 1. Urban BA, Fishman EK. Renal lymphoma: CT patterns with emphasis on helical CT. Radiographics. 20 (1): 197-212. Radiographics (full text) - Pubmed citation
- 2. Hartman DS, David CJ, Goldman SM et-al. Renal lymphoma: radiologic-pathologic correlation of 21 cases. Radiology. 1982;144 (4): 759-66. Radiology (abstract) - Pubmed citation
- 3. Sheth S, Ali S, Fishman E. Imaging of renal lymphoma: patterns of disease with pathologic correlation. Radiographics. 2006;26 (4): 1151-68. doi:10.1148/rg.264055125 - Pubmed citation
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