Which findings on CT scans are characteristic of renal lymphoma?

Updated: Mar 22, 2019
  • Author: Ali Shirkhoda, MD; Chief Editor: Eugene C Lin, MD  more...
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Answer

Typical imaging findings of renal lymphoma include multiple poorly enhancing masses, retroperitoneal tumors that directly invade the kidneys, a solitary mass, bilateral renal enlargement, and perirenal soft-tissue masses. Unless the renal lesions manifest in the setting of widespread lymphoma, percutaneous biopsy is indicated to differentiate lymphoma from metastases. Radiologists should be familiar with both the typical and atypical manifestations of renal lymphoma and should recommend imaging-guided percutaneous biopsy for diagnostic confirmation to avoid unnecessary nephrectomy. [2]

Multiple renal masses are most common in patients with lymphoma. The masses are typically bilateral, but they may also be unilateral. Multiple masses are seen in approximately 60% of patients, and they reflect advanced disease in patients who present for staging evaluation. Depending on the size and expansile nature of individual neoplastic deposits, little mass effect on the renal contour may be seen. Therefore, although renal involvement may be extensive, imaging findings can be subtle, and intravenous contrast enhancement is essential.

The masses range in size from a few millimeters to several centimeters and are seen as areas of low attenuation. Although the masses are often homogeneous on CT scans, they can be heterogeneous or low density, as well as mimic a complicated cyst. This is typically a sign of tumor necrosis inpatientsundergoingchemotherapy.In approximately 50% of patients, associated retroperitonealadenopathyis noted. (See the images below.)

Computed tomography scan in a 36-year-old woman. T Computed tomography scan in a 36-year-old woman. This image reveals multiple lymphomatous masses that involve the right kidney, in which the largest mass shows areas of necrosis. A few lymph nodes are evident in the right-sided renal pedicle. Note that the patient has splenomegaly, with probable involvement of the liver and associated ascites and a vertebral bony lesion.

Solitary masses are reported in approximately 10-20% of patients (see the images below). The mass can be as large as 15 cm and can cause significant distortion of the renal contour. Solitary lesions resemble other renal neoplasms that grow primarily by expansion, including renal cell carcinoma or isolated metastasis.

Computed tomography scan in a 53-year-old woman wi Computed tomography scan in a 53-year-old woman with lymphoma. A large relatively homogeneous mass involving the left kidney is associated with ipsilateral adenopathy. Note the beginning of minimal necrotic changes in the renal mass and the para-aortic nodes (cursors). A lymphomatous mass is seen in the liver. The pattern can be easily mistaken for renal cell carcinoma and associated with retroperitoneal adenopathy and hepatic metastasis. Note the thick-walled loop of small bowel from lymphoma anterior to the nodal mass.
Contrast-enhanced computed tomography (CT) scan in Contrast-enhanced computed tomography (CT) scan in a 28-year-old woman with non-Hodgkin lymphoma, who presented with left flank pain. A renal sonogram (not shown) depicted left hydronephrosis and renal mass. This CT scan shows retroperitoneal extension of lymphoma to the left kidney, in which a large mass in the left side of the retroperitoneum extends into the left kidney. Adenopathy in the left hilar region appears to displace the renal vein and surround the renal artery without obstructing the blood flow. The posterior collecting system is dilated as a result of obstruction of the ureter by adenopathy that is present more caudally in the retroperitoneum (not shown).

Continuous retroperitoneal extension into the kidney is a common pattern of renal involvement in lymphoma and is seen in approximately 30% of patients (see the image below). Continuous extension typically results in a large, bulky retroperitoneal mass that envelops the renal vasculature and invades the renal hilus. In most patients, the renal vascular pedicle is patent and engulfed by the retroperitoneal mass. Continuous extension of retroperitoneal involvement in the renal collecting system can often cause obstruction, and patients commonly present with hydronephrosis.

Contrast-enhanced computed tomography scan in a 28 Contrast-enhanced computed tomography scan in a 28-year-old woman with non-Hodgkin lymphoma (same patient as in the previous image) that was obtained to evaluate response to chemotherapy approximately 5 months after the patient underwent treatment. This image shows a mild degree of atrophy in the left kidney but complete resolution of the adenopathy and mass. The atrophy may also have been the result of long-standing hydronephrosis.

Rarely, perirenal disease is seen in an isolated form without involvement of the renal parenchyma or retroperitoneal nodes (see the images below). Occasionally, this feature is seen without compression of the renal parenchyma or functional impairment; such a finding is rare and virtually pathognomonic for perirenal lymphoma. A variety of CT scan manifestations of perirenal lymphoma, including renal sinus infiltration, thickening of the Gerota fascia, and perirenal masses, have been described. The normal renal parenchyma cannot be differentiated from the perirenal abnormality if intravenous contrast enhancement is not used in CT scanning.

Nonenhanced computed tomography scan obtained in a Nonenhanced computed tomography scan obtained in a 62-year-old man with a palpable flank mass and elevated levels of serum blood urea nitrogen and creatinine. This image shows large bilateral masses that cannot be distinguished from the renal parenchyma. A few calcifications are seen on the left side. No retroperitoneal adenopathy is noted.
Computed tomography scan in a 72-year-old woman wi Computed tomography scan in a 72-year-old woman with a known diagnosis of non-Hodgkin lymphoma. This image shows perirenal lymphoma with retroperitoneal adenopathy. Massive retroperitoneal adenopathy, splenomegaly, and a bilateral rim of low-attenuating tissue that surrounds the kidneys are noted. These findings are typical of perirenal lymphoma. The spleen has a large area of low attenuation as a result of tumor infiltration. Adenopathy, splenomegaly, and the perirenal process completely resolved after chemotherapy.

Infiltrative disease is associated with lymphomatous proliferation within the interstitium of the kidney, which manifests as nephromegaly, with preservation of renal contour (see the image below). Diffuse infiltration is often bilateral and is seen in approximately 20% of patients. The diagnosis is often subtle and depends on the finding of global renal enlargement. Usually, kidneys infiltrated by lymphoma have poor function, but the disease is often clinically silent.

Nonenhanced computed tomography scan in a 22-year- Nonenhanced computed tomography scan in a 22-year-old woman with non-Hodgkin lymphoma and elevated levels of blood urea nitrogen and creatinine. An infiltrative pattern of renal lymphoma is seen as lymphomatous infiltration within the interstitium of the kidneys, which causes bilateral nephromegaly. Note the areas of slightly lower attenuation and the preservation of the renal contour.

Atypical manifestations of renal lymphomatous mass, such as spontaneous hemorrhage, necrosis, heterogeneous attenuation, cystic transformation, and calcifications, are occasionally depicted on CT scans. Often, these findings are the result of previous treatment for renal lymphoma. More commonly, the findings of renal lymphoma regress after chemotherapy, and the kidneys regain a normal CT scan appearance.

In patients who are immunocompromised, the prevalence of lymphoma is increased. Lymphoma typically occurs in patients with human immunodeficiency virus infection or in secondarily immunosuppressed recipients of organ transplants. Lymphoma is particularly common in patients who have undergone cyclosporine therapy.

Typically, lymphoma in patients who are immunocompromised is of small, noncleaved cell or immunoblastic origin and has a B-cell phenotype. This condition often has an extranodal origin, and the most common sites include the central nervous system, bone marrow, gastrointestinal tract, lungs, heart, and liver. Renal involvement also occurs in these patients, but it is uncommon.


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