4.8 Renal Lymphoma

•Microor macro-aneurysms

•Sharply marginated

•Dense early arterial network

•Late whorled appearance

•Absent AV shunting

4.7.6Treatment and Prognosis

•Small angiomyolipomas found incidentally usually require no therapy.

•These should be followed-up to assess for growth.

their slow growth.

to preserve as much kidney tissue as possible when removing any lesion.

•Large angiomyolipomas are treated by embolization which reduces the risk of hemorrhage and can also shrink the lesion.

•A side effect of this treatment is postembolisation syndrome.

•Post-embolization syndrome usually lasts for few days and includes:

–Severe abdominal pain

–Fever

–Nausea and vomiting

4.8Renal Lymphoma

by:

–Embolization

–Partial nephrectomy

•Angiomyolipomas that present with retroperitoneal hemorrhage are treated with emergency embolization and nephrectomy should be avoided unless no interventional radiological facility is available.

•Angiomyolipomas smaller than 4 cm in diameter are typically asymptomatic; those larger than 4 cm in diameter are more likely to spontaneously hemorrhage, leading to flank or abdominal pain, hematuria, or even severe life-threatening hemorrhage.

•Severe retroperitoneal hemorrhage has been termed Wunderlich syndrome.

•Rarely, angiomyolipoma may become locally aggressive and invade neighboring structures. Extension into the inferior vena cava and regional lymph nodes has been described.

•The recent literature advocates US evaluation

of patients with tuberous sclerosis every 2–3 years before puberty and yearly thereafter to identify growing lesions.

•Angiomyolipomas larger than 4 cm in diameter should be treated with partial nephrectomy or selective catheter embolization to prevent potentially life-threatening hemorrhage.

•In tuberous sclerosis, typically many angiomyolipomas affect each kidney and it is vital

•Primary Renal lymphomas (PRL) are defined as lymphomas arising in the renal parenchyma and not invasion from an adjacent lymphomatous mass or as a part of disseminated disease.

•In 1980, Coggins reported the first patient diagnosed with a PRL.

•Primary renal lymphoma is very rare.

•PRL accounts for 0.7 % of all extranodal lymphomas and represents less than 1 % of all renal tumors.

•Lymphomatous involvement of the kidney is often seen as a part of disseminated disease.

•PRL is a rare disease in which the etiology and pathogenesis are unclear.

•The kidneys are involved in 12 % of children with non-Hodgkin’s lymphoma.

4.8.2Etiology and Pathogenesis

•Primary lymphoma of the kidney is extremely rare since the kidney has no lymphatic system.

•Renal involvement is mainly due to hematogenous or direct spread of lymphoma from adjacent lymph nodes.

•The proposed pathogenetic mechanismsof renal lymphomas include:

–Origin in the subcapsular lymphatics

–Seeding via hematogenous route

–Extension from retro peritoneal disease or inflammatory disease with a lymphoplasmacytic infiltrate

4.8.3Diagnosis

•Lymphoma commonly involves the kidney secondarily from direct retroperitoneal extension or hematogenous metastases.

•As many as 62 % of patients with lymphoma have renal involvement at autopsy, although only 3 %–8 % of these patients demonstrate renal involvement on abdominal CT-scan (Figs. 4.88, 4.89, and 4.90).

•Primary renal lymphoma is very rare.

•Malbrain proposed several criteria to diagnose primary renal lymphoma as follows:

–Acute renal failure at the presentation in the absence of other causes of renal impairment.

–Rapid improvement of renal function after treatment

–Increased kidney size without any urinary tract obstruction

–Absence of other nodal involvement beyond the kidney

–A confirmed diagnosis made by biopsy

•The most commonly encountered radiological feature is that of multiple soft tissue masses, ranging from 1 to 3 cm, with minimal enhancement after contrast compared to surrounding renal parenchyma.

•The presence of solitary renal lesion makes it difficult to diagnosis as it resembles the more common renal cell carcinoma (RCC).

•The differentiating features of renal lymphomas include:

–Absence of calcification

–Post contrast homogenous attenuation

–Absence of renal vein thrombus

–Absence of a mass effect on renal vessels and pelvicalyceal system in PRL.

–However, this situation still demands a biopsy to rule out RCC.

•Other less commonly seen patterns in those with renal lymphomas include:

–Enlarged non enhancing kidneys

–Direct invasion of renal sinus and hilum by bulky retroperitoneal mass

–A diffuse perirenal infiltration encasing the kidney

–Most of the patients also have adjacent retroperitoneal adenopathy.

•MRI is currently becoming the imaging modality of choice for evaluation of renal lesions.

–Lower signal intensity on unenhanced T1-weighted images than normal renal cortex and less enhancement on early gadolinium-enhanced images differentiates renal lymphoma from renal cell carcinoma.

•It is essential to differentiate between renal cell carcinoma and renal lymphoma in patients presenting with solitary renal masses.

•Preoperative biopsy is worthwhile in patients with atypical radiological features, since it may avoid nephrectomy.

•The most common histological subtype encountered is diffuse large B cell lymphoma (DLBCL).

•Lymphoma may also mimic nephroblastomatosis, however, lymphoma occurs typically in older children and is associated with lymphadenopathy elsewhere in the body.

•Imaging findings of renal lymphoma are variable and include:

–Solitary or multiple renal masses or nodules

–Diffuse infiltration

–Direct invasion from contiguous retroperitoneal extension

–Isolated perinephric disease

–The most common radiologic pattern is multiple parenchymal masses or nodules

that occasionally distort the renal contour and displace the collecting system.

–They are usually homogeneous, are hypo attenuating on nonenhanced and contrastenhanced images, and may mimic multiple renal cysts.

–At US, they are hypoechoic

–Angiography shows hypovascular mass lesions

–Diffuse infiltration of the kidney may result in reniform enlargement.

–Retroperitoneal disease occasionally leads to vascular and ureteral encasement.

–Perinephric involvement can arise from retroperitoneal disease or transcapsular spread of parenchymal involvement.

–The CT findings of perinephric disease are variable and include small curvilinear areas of high attenuation, soft-tissue attenuation nodules, thickening of the Gerota fascia, or a mass contiguous with retroperitoneal disease.

4.8.4Clinical Features

•Lymphomas are malignant tumors that are caused by lymphoid cell proliferation.

•Involvement of the kidney by lymphoma is a common late manifestation of advanced nodal disease.

•Renal involvement in non-Hodgkin’s lymphoma is usually seen as a part of disseminated disease.

•PRL is a rare and uncertain entity because renal parenchyma lacks lymphatic tissue.

•The term primary renal lymphoma is used when the disease is localized to the kidney without any sign of other organ involvement or in which renal involvement is the presenting manifestation.

•The reported incidence is as high as 47 % in autopsy series of lymphomas but clinically recognized in only up to 15 % of patients.

•In children, non-Hodgkin lymphoma especially Burkitt lymphoma is more likely to involve the kidney.