Author: Zachary Bercu
US CT MRI: T1 or T1 fat-sat MRI: T2 MRI: Post-contrast T1 or MRA Gross Pathology Histology Additional Images: IVP, Retrograde Pyelogram, Radionuclide Comments
Malignancy:
Renal Cell Carcinoma Variable. Example: Echogenic nodule (arrow) in cystic neoplasm. Unilocular cystic neoplasms tend to be papillary subtype. Image 1: NECT shows complex cystic mass w/hemorrhage (arrow) & lymphadenopathy (arrowheads).

Image 2: corticomedullary CECT shows expansile, heterogeneously enhancing renal mass (arrows) w/associated hypervascular lymphadenopathy (arrowheads).

Image 3: nephrographic CECT shows heterogeneously enhancing renal mass (arrows) with calcifications (arrowheads).

Image 4: Contrast-enhanced CT scan of a renal medullary carcinoma shows a heterogeneously enhancing right renal mass (black arrow) with associated cystic retroperitoneal lymphadenopathy (white arrows).
MR images of a 58-year-old man with high-grade clear cell RCC diagnosed at radical nephrectomy. Precontrast image is demonstrated. Axial T2-weighted MR image of a papillary RCC shows a round, uniformly hypointense tumor (arrows). Note the multiple bilateral renal cysts (arrowheads). Axial gadolinium-enhanced fat-saturated three-dimensional gradient-echo MR image of a chromophobe RCC shows a relatively hypovascular, expansile right renal mass with slightly heterogeneous enhancement (arrows).

Image 2
Gross specimen of a clear cell RCC shows variegated nodular growth (arrows) with areas of hemorrhage and necrosis (arrowheads). Photomicrograph (original magnification, ×200; hematoxylin-eosin [H-E] stain) of a clear cell RCC shows clear cells (black arrow) with prominent cell borders and prominent vasculature (blue arrow).
Lymphoma Large cell lymphoma in a 63-year-old man. Sagittal renal US image demonstrates lymphoma with a characteristic hypoechoic appearance in the lower pole of the right kidney (arrow). Perirenal lymphoma in a 64-year-old man. Helical CT scans obtained before intravenous administration of contrast material show a perirenal soft-tissue mass enveloping the left kidney.

Perirenal lymphoma in a 64-year-old man. Helical CT scans obtained after intravenous administration of contrast material show a perirenal soft-tissue mass enveloping the left kidney. The symmetric renal function seen reflects the characteristic “soft” nature of lymphomatous tumor.

Large cell lymphoma in a 73-year-old woman. Contrast-enhanced CT scan shows bilateral renal masses with characteristic homogeneous attenuation, smooth borders, and low contrast enhancement. Retroperitoneal adenopathy is also present (A).
Burkitt-like aggressive lymphoma in a 40-year-old man who presented with right flank pain and a creatinine level of 9.9. A diagnosis of HIV infection had recently been made. Axial venous phase contrast-enhanced fat-saturated T1-weighted venous phase contrast-enhanced MR image of the abdomen shows left renal lesions (thin arrows) with very little enhancement. The mass in the lower pole of the right kidney (thick arrows) has heterogeneous signal intensity. Note also the area of necrosis within the mass. Diffuse large cell lymphoma in a 38-year-old woman. Photograph of a gross specimen reveals a large, fleshy yellow tumor arising from the superior pole of the kidney (arrow). Small retroperitoneal and pelvic lymph nodes were also present at surgery. Immunohistochemical analysis of the renal mass demonstrated a staining pattern consistent with a lymphoma of B-cell origin, the most common type of lymphoma involving the kidney. High-grade B-cell lymphoma in a 38-year-old human immunodeficiency virus (HIV)–positive woman who presented with abdominal pain and distention. Photomicrograph (original magnification, ×200; Diff-Quik stain) of a specimen obtained at fine-needle aspiration biopsy shows hypercellularity with a uniform population of malignant lymphocytes. Numerous aptotic cells are also seen, a finding that is compatible with a high-grade phenotype. Recurrent B-cell lymphoma in a 19-year-old man. FDG PET (left) and CT (right) scans obtained 9 months after treatment show multiple foci of intense activity (arrows) in the right kidney.
   
Metastases Renal metastases in a 45-year-old woman with cervical carcinoma who had undergone radiation therapy. Contrast-enhanced CT scan obtained at the level of the kidneys reveals bilateral low-attenuation renal masses (arrows). A CT scan obtained 1 year earlier demonstrated normal kidneys.
             
Urothelial carcinoma (formerly Transitional cell carcinoma) Renal TCC in a 59-year-old woman. Sagittal US scan shows a tumor (arrows) in the echogenic renal sinus. Tumor tissue is more echogenic than the surrounding renal cortex but less echogenic than renal sinus fat. TCC of the renal pelvis in a 43-year-old man with flank pain and hematuria. Axial nonenhanced CT scan shows a mass (arrow) in the right renal pelvis. The mass is slightly hyperattenuating relative to the urine and renal parenchyma.

TCC of the renal pelvis in a 43-year-old man with flank pain and hematuria. Axial nephrographic phase CT scan shows that the mass (arrow) has characteristic early enhancement, which is less than that of the surrounding renal parenchyma.

TCC of the renal pelvis in a 43-year-old man with flank pain and hematuria. Axial excretory phase CT scan (bone window) shows the lesion more clearly (arrow).
Bilateral renal TCC in a 77-year-old man with hematuria. Axial T2-weighted fast spin-echo MR image (8000/104) obtained with fat saturation shows TCC in the upper poles of both kidneys (arrows) with invasion of the right renal vein and inferior vena cava (arrowhead). Bilateral ureteric TCC in a 57-year-old woman. Axial gadolinium-enhanced T1-weighted MR image (616.7/ 10) obtained with fat saturation shows enhancement of the right ureteric tumor (large arrow). Note the gadolinium contrast material in the left ureter (small arrow) above the tumor.

Ureteric TCC in a 56-year-old woman. Coronal MIP half-Fourier rapid acquisition with relaxation enhancement MR urogram (1500/116) shows hydronephrosis and a filling defect due to a tumor in the mid left ureter (arrow). Note the poor demonstration of the nondilated right collecting system.

Renal TCC in a 68-year-old woman. Gadolinium-enhanced 3D MIP MR angiogram shows the tumor more clearly. Note the retroaortic segment of the left renal vein.
Ureteric TCC in a 58-year-old man. RP image shows a duplex right collecting system. TCC in the midportion of the ureter draining the upper pole moiety produces the characteristic goblet sign (straight arrow). Another tumor is identified in the ureter draining the lower pole moiety (curved arrow).
     
Wilm's tumor Wilms tumor in a 4-year-old boy with an abdominal mass. CT scan shows a left renal mass with heterogeneous enhancement (thick arrow) and multiple hepatic metastases (thin arrows). large, well-defined mass in the right kidney (arrows) enhances less than adjacent renal parenchyma and contains multiple hypointense hemorrhagic foci. Heterogenously hyperintense mass (arrows). Wilms tumor. Photograph of a gross specimen shows a lesion that extends into the renal pelvis. The lesion has a pseudocapsule, and its surface is divided by septa. Photomicrograph (original magnification, ×62.5; hematoxylin-eosin stain) shows the triphasic pattern of stromal (curved arrow), blastemal (straight arrow), and tubular (arrowhead) elements.
       
Nephroblastomatosis Nephroblastomatosis in a 16-month-old boy with an abdominal mass. Contrast-enhanced CT scan shows large, homogeneous Wilms tumors (W) superimposed on a background of multiple peripheral nephrogenic rests (arrowheads). Hyperplastic perilobar nephroblastomatosis. Photograph of a gross specimen shows diffuse overgrowth of peripheral mesoblastic tissue, which causes loss of corticomedullary differentiation and nephromegaly with preservation of reniform shape.
           
Mesoblastic Nephroma US image shows a complex but predominantly cystic heterogeneous lesion (*) arising from the left kidney. Axial contrast-enhanced CT scan through the abdomen shows a complex but predominantly cystic left flank mass arising from the anterior cortex of the left kidney. Photograph of the cut surface of the gross specimen shows a heterogeneous, unencapsulated mass (arrows) infiltrating the anterior renal cortex, with extension beyond the capsule and invasion of the sinus fat. Scale is in centimeters. (a) Photomicrograph (original magnification, ×100; hematoxylin-eosin stain) shows a highly cellular tumor with no intervening normal renal tissue. The cells are spindle shaped and arranged in fascicles. Inset (original magnification, ×400; hematoxylin-eosin stain) shows similar findings.
       
Infection:
Pyelonephritis Acute bacterial pyelonephritis. US scan shows a wedge-shaped hyperechoic focus (arrowhead) in the upper pole of the right kidney related to acute bacterial pyelonephritis.

Acute bacterial pyelonephritis. Color flow US image demonstrates diminished flow through the involved area.
Acute bacterial pyelonephritis. (7) Unenhanced CT scan from a clinically documented case of acute bacterial pyelonephritis shows asymmetric enlargement and absence of the pyramids of the right kidney (cf the preserved pyramids [arrow] in the normal left kidney). Loss of the renal pyramids is a nonspecific marker for edema, which is more typically seen in obstruction related to calculi.

Severe unilateral acute bacterial pyelonephritis.CT scan shows the enlarged kidney with global decreased uptake of contrast material and multiple small low-attenuation foci from abscess pockets, findings that prompted nephrectomy.

Masslike appearance of acute bacterial pyelonephritis. CT scan shows multifocal regions of diminished enhancement that extend to the periphery of the kidney, findings consistent with interstitial nephritis.
Severe unilateral acute bacterial pyelonephritis. Photograph of the resected gross specimen reveals multiple intrarenal abscesses that have begun to partially coalesce. Scale is in centimeters. Scintiscan obtained with technetium 99m dimercaptosuccinic acid demonstrates a photopenic, peripheral defect (arrow) in the upper lateral margin of the right kidney that correlates with an area of acute bacterial pyelonephritis.
       
Abscess Renal abscess in a 32-year-old woman with a history of fever and flank pain. Axial contrast-enhanced CT image shows a 3-cm cystic mass with a thick irregular wall arising from the lower pole of the left kidney. Note the significant inflammatory reaction and thickening of the perirenal fascia, findings highly suggestive of an inflammatory process. A renal abscess was diagnosed, and the patient was successfully treated with intravenous antibiotics. Even without a history suggestive of infection, the marked perirenal reactive changes should strongly suggest an abscess, and needle aspiration should be performed for diagnosis and possible drainage.
             
Tuberculosis Unenhanced CT scan shows two large calcifications in the medial upper pole of the right kidney (arrows).

Contrast-enhanced nephrographic-phase CT scan shows dilated calices and thinning of the renal cortex (arrow).

Magnified view from a contrast-enhanced nephrographic-phase CT scan obtained caudad to a shows mural enhancement and thickening of the proximal ureter (arrow).

Contrast-enhanced excretory-phase CT scan shows dilated calices and narrowing of the infundibula (arrowheads).

Contrast-enhanced excretory-phase CT scan obtained at the level of the midureter shows circumferential ureteral wall thickening (arrow). The left ureter is normal (arrowhead).
Photograph of the bivalved resected specimen shows two foci of caseous necrosis in the upper pole (arrows). Low-power photomicrograph (original magnification, ×10; hematoxylin-eosin stain) shows focal caseating granulomas (arrows) and sheets of chronic interstitial inflammation (arrowhead). Retrograde ureteropyelogram shows globular calcific areas of increased opacity in the medial upper pole of the right kidney (arrowheads). The calices are markedly enlarged with ill-defined margins (white arrows). Small, irregular collections of extracaliceal contrast material are also present (black arrows).

Magnified view from a retrograde ureteropyelogram of the right ureter shows mucosal irregularities and erosions (arrowheads).
       
HIV/HAART nephropathy Longitudinal US image shows the characteristic features of HIV-associated nephropathy, including increased renal size, increased parenchymal echogenicity (white arrow), and loss of renal sinus fat. Black arrow indicates the renal pyramid. HAART-related nephropathy in a patient with HIV infection and hypertension. MR angiograms show bilateral renal artery stenosis. The patient had previously had normal blood pressure along with hypertension, with bilateral renal artery stenosis occurring only after the initiation of HAART. Stent placement and repeat imaging can be used to prove the correlation.

HAART-related nephropathy in a patient with HIV infection and hypertension. MR angiograms show bilateral renal artery stenosis. The patient had previously had normal blood pressure along with hypertension, with bilateral renal artery stenosis occurring only after the initiation of HAART. Stent placement and repeat imaging can be used to prove the correlation.

HAART-related nephropathy in a patient with HIV infection and hypertension. MR angiograms show bilateral renal artery stenosis (arrows in b). The patient had previously had normal blood pressure along with hypertension, with bilateral renal artery stenosis occurring only after the initiation of HAART. Stent placement and repeat imaging can be used to prove the correlation.
HAART-related nephropathy in a 64-year-old HIV-positive patient who presented with loin pain and hematuria. The patient had been taking indinavir as part of an antiretroviral regimen for 2 years. CT and US demonstrated scarring of the left upper pole with no cause identified. Bone scintigrams obtained with dimercaptosuccinic acid reveal renal scarring in the left upper pole (arrow), a finding that was presumed to be secondary to an indinavirinduced calculus. The patient recovered clinically, and the radiologic findings did not progress after indinavir was replaced with another antiretroviral agent. Photomicrograph (original magnification, ×200; H-E stain) shows collapsing glomerulopathy (HIV-associated nephropathy). The glomerular tuft is collapsed and solid, with prominent visceral epithelial cells (podocytes) (arrowheads) and Bowman space (*).
       
Xanthogranulomatous pyelonephritis Xanthogranulomatous pyelonephritis. US scan also shows the dilated collecting system (arrowheads) and a shadowing calculus (arrow). Xanthogranulomatous pyelonephritis. Contrast-enhanced CT scan demonstrates bilateral staghorn calculi, with distention of the right collecting system secondary to inflammatory debris.

Focal xanthogranulomatous pyelonephritis. Contrast-enhanced CT scan demonstrates a thick-walled, peripherally enhancing, low-attenuation lesion.
Xanthogranulomatous pyelonephritis in a 32-year-old woman with diabetes and Proteus infection of the urinary tract. Coronal steady-state fast spin-echo T2-weighted MR image shows a poorly defined mass (arrowheads) in the lower pole of the right kidney and hydronephrosis (arrows) in the upper pole. Contrast-enhanced CT scan demonstrates a thick-walled, peripherally enhancing, low-attenuation lesion. (b) Coronal contrast-enhanced T1-weighted MR image demonstrates the lesion with very similar characteristics.

Xanthogranulomatous pyelonephritis in a 32-year-old woman with diabetes and Proteus infection of the urinary tract. Axial contrast-enhanced 3D nephrographic phase fat-saturated GRE T1-weighted MR image shows irregular areas of enhancement extending into the perinephric space (arrowheads). The hypointense areas in the central region of the kidney (arrows) correspond to portions of a large staghorn calculus, which was better visualized at unenhanced CT. The appropriate clinical history and characteristic imaging findings strongly suggest the diagnosis of xanthogranulomatous pyelonephritis, which was confirmed at nephrectomy in this case.
Xanthogranulomatous pyelonephritis. Photograph of a cut specimen clearly depicts a complex, milky infiltrate that fills and expands the collecting system.

Focal xanthogranulomatous pyelonephritis. Photograph of the cut specimen shows the thick-walled, yellowish capsule of the focal lesion.
Focal xanthogranulomatous pyelonephritis. Photomicrograph (original magnification, ×400; hematoxylineosin stain) shows a large collection of foamy macrophages and histiocytes (arrowhead). Xanthogranulomatous pyelonephritis with staghorn calculus. Abdominal radiograph shows a classic staghorn calculus secondary to xanthogranulomatous pyelonephritis in the location of the right kidney.
 
Congenital:
Autosomal recessive PKD Pattern of contrast material enhancement in ARPKD in an adolescent with mild renal insufficiency. (a) Axial unenhanced CT scan shows a normal-sized right kidney with a small calcification (arrow). (b) Axial CT scan obtained immediately after intravenous injection of contrast material shows prompt peripheral enhancement.

Severe ARPKD in a newborn. Axial CT scan obtained after intravenous administration of contrast material shows large, smooth, low-attenuation kidneys (arrowheads). There is faint, streaky enhancement secondary to the infant's renal failure, resulting in poor perfusion and excretion of contrast material.

Pattern of contrast material enhancement in ARPKD in an adolescent with mild renal insufficiency. (a) Axial unenhanced CT scan shows a normal-sized right kidney with a small calcification (arrow). (b) Axial CT scan obtained immediately after intravenous injection of contrast material shows prompt peripheral enhancement. (c) A 15-minute delayed image reveals streaks of high attenuation in the renal parenchyma, oriented radially from the renal pelvis. This finding represents excreted contrast material pooling in dilated collecting ducts.
Photograph of a bivalved kidney involved with ARPKD reveals multiple ectatic collecting ducts, radially oriented from the center of the kidney to the surface. The corticomedullary junction is obliterated by the numerous abnormal ducts. Histologic features of the kidney in ARPKD. Low-power photomicrograph (original magnification, × 20; hematoxylineosin stain) of a renal specimen involved with ARPKD shows radially oriented, dilated collecting ducts (*) abutting the renal capsule (arrowheads). Normal glomeruli are interspersed among the dilated collecting ducts (arrows). Mild ARPKD in a 16-year-old adolescent with normal renal function. Excretory urogram shows kidneys of normal size but some striation of the nephrograms bilaterally.
       
Autosomal dominant PKD Autosomal dominant polycystic kidney disease. Coronal T2-weighted MR image shows enlargement of both kidneys with multiple expansile renal cysts (arrows), as well as multiple hepatic cysts (arrowheads).
             
Benign Tumor:
Angiomyolipoma Angiomyolipoma in a 54-year-old woman. Axial in-phase GRE T1-weighted MR image shows a large mass (M) arising from the lower pole of the right kidney (K). The mass has higher signal intensity than the renal parenchyma.

Angiomyolipoma in a 54-year-old woman. Axial opposed-phase GRE T1-weighted MR image shows a mild decrease in signal intensity in some areas of the mass due to the intravoxel coexistence of fat and water protons. However, there is persistent high signal intensity in other areas of the mass, a finding that suggests the presence of bulk fat. A characteristic “India ink” artifact is seen at the fat-water interface between the mass and the kidney (arrow). Note that this artifact is not present in the exophytic portion of the mass (arrowheads), which represents a fat-fat interface between retroperitoneal fat and fat in the mass itself.

Angiomyolipoma in a 54-year-old woman. Axial 3D GRE T1-weighted MR image obtained with frequency-selective fat saturation shows diffuse suppression of signal intensity within the mass (M), thereby helping confirm the presence of bulk fat. Demonstration of bulk fat in a renal mass is virtually diagnostic for angiomyolipoma.
Lipid-poor angiomyolipoma in a 54-year-old woman. Photomicrograph (original magnification, ×10; H-E stain) shows the mass composed of smooth muscle surrounding thick-walled vessels, along with rare, scattered mature adipocytes (arrowheads), findings that are consistent with an angiomyolipoma. Making the diagnosis of angiomyolipoma at MR imaging is virtually impossible in the absence of detectable macroscopic fat. Clear cell RCC should be included in the differential diagnosis when only intracellular fat is visualized.
           
Oncocytoma Oncocytoma in a 42-year-old woman. Coronal single-shot fast spin-echo MR image shows a large, well-defined mass with heterogeneous signal intensity and a central cleft (arrow). Oncocytoma in a 42-year-old woman. Coronal contrast-enhanced nephrographic phase MR images show the mass with heterogeneous enhancement. The central cleft (arrow) is enhanced on the delayed image, thereby excluding necrosis. There are no features to reliably help distinguish oncocytoma from RCC. Oncocytoma was confirmed at histopathologic analysis performed after left nephrectomy.

Oncocytoma in a 42-year-old woman. Coronal contrast-enhanced delayed excretory phase MR images show the mass with heterogeneous enhancement. The central cleft (arrow) is enhanced on the delayed image, thereby excluding necrosis. There are no features to reliably help distinguish oncocytoma from RCC. Oncocytoma was confirmed at histopathologic analysis performed after left nephrectomy.
           
Multilocular cystic nephroma Sagittal US image of the left renal fossa demonstrates a multicystic mass with variably sized cystic components and thin echogenic septa. Axial enhanced CT image shows a large, low-attenuation mass with multiple thin septations arising from the left kidney. The mass extends into the renal pelvis (black arrow). Residual normal renal parenchyma is seen (white arrow), and there is a thin claw of renal parenchyma extending around part of the mass (arrowheads). Photograph of the cut surface of the resected left kidney and mass shows multiple smooth-walled cysts separated by thin translucent septa. A portion of the mass has prolapsed into the renal pelvis (white arrows). Note the residual normal renal parenchyma (yellow arrow) and the claw sign (arrowheads). Scale is in centimeters. Photomicrograph (original magnification, ×20; hematoxylin-phloxin-saffron [HPS] stain) shows the edge of the multicystic mass (arrowhead) and adjacent compressed renal parenchyma (arrow). Radiograph of the abdomen demonstrates a large soft-tissue–density mass occupying the left side of the abdomen, extending across the midline, and displacing and effacing adjacent bowel loops.
     
Other:
Cyst Anechoic, thin-walled. Fluid attenuating lesion. May demonstrate calcification.

Non-enhancing fluid-attenuating lesion.
Use of MR imaging to evaluate the relative enhancement of a hyperattenuating and high-signal-intensity cyst in a 53-year-old asymptomatic man. CT demonstrated a 3-cm-diameter hyperattenuating (40 HU) lesion in the left kidney. Serial precontrast (pictured here), corticomedullary phase (see "T1 post-contrast"), and nephrographic phase (see "T1 post-constrast") T1-weighted breath-hold gradient-echo MR images show no significant enhancement of the lesion, with relative signal intensities of 138, 138, and 139, respectively. Use of MR imaging to evaluate the relative enhancement of a hyperattenuating and high-signal-intensity cyst in a 53-year-old asymptomatic man. CT demonstrated a 3-cm-diameter hyperattenuating (40 HU) lesion in the left kidney. Serial precontrast (see "T1"), corticomedullary phase (pictured here), and nephrographic phase (see below) T1-weighted breath-hold gradient-echo MR images show no significant enhancement of the lesion, with relative signal intensities of 138, 138, and 139, respectively.

Use of MR imaging to evaluate the relative enhancement of a hyperattenuating and high-signal-intensity cyst in a 53-year-old asymptomatic man. CT demonstrated a 3-cm-diameter hyperattenuating (40 HU) lesion in the left kidney. Serial precontrast (see "T1"), corticomedullary phase (see above), and nephrographic phase (pictured here) T1-weighted breath-hold gradient-echo MR images show no significant enhancement of the lesion, with relative signal intensities of 138, 138, and 139, respectively
Photograph shows a hemorrhagic cyst. Cystic lesion (arrow) contains fluid and thick, irregular cyst wall. Definitive diagnosis is dependent on microscopic examination.
     
Column of Bertin Acute renal cortical necrosis. Axial T2-weighted MR image (2,000/80) obtained at 2.0 T on the 30th day of renal cortical necrosis shows that both kidneys are shrunken and the low-signal-intensity cortex and columns of Bertin are prominent (see "T2"). The low-signal-intensity line (arrows) along the lateral margin of the right kidney is due to chemical shift artifact. Nonenhanced CT scan (pictured here) shows diffuse calcification involving the renal cortex and the columns of Bertin, which causes the low signal intensity on MR images. Acute renal cortical necrosis. Axial T2-weighted MR image (2,000/80) obtained at 2.0 T on the 30th day of renal cortical necrosis shows that both kidneys are shrunken and the low-signal-intensity cortex and columns of Bertin are prominent (pictured here). The low-signal-intensity line (arrows) along the lateral margin of the right kidney is due to chemical shift artifact. Nonenhanced CT scan (see "Non-enhanced CT") shows diffuse calcification involving the renal cortex and the columns of Bertin, which causes the low signal intensity on MR images. Normal neonatal kidney. Longitudinal gross anatomic section shows that the pyramids appear large compared with the relatively thin cortex and columns of Bertin; this appearance is characteristic of normal neonatal kidneys. Indentations of the cortex (arrowheads) in the region of the columns of Bertin represent fetal lobulations. Both the cortex and medulla are striated due to the vasculature in the former and a combination of vessels and collecting ducts in the latter. The collecting system appears white. Note the extensions of the fornices of the calices (arrows) surrounding the apex of the papillae.
         
Amyloidosis Amyloidosis in a 59-year-old woman with slowly progressive renal insufficiency. Sagittal US image shows diffuse increased echogenicity in the renal cortex with a renal size at the top limit of normal. Biopsy results were diagnostic of amyloidosis. Primary amyloidosis in a 62-year-old woman with right flank pain. Axial CT image shows a small cortical mass with focal calcifications in the right kidney (arrow). Biopsy demonstrated amyloid infiltration.