GeneraP Jean

Laperri#{232}re,

Figure

1.

MD

Transverse

#{149} Michel

(a)

Lafortune,

MD

and longitudinal

(b)

sonograms

U HISTORY An asymptomatic 48-year-old man from Santo Domingo was referred for radiobogic cxamination because of a preliminary diagnosis of hepatomegaly discovered at a physical cxamination for immigration purposes. Sonography, computed tomography (CT) , and angiography were performed (Figs 1-3). U FINDINGS Sonograms in the upper

was

terms: neoplasms,

the

partment cepted .cRSNA,

November

Kidney neoplasms, angiography, US studies, 81.1298 1990;

Department

ofRadiolog’, November 1990

1990

than

shunting. study cated

(Fig 1) showed a huge, solid mass pole of the right kidney that dis-

RadloGraphics From

less

81

.

1 24

3

kidney.

that

of the

normal

left

kidney.

No peninephric invasion on retropenitoneal adenopathy was demonstrated. Bands of lowattenuation tissue were seen radiating from the lower-attenuation center. Angiograms (Fig 3) revealed a highly vascuban mass with a radiating arterial arrangement (“spoke-wheel” appearance) ; theme was no vascular pooling on arteniovenous

The

nephmographic

showed the mass from the healthy

phase

to be clearly lower pole

of the demamof the

kidney.

placed the lower pole infemiorly. The mass had a smooth contour and an anechoic centen from which solid tissue columns radiated. On the CT scan (Fig 2), the mass exhibited a homogeneous contrast enhancement that

Index Kidney

of the right

Kidney

neoplasms.

#{149}

CT,

8 1.

1 2 1 1

Kidney

#{149}

neoplasms.

diagnosis.

8 1 . 3 19

10:1105-1107 ofRadiology.

Saint 2. Address

H#{244}tel-Dieu

de Montr#{233}al. 3840

Luc Hospital, Montreal (ML.). reprint requests toiL.

From

Rue the

St Urbain.

1989

Laperri#{234}re

RSNA

and

Montreal, scientific

Que. assembly.

Lafortune

Canada

H2W

Received

U

lT8 October

(J.L.)

and 25,

RadioGrapbics

the

1989;

De ac

U

1105

Figure

2.

3.

Arterial

Contrast-enhanced

CT scan.

a.

b.

Figure

1106

U

RadioGrapbks

(a)

and nephrographic

U

Laperri#{232}re

(b)

and

phases

Lafortune

of a selective

right

renal

arteniographic

study.

Volume

10

Number

6

DIAGNOSIS:

Oncocytoma

of the

right

kidney. U DISCUSSION Renal oncocytomas are relatively rare, benign tumors (3%-6% of all renal neoplasms). Patients with this neoplasm usually present in the 6th or 7th decade of life and usually have no symptoms (1 ) Renal oncocytomas .

are thought to have a proximal tubular epitheliab origin. About 3% are bilateral, and 5% are multicentnic within the same kidney. These tumors are well encapsulated, with a mahogany brown surface, and their diameter averages 7 cm (1) Large tumors frequently have a central scar. This scar is seen on CT scans and sonograms in about one-third of cases. Renal oncocytomas exhibit homogeneous enhancement on CT scans (2) , and one-half of them have a radiating arterial anrangement on angiograms. Necrosis, hemorrhage, and calcifications are uncommon featunes (3). In our case, examination of the resected .

specimen

showed a solid, webb-encapsulated, tannish brown tumor with a liquid, somewhat gelatinous center from which radiated columns of tumor cells. Histologically, the batter were oncocytes, that is, large epithebial cells with abundant, finely granular eosinophibic cytoplasm. The differential diagnosis for renal oncocytoma includes renal cell carcinoma, renal lymphoma, metastatic tumor, nephroblastoma, and angiomyolipoma (4) A renal cell carcinoma of this size might be expected to produce symptoms. Most renal cell carcinomas are hypenvascubar, with puddling of contrast material seen at angiography, and are as-

encountered in about one-third of patients, most often in the form of multiple nodules. Renal lymphomas are hypovasculan, enhance little on CT scans, and are usually accompanied by adenopathy or hepatospbenomegaly (4). Metastases to the kidney may originate from the lung, breast, gastrointestinal tract, thyroid, genitouninary tract (choniocancinoma) , on any site of melanoma (4) Metastatic .

lesions

with arteniovenous shunting and encasement. On CT scans, renal cell carcinoma exhibits a bobulated contour, nonhomogeneous contrast enhancement, and an

indistinct

interface

chyma (2). Primary renal renal involvement

November

1990

with

normal

renal

to infiltrate

the

kidney,

are

usu-

ally hypovascular, and are multiple and smaller than renal oncocytomas. In addition, our patient had no symptoms suggestive of a

primary

cancer

elsewhere.

Nephroblastomas

common in adults, have been reported.

neous

(Wilms

although They

enhancement

tumor)

are

un-

several cases show a heteroge-

on CT scans

due

to ne-

crotic dialing

or cystic areas and do not exhibit a raarterial arrangement as seen in our case (4). Solitary angiomyolipoma occurs more frequently in women, and the lesion does not usually reach the size of the lesion seen in our case. They characteristically contain fat, which appears hypenechoic on sonograms and is easily seen on CT scans. They are also accompanied by aneurysms, which are detected on angiograms. U REFERENCES 1 . Lafortune M, Breton

.

sociated vessel

tend

2.

3.

4.

stration

G. of an oncocytoma.

1983; Levine raphy

34:144-146. E, Huntrakoon M. of renal oncocytoma.

1985;

313:1596-1603.

Echographic demonJ Can Assoc Radiol Computed AJR 1 983

tomog-

1 4 1: 74 1-746. Wasserman NF, Ewing SL. Calcified renal oncocytoma. AJR 1983; 14 1:747-749. Scully RE, Mard EJ, McNeely BU. Bilateral oncocytomas. Massachusetts General Hospital Case Records, case 51-1985. N EnglJ Med ;

paren-

bymphoma is rare. However, in systemic bymphoma is

Laperri#{232}re

and

Lafortune

U

RadioGrapbics

U

1107