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## Complete Summary

#### GUIDELINE TITLE

Indeterminate renal masses.

#### BIBLIOGRAPHIC SOURCE(S)

Israel GM, Francis IR, Baumgarten DA, Bluth EI, Bush WH Jr., Casalino
DD, Curry NS, Jafri SZ, Kawashima A, Papanicolaou N, Remer EM, Sandler
CM, Spring DB, Fulgham P, Expert Panel on Urologic Imaging.
Indeterminate renal mass. \[online publication\]. Reston (VA): American
College of Radiology (ACR); 2007. 7 p. \[65 references\]

#### GUIDELINE STATUS

This is the current release of the guideline.

This guideline updates a previous version Francis IR, Choyke PL, Bluth
E, Bush WH Jr, Casalino DD, Jafri SZ, Kawashima A, Kronthal A, Older RA,
Papanicolaou N, Ramchandani P, Rosenfield AT, Sandler C, Segal AJ,
Tempany C, Resnick MI, Expert Panel on Urologic Imaging. Indeterminate
renal masses. \[online publication\]. Reston (VA): American College of
Radiology (ACR); 2005. 7 p. \[54 references\]

The appropriateness criteria are reviewed annually and updated by the
panels as needed, depending on introduction of new and highly
significant scientific evidence.

### \*\* REGULATORY ALERT \*\*

#### FDA WARNING/REGULATORY ALERT

**Note from the National Guideline Clearinghouse**: This guideline
references a drug(s) for which important revised regulatory and/or
warning information has been released.

-   [May 23, 2007, Gadolinium-based Contrast
    Agents](http://www.fda.gov/medwatch/safety/2007/safety07.htm#Gadolinium):
    The addition of a boxed warning and new warnings about the risk of
    nephrogenic systemic fibrosis (NSF) to the full prescribing
    information for all gadolinium-based contrast agents (GBCAs).

### COMPLETE SUMMARY CONTENT

 \*\* REGULATORY ALERT \*\*\
 SCOPE\
 METHODOLOGY - including Rating Scheme and Cost Analysis\
 RECOMMENDATIONS\
 EVIDENCE SUPPORTING THE RECOMMENDATIONS\
 BENEFITS/HARMS OF IMPLEMENTING THE GUIDELINE RECOMMENDATIONS\
 QUALIFYING STATEMENTS\
 IMPLEMENTATION OF THE GUIDELINE\
 INSTITUTE OF MEDICINE (IOM) NATIONAL HEALTHCARE QUALITY REPORT
CATEGORIES\
 IDENTIFYING INFORMATION AND AVAILABILITY\
 DISCLAIMER

### SCOPE

#### DISEASE/CONDITION(S)

Indeterminate renal mass

#### GUIDELINE CATEGORY

Diagnosis\
Evaluation

#### CLINICAL SPECIALTY

Nephrology\
Nuclear Medicine\
Oncology\
Radiation Oncology\
Radiology\
Urology

#### INTENDED USERS

Health Plans\
Hospitals\
Managed Care Organizations\
Physicians\
Utilization Management

#### GUIDELINE OBJECTIVE(S)

To evaluate the appropriateness of radiologic examinations for patients
with an indeterminate renal mass

#### TARGET POPULATION

Adults with an indeterminate renal mass

#### INTERVENTIONS AND PRACTICES CONSIDERED

1.  X-ray intravenous urography

2.  Ultrasound (US) Doppler duplex of the kidney

3.  Computed tomography (CT) of the kidney with and without contrast

4.  Magnetic resonance imaging (MRI) of the kidney with and without
    contrast

5.  Nuclear medicine (NUC) scan with dimercaptosuccinic acid (DMSA) of
    the kidney

6.  Invasive angiography of the kidney

7.  Invasive biopsy and aspiration of the kidney

#### MAJOR OUTCOMES CONSIDERED

Utility of radiologic procedures in evaluation of indeterminate renal
mass

### METHODOLOGY

#### METHODS USED TO COLLECT/SELECT EVIDENCE

Searches of Electronic Databases

#### DESCRIPTION OF METHODS USED TO COLLECT/SELECT THE EVIDENCE

The guideline developer performed literature searches of peer-reviewed
medical journals, and the major applicable articles were identified and
collected.

#### NUMBER OF SOURCE DOCUMENTS

Not stated

#### METHODS USED TO ASSESS THE QUALITY AND STRENGTH OF THE EVIDENCE

Weighting According to a Rating Scheme (Scheme Not Given)

#### RATING SCHEME FOR THE STRENGTH OF THE EVIDENCE

Not stated

#### METHODS USED TO ANALYZE THE EVIDENCE

Systematic Review with Evidence Tables

#### DESCRIPTION OF THE METHODS USED TO ANALYZE THE EVIDENCE

One or two topic leaders within a panel assume the responsibility of
developing an evidence table for each clinical condition, based on
analysis of the current literature. These tables serve as a basis for
developing a narrative specific to each clinical condition.

#### METHODS USED TO FORMULATE THE RECOMMENDATIONS

Expert Consensus (Delphi)

#### DESCRIPTION OF METHODS USED TO FORMULATE THE RECOMMENDATIONS

Since data available from existing scientific studies are usually
insufficient for meta-analysis, broad-based consensus techniques are
needed for reaching agreement in the formulation of the appropriateness
criteria. The American College of Radiology (ACR) Appropriateness
Criteria panels use a modified Delphi technique to arrive at consensus.
Serial surveys are conducted by distributing questionnaires to
consolidate expert opinions within each panel. These questionnaires are
distributed to the participants along with the evidence table and
narrative as developed by the topic leader(s). Questionnaires are
completed by the participants in their own professional setting without
influence of the other members. Voting is conducted using a scoring
system from 1 to 9, indicating the least to the most appropriate imaging
examination or therapeutic procedure. The survey results are collected,
tabulated in anonymous fashion, and redistributed after each round. A
maximum of three rounds is conducted and opinions are unified to the
highest degree possible. Eighty percent agreement is considered a
consensus. This modified Delphi technique enables individual, unbiased
expression, is economical, easy to understand, and relatively simple to
conduct.

If consensus cannot be reached by this Delphi technique, the panel is
convened and group consensus techniques are utilized. The strengths and
weaknesses of each test or procedure are discussed and consensus reached
whenever possible. If \"No consensus\" appears in the rating column,
reasons for this decision are added to the comment sections.

#### RATING SCHEME FOR THE STRENGTH OF THE RECOMMENDATIONS

Not applicable

#### COST ANALYSIS

A formal cost analysis was not performed and published cost analyses
were not reviewed.

#### METHOD OF GUIDELINE VALIDATION

Internal Peer Review

#### DESCRIPTION OF METHOD OF GUIDELINE VALIDATION

Criteria developed by the Expert Panels are reviewed by the American
College of Radiology (ACR) Committee on Appropriateness Criteria.

### RECOMMENDATIONS

#### MAJOR RECOMMENDATIONS

**ACR Appropriateness Criteria®**

**Clinical Condition: Indeterminate Renal Mass**

  -----------------------------------------------------------------------------------
  **Radiologic          **Rating**   **Comments**                      **RRL\***
  Procedure**                                                          
  --------------------- ------------ --------------------------------- --------------
  MRI kidney without    9            Either CT or MR is appropriate.   None
  and with contrast                  See comments regarding contrast   
                                     in text under \"Anticipated       
                                     Expectations.\"                   

  CT kidney without and 9            Either CT or MR is appropriate.   High
  with contrast                      Thin-section CT.                  

  US kidney duplex      8            To clarify mass seen on IVP that  None
  Doppler                            is probably cystic or to clarify  
                                     mass seen on CT that is probably  
                                     a hyperdense cyst.                

  INV biopsy and        5            Depends on clinical scenario--the IP
  aspiration kidney                  appearance and size of mass       

  MRI kidney without    3            Can be useful to characterize     None
  contrast                           simple cysts.                     

  NUC DMSA scan kidney  3            May be useful to rule out         Low
                                     pseudomass of functioning renal   
                                     tissue.                           

  INV angiography       3            To rule out arterio-venous        IP
  kidney                             malformation, arterio-venous      
                                     fistula, or renal artery          
                                     aneurysm.                         

  X-ray intravenous     2            May be helpful to differentiate   Low
  urography                          parenchymal from collecting       
                                     system masses.                    

  CT kidney without     1                                              Med
  contrast                                                             

  **[Rating                                                            **\*Relative
  Scale]{.underline}:                                                  Radiation
  1=Least appropriate,                                                 Level**
  9=Most appropriate**                                                 
  -----------------------------------------------------------------------------------

**Note**: Abbreviations used in the table are listed at the end of the
\"Major Recommendations\" field.

**Summary of Literature Review**

**Introduction**

An indeterminate renal mass is one that cannot be diagnosed confidently
as benign or malignant at the time it was discovered. Lesions or masses
whose character and type are clearly defined by the first imaging test
will not be discussed in this review.

In years past, discovery of a renal mass by excretory urography led to
angiography, needle aspiration, or even exploratory surgery to
characterize it accurately. The advent of ultrasonography (US) helped
resolve many masses found at urography by identifying them clearly as
simple cysts. Contrast-enhanced computed tomography (CT) has eliminated,
to a great degree, the need for angiographic evaluation of renal mass
lesions. Magnetic resonance imaging (MRI) of renal masses with fast scan
techniques and intravenous (IV) gadolinium now provides imaging
comparable to CT scanning. Radionuclide scintigraphy has in the past
been helpful in identifying lobulated functioning renal tissue
resembling a more ominous mass, but has limited applications now. The
use of needle aspiration has declined as imaging techniques have
improved.

**Urography**

The plain abdominal film has very poor sensitivity and specificity for
evaluating a renal mass. Intravenous pyelography (IVP) with
nephrotomography has only 67% sensitivity in detecting renal masses 3 cm
or less in diameter, and without tomography, the sensitivity is even
less. In a small series by one group of researchers over half of small
tumors were not visualized or were missed on the initial IVP. IVP also
lacks specificity in separating benign from malignant cystic masses.
However, the IVP continues to be an effective single test for imaging
renal function, renal anatomy, and collecting system integrity. It has
value in imaging the upper urinary collecting tracts, particularly in
the patient with lower-tract transitional neoplasm. CT urography is
being used in many centers to evaluate patients with hematuria, as it
provides a comprehensive evaluation of the urinary tract and not only
can detect renal calculi and masses but also can evaluate the urothelial
tract for causes of hematuria.

**Ultrasonography**

The most common renal mass is a cyst, and US provides the most
cost-effective method of defining and confirming a benign cyst. Factors
limiting US include the patient\'s body habitus, lesion location,
multiple lesions, and calcification in the wall of a cystic mass and
hemorrhagic fluid in a cystic mass. Early studies have suggested that US
may have a problem in detecting small (\<3 cm) renal masses. A more
recent study of von Hippel-Lindau patients using grayscale US detected
only 70% of renal masses \<2 cm, in contrast to CT which showed 95% of
the lesions. However, more recent studies using color and power Doppler
imaging have shown improved and promising results. In one study of 114
patients, phase-inversion harmonic imaging when combined with B-mode
sonography improved lesion conspicuity as well as accuracy in tissue
characterization.

Contrast-enhanced Doppler US using intravenously administered contrast
agents has also been shown to have the potential to improve the
detection and characterization of renal cell carcinomas, but it is not
widely available in the United States. In a small series, US failed to
find or accurately characterize 40% of small (\<3 cm) renal cell
carcinomas. Conversely, in a report of a much larger series sonography
had a sensitivity of 79% in detecting small renal carcinomas 3 cm or
less in diameter. In the future, color Doppler flow imaging with an IV
contrast agent may improve sensitivity in detecting tumor vessels and
evaluating the renal vein.

Previously, sonographic findings of a small hyperechoic mass were
considered diagnostic of angiomyolipoma; however, a large series by one
group of researchers showed that 61% of small (3 cm or less) solid renal
cell carcinomas were hyperechoic relative to normal renal echogenicity,
and therefore US cannot be used to definitively make the diagnosis of
angiomyolipoma. One finding suggestive of a small-renal-cell carcinoma
was a hypoechoic rim about the solid tumor. Doppler US has been
suggested as a way to further characterize solid masses; in the absence
of clinical evidence of infection, a Doppler frequency shift greater
than 2.5 kHz is advocated by some as a reliable indicator of malignancy.
However, US can be falsely negative with avascular tumor masses and
falsely positive with inflammatory masses.

Renal cysts are the most commonly discovered renal masses, and the
criteria for US diagnosis of renal cysts are well defined. These
criteria include that the mass is sonolucent, demonstrates good
through-transmission of the sound waves with posterior enhancement, and
has a thin, well-defined wall. Complex masses not fulfilling the
criteria of cysts are considered indeterminate and require further
evaluation, usually by CT.

**Computed Tomography**

The accepted criteria of a benign simple cyst are well defined. Bosniak
has developed a CT classification system for cystic renal masses,
encompassing the spectrum from simple renal cyst to obvious cystic
malignancy. A cyst that contains simple fluid, has a hairline-thin wall,
does not contain septa or calcification, and does not enhance with IV
contrast is category I, a benign cyst. Category II cysts have a
hairline-thin wall and may contain a few hairline-thin septa.
Hairline-thin calcification or a short segment of slightly thickened but
smooth calcification may be seen in category II lesions. These lesions
do not show measurable enhancement with IV contrast. High-attenuation
cysts are also included in category II. Initial reports indicated that
category II cysts are invariably benign. The hyperdense cyst can also
present a diagnostic problem in that its initial attenuation
coefficients are high \[50-90 Hounsfield units (HU)\] which can
theoretically obscure tiny papillary projections along its wall. US may
be useful in characterizing some of these high-attenuation lesions as
approximately, 50% of these will be anechoic and can be characterized as
benign.

While US is superior to CT in depicting the internal features of cystic
renal masses, the presence of calcium can obscure other features. In
these instances, CT can be useful to characterize these lesions, as the
presence of a small amount of calcium does not hinder characterization.

Category IIF cysts are those cystic renal masses that are felt to be
benign but are too complex to be diagnosed with absolute certainty. They
have one or more of the following abnormalities: increased number of
hairline septa; minimal thickening of cyst wall or septa, which may
demonstrate perceived (not measurable) enhancement of septa or cyst
wall; calcification, which may be thick and nodular; no enhancing
soft-tissue components; and totally intrarenal high-attenuation lesions
3 cm or more in size. These lesions, in view of their complexity when
compared to category II lesions, warrant follow-up (usually at 6-month
intervals for the first year, and then annually for a minimum of 5
years), to assure stability. One study reported a series of 42 category
IIF lesions with a minimum of 2-year follow-up and showed that most of
them were stable (greater than 5-year mean follow-up) and only in two
cases did the lesion become more complex and subsequently prove to be
renal cell carcinoma.

Category III lesions have grossly thickened walls or septa in which
measurable enhancement can be demonstrated. Malignancy cannot be
excluded in these cases, and surgery is generally suggested.

Initially, it was felt that about half of category III cystic lesions
will be malignant, but reported percentages vary from 25%-100%. However,
with the introduction of category IIF, some lesions that were initially
felt to be category III are now considered category IIF and are
followed, in lieu of surgery. Therefore, the overall percentage of
malignancy within category III is felt to have increased.

Identification of enhancement after IV contrast is a key determinant in
characterizing a renal mass as potentially malignant. CT is the most
important imaging technique for evaluating the indeterminate renal mass.
Images acquired before and after contrast are critical to define the
lesion; enhancement indicates a vascularized mass and, therefore, a
possible malignancy. Initially, enhancement of more than 10 HU was
considered by Bosniak and others to be significant. However, with the
introduction of helical CT scanners, others suggest an increase of 20 HU
to be indicative of enhancement. Sensitivity of CT in identifying small
renal masses is greater than 90%. Analysis of enhancement for neoplasm
is best done in the nephrographic phase of helical CT imaging of the
kidneys. False negatives may occur in the corticomedullary phase.

Although the Bosniak classification scheme is very useful for the
clinical management of cystic renal masses, interobserver variation in
distinguishing between category II, IIF, and III lesions does exist and
may present problems in recommending surgical versus conservative
management in some cases. In one study 11 (16%) of 70 cystic lesions
classified as category I or II by one reader were upgraded to category
III or IV by another reader.

CT enables detection of small amounts of fat that identifies the lesion
as a benign angiomyolipoma. Fat related to other malignant neoplasms has
been reported, but these masses are generally large tumors that had
engulfed perinephric or renal sinus fat, or renal carcinomas that had
areas of osseous metaplasia and small amounts of fat. Macroscopic fat
within a noncalcified mass remains specific for benign angiomyolipoma.
For angiomyolipomas that do not contain macroscopic fat, chemical shift
MRI may suggest the diagnosis by demonstrating loss of signal on the
opposed-phase images. However, clear-cell renal cell carcinoma may also
lose signal on opposed-phase MRI images, and therefore the diagnosis of
an angiomyolipoma that does not contain macroscopic fat cannot be made
with absolute certainty with CT or MRI.

Oncocytomas cannot be diagnosed based on their imaging appearance. The
CT finding of a central scar, previously felt to be specific for
oncocytoma, has been found with renal cell carcinomas, and the finding
is not specific. As reported by one group of researchers CT findings of
homogeneity or a central stellate \"scar\" are poor discriminators in
predicting oncocytoma or renal cell carcinoma, regardless of size.

The small (1.5 cm or less in diameter) renal mass poses a more complex
problem for CT imaging, in that volume-averaging effects occur, making
it difficult to assess accurately the density on noncontrast images and
to evaluate for enhancement after IV contrast administration. Among the
more difficult entities to differentiate from a small renal cell
carcinoma are a small dense cyst containing blood or proteinaceous
material and a simple cyst that demonstrates pseudo enhancement.
Multidetector CT using thin overlapping reconstructions may help improve
characterization of small renal masses. In a recent multidetector CT
study of 37 patients with 175 small (\<3 cm) renal masses, thin
overlapping reconstructions were performed and compared to routine 5 mm
thick sections to determine if the thin overlapping reconstructions
could improve detection and characterization of small renal masses.
Lesion characterization for cysts improved from 29%-84% when thin
overlapping reconstructions were used, and the overall percentage of
indeterminate lesions was reduced from 69% to 53%.

Very small solid renal nodules are common; in one study more than 50% of
patients had some type of very small renal nodule at necropsy, and about
one-third of these were termed \"adenomas.\" The small renal adenoma is
currently considered to be a \"renal adenocarcinoma of low metastatic
potential.\" The low metastatic potential of small renal cell carcinomas
(less than 3 cm in diameter) is supported by many series. In the elderly
or in a patient who is a poor surgical risk, Bosniak feels that a small
(less than 1.5 cm diameter) indeterminate renal mass can be followed
until it reaches 2 cm in diameter. Although a solid lesion up to 3 cm in
diameter has low metastatic potential, once it has been characterized as
a solid, non-fat-containing mass it should be considered and potentially
treated as a malignancy. If the patient\'s clinical condition militates
against surgery or if there is surgical risk of causing the patient to
become dialysis-dependent, such lesions, because of their low metastatic
potential when small, can be followed with CT or MRI. Surgery is
reconsidered if the mass shows rapid growth.

The effect of early detection of a very small renal mass by current
technology operates insidiously to alter our perception of how
radiological tests affect patient care, especially the detection and
management data affected by \"length bias\" and \"lead bias.\"
Therefore, a \"wait and see\" approach is especially appropriate for
managing the very small, asymptomatic indeterminate renal mass in an
elderly patient. For a younger, healthy patient, the approach is
somewhat different: 1) US is used first to confirm if it is a simple,
benign cyst; 2) if US is not confirmatory, CT or MRI is used before and
after IV contrast to determine if it enhances; 3) if there is no
enhancement, nothing further need be done; 4) if it enhances, a early
surgical intervention or a follow-up approach may be performed; 5) if it
grows to 2 cm in diameter, it should be removed by kidney-sparing
surgery.

**Magnetic Resonance Imaging**

With the exception of angiomyolipomas and simple renal cysts, unenhanced
MRI cannot characterize renal masses. However, MRI using IV gadolinium
contrast agents now provides sensitivity and specificity similar to CT
in detecting contrast enhancement and identifying a mass requiring
surgery. Previously it was felt that MRI with gadolinium was
particularly applicable to patients with renal insufficiency for whom
conventional contrast would be significantly nephrotoxic. However, it
has been suggested recently that the development of nephrogenic systemic
fibrosis is associated with the administration of gadolinium in patients
with renal failure, and further studies are necessary to determine this
exact relationship. Gadolinium is still felt to be safe in patients with
a history of allergy to conventional contrast agents.

One group of researchers demonstrated that it is possible to calculate
percentage of enhancement of renal masses at MRI and that this can be
used to characterize renal masses. In another study, 73 patients with 93
renal masses underwent contrast-enhanced MRI, and quantitative
enhancement with signal intensity measurement analysis (percentage
enhancement) was compared to qualitative analysis of enhancement with
image subtraction to determine which was superior for detecting
malignancy. Sensitivity and specificity for diagnosing malignancy based
on enhancement were 95% and 53%, respectively, for quantitative analysis
and 99% and 58%, respectively, for qualitative analysis. Three of four
malignant lesions incorrectly assigned as benign by quantitative method
were hyperintense on unenhanced MRI. All were accurately diagnosed as
being malignant by qualitative method.

In a recent study, 69 cystic renal masses were evaluated using CT and
MRI within one year of each other, with consensus analysis by two
radiologists. Wall thickness, septal thickness, number of septa,
enhancement, and lesions were classified using the Bosniak
classification. There was CT and MRI agreement in 56 of 69 lesions (81%)
and disagreement in 13 of 69 lesions (19%). In 8 (12%) more septa were
seen, and in 7 (10%) increased wall and or septal thickness were seen on
MRI. In two lesions (3%) CT and MRI enhancement features were different.
Overall MRI upgraded seven lesions: from category II to IIF in two, from
IIF to III in three, and III to IV in two. CT and MRI were felt to be
similar in evaluation of most renal cystic mass lesions. However, MRI
may depict additional findings such as an increase in number of septa,
septal and/or wall thickness, and enhancement. Such findings would
result in MRI upgrading cystic lesions and thus may alter patient
management. The authors recommend caution in interpreting MRI of complex
cystic renal masses, and more specifically those that are borderline
between categories IIF and III without additional correlative imaging.

**Nuclear Medicine**

Radionuclide scintigraphy with a cortical imaging agent (e.g., DMSA) has
a limited role in evaluating of the indeterminate renal mass, being used
primarily to identify the so-called column of Bertin or junctional zone,
which may be causing a pseudotumor effect on IVP or US.
Fluorine-18-2-fluoro-2-deoxy-D-glucose positron emission tomography
(FDG-PET) may prove to be useful in detecting renal tumors and
characterizing indeterminate renal cysts. Although there were false
negatives in both the tumor group and the indeterminate cyst group,
there were no false positives. Others have reported varying accuracies
for detecting renal cell carcinoma, but in general the low sensitivity
of FDG-PET for renal cell carcinoma detection and characterization has
limited its use for this purpose.

**Angiography**

Although two-thirds of renal tumors have enough vascularity to allow
identification of tumor neovascularity, one-third will be of such a
hypovascular or \"avascular\" state that angiography will not help
identify the lesion as benign or malignant. This is even true of renal
carcinomas presenting with acute perirenal hemorrhage. For some
applications of nephron-sparing surgery for small renal neoplasms, the
urologic surgeon uses aortography or selective angiography to provide a
road map to assist in resection.

**Aspiration and Biopsy**

Biopsy of the indeterminate renal mass has a limited role in the current
era of high-quality imaging. In a survey by the Society of Uroradiology
reporting on approximately 16,000 cases, 92% of uroradiologists accepted
the US findings of a cyst as being sufficient for diagnosis and 100%
accepted the CT criteria of a simple or category II cyst as being
sufficiently diagnostic. If cyst aspiration is done, cytologic
evaluation is considered the laboratory study of choice. Although
aspiration of clear fluid usually indicates a benign cyst, clear fluid
was found in 19 cystic renal cell carcinomas, only 11 of which had
positive cytologic evaluation. Therefore, the gross and laboratory
analysis of aspirated fluid is not conclusive, and CT is considered the
\"gold standard\" in evaluating cystic masses. However, aspiration or
biopsy does have certain indications: confirmation of an infected cyst
or abscess, and identification of lymphoma or a metastasis in a kidney
where either diagnosis would affect clinical management.

In the last few years, in part due to the development of new techniques
in histological and molecular analysis, the indications for renal mass
biopsy have increased and now include the following: confirmation of
renal cell carcinoma when the surgical risk is high, when disease is
either locally advanced or metastatic; when masses have equivocal
imaging features; when a solid mass is present in a solitary or
transplant kidney; and prior to ablative therapies.

Initial laparoscopic evaluation of complex renal cysts may replace open
surgery in some cases. Laparoscopic biopsy of cystic renal cell
carcinoma followed by open surgery does not seem to increase incidence
of seeding or metastases.

**Summary**

CT is the modality of choice for evaluating indeterminate renal lesions
that are suspicious for malignancy. For those patients who cannot
tolerate iodinated IV contrast material due to allergy, MRI with
gadolinium contrast is advised. The newer techniques have shown that MRI
is also capable of characterizing indeterminate renal masses. When CT
and MRI are compared in the evaluation of cystic renal masses, MRI
appears to be more sensitive and tends to upgrade cystic lesions. Thus
caution is advised when using MRI findings to direct clinical management
at this time. Radionuclide scintigraphy has a role limited to confirming
normal renal tissue. Angiography is used primarily to define vascular
anatomy before nephron-sparing surgery. Renal aspiration or biopsy has
few indications: confirming an infected cyst or identifying lymphoma or
a metastasis as the cause of the indeterminate renal mass.

**Anticipated Exceptions**

Nephrogenic systemic fibrosis (NSF, also known as nephrogenic fibrosing
dermopathy) was first identified in 1997 and has recently generated
substantial concern among radiologists, referring doctors and lay
people. Until the last few years, gadolinium-based MR contrast agents
were widely believed to be almost universally well tolerated, extremely
safe and non-nephrotoxic, even when used in patients with impaired renal
function. All available experience suggests that these agents remain
generally very safe, but recently some patients with renal failure who
have been exposed to gadolinium contrast agents (the percentage is
unclear) have developed NSF, a syndrome that can be fatal. Further
studies are necessary to determine what the exact relationships are
between gadolinium-containing contrast agents, their specific components
and stoichiometry, patient renal function and NSF. Current theory links
the development of NSF to the administration of relatively high doses
(e.g., \>0.2 mM/kg) and to agents in which the gadolinium is least
strongly chelated. The FDA has recently issued a \"black box\" warning
concerning these contrast agents
(<http://www.fda.gov/cder/drug/InfoSheets/HCP/gcca_200705HCP.pdf>).

This warning recommends that, until further information is available,
gadolinium contrast agents should not be administered to patients with
either acute or significant chronic kidney disease (estimated GFR \<30
mL/min/1.73m^2^), recent liver or kidney transplant or hepato-renal
syndrome, unless a risk-benefit assessment suggests that the benefit of
administration in the particular patient clearly outweighs the potential
risk(s).

**Abbreviations**

-   CT, computed tomography

-   DMSA, dimercaptosuccinic acid

-   INV, invasive

-   IP, in progress

-   MRI, magnetic resonance imaging

-   NUC, nuclear medicine

-   US, ultrasound

#### CLINICAL ALGORITHM(S)

None available

### EVIDENCE SUPPORTING THE RECOMMENDATIONS

#### TYPE OF EVIDENCE SUPPORTING THE RECOMMENDATIONS

The recommendations are based on analysis of the current literature and
expert panel consensus.

### BENEFITS/HARMS OF IMPLEMENTING THE GUIDELINE RECOMMENDATIONS

#### POTENTIAL BENEFITS

Selection of appropriate radiologic imaging procedures for evaluation of
patients with an indeterminate renal mass

#### POTENTIAL HARMS

-   Ultrasound (US) can be falsely negative with avascular tumor masses
    and falsely positive with inflammatory masses.

-   The relative radiation level is high for computed tomography (CT) of
    the kidney without and with contrast; medium with (CT) of the kidney
    without contrast; and low with nuclear imaging (NUC) scan with
    dimercaptosuccinic acid (DMSA) of the kidney and X-ray intravenous
    urography.

-   It has been suggested recently that the development of nephrogenic
    systemic fibrosis is associated with the administration of
    gadolinium in patients with renal failure, and further studies are
    necessary to determine this exact relationship. Until further
    information is available, gadolinium contrast agents should not be
    administered to patients with either acute or significant chronic
    kidney disease (estimated GFR \<30 mL/min/1.73m^2^), recent liver or
    kidney transplant or hepato-renal syndrome, unless a risk-benefit
    assessment suggests that the benefit of administration in the
    particular patient clearly outweighs the potential risk(s).

### QUALIFYING STATEMENTS

#### QUALIFYING STATEMENTS

An American College of Radiology (ACR) Committee on Appropriateness
Criteria and its expert panels have developed criteria for determining
appropriate imaging examinations for diagnosis and treatment of
specified medical condition(s). These criteria are intended to guide
radiologist, radiation oncologist, and referring physicians in making
decisions regarding radiologic imaging and treatment. Generally, the
complexity and severity of a patient\'s clinical condition should
dictate the selection of appropriate imaging procedures or treatments.
Only those exams generally used for evaluation of the patient\'s
condition are ranked. Other imaging studies necessary to evaluate other
co-existent diseases or other medical consequences of this condition are
not considered in this document. The availability of equipment or
personnel may influence the selection of appropriate imaging procedures
or treatments. Imaging techniques classified as investigational by the
U.S. Food and Drug Administration (FDA) have not been considered in
developing these criteria; however, study of new equipment and
applications should be encouraged. The ultimate decision regarding the
appropriateness of any specific radiologic examination or treatment must
be made by the referring physician and radiologist in light of all the
circumstances presented in an individual examination.

### IMPLEMENTATION OF THE GUIDELINE

#### DESCRIPTION OF IMPLEMENTATION STRATEGY

An implementation strategy was not provided.

#### IMPLEMENTATION TOOLS

Personal Digital Assistant (PDA) Downloads

For information about
[availability](#identifying-information-and-availability), see the
\"Availability of Companion Documents\" and \"Patient Resources\" fields
below.

### INSTITUTE OF MEDICINE (IOM) NATIONAL HEALTHCARE QUALITY REPORT CATEGORIES

#### IOM CARE NEED

Getting Better

#### IOM DOMAIN

Effectiveness

### IDENTIFYING INFORMATION AND AVAILABILITY

#### BIBLIOGRAPHIC SOURCE(S)

Israel GM, Francis IR, Baumgarten DA, Bluth EI, Bush WH Jr., Casalino
DD, Curry NS, Jafri SZ, Kawashima A, Papanicolaou N, Remer EM, Sandler
CM, Spring DB, Fulgham P, Expert Panel on Urologic Imaging.
Indeterminate renal mass. \[online publication\]. Reston (VA): American
College of Radiology (ACR); 2007. 7 p. \[65 references\]

#### ADAPTATION

Not applicable: The guideline was not adapted from another source.

#### DATE RELEASED

1996 (revised 2007)

#### GUIDELINE DEVELOPER(S)

American College of Radiology - Medical Specialty Society

#### SOURCE(S) OF FUNDING

American College of Radiology (ACR) provided the funding and the
resources for these ACR Appropriateness Criteria®.

#### GUIDELINE COMMITTEE

Committee on Appropriateness Criteria; Expert Panel on Urologic Imaging

#### COMPOSITION OF GROUP THAT AUTHORED THE GUIDELINE

*Panel Members*: Gary M. Israel, MD; Isaac R. Francis, MD; Deborah A.
Baumgarten, MD; Edward I. Bluth, MD; William H. Bush, Jr., MD; David D.
Casalino, MD; Nancy S. Curry, MD; S. Zafar H. Jafri, MD; Akira
Kawashima, MD; Nicholas Papanicolaou, MD1; Erick M. Remer, MD1; Carl M.
Sandler, MD; David B. Spring, MD;Pat Fulgham, MD

#### FINANCIAL DISCLOSURES/CONFLICTS OF INTEREST

Not stated

#### GUIDELINE STATUS

This is the current release of the guideline.

This guideline updates a previous version Francis IR, Choyke PL, Bluth
E, Bush WH Jr, Casalino DD, Jafri SZ, Kawashima A, Kronthal A, Older RA,
Papanicolaou N, Ramchandani P, Rosenfield AT, Sandler C, Segal AJ,
Tempany C, Resnick MI, Expert Panel on Urologic Imaging. Indeterminate
renal masses. \[online publication\]. Reston (VA): American College of
Radiology (ACR); 2005. 7 p. \[54 references\]

The appropriateness criteria are reviewed annually and updated by the
panels as needed, depending on introduction of new and highly
significant scientific evidence.

#### GUIDELINE AVAILABILITY

Electronic copies: Available in Portable Document Format (PDF) from the
[American College of Radiology (ACR) Web
site](http://www.acr.org/SecondaryMainMenuCategories/quality_safety/app_criteria/pdf/ExpertPanelonUrologicImaging/IndeterminateRenalMassesDoc8.aspx).

ACR Appropriateness Criteria® *Anytime*, *Anywhere*™ (PDA application).
Available from the [ACR Web
site](http://www.acr.org/SecondaryMainMenuCategories/ACRStore/FeaturedCategories/QualityandSafety/ac_pda.aspx).

Print copies: Available from the American College of Radiology, 1891
Preston White Drive, Reston, VA 20191. Telephone: (703) 648-8900.

#### AVAILABILITY OF COMPANION DOCUMENTS

The following are available:

-   ACR Appropriateness Criteria®. Background and development. Reston
    (VA): American College of Radiology; 2 p. Electronic copies:
    Available in Portable Document Format (PDF) from the [American
    College of Radiology (ACR) Web
    site](http://www.acr.org/SecondaryMainMenuCategories/quality_safety/app_criteria.aspx).

-   ACR Appropriateness Criteria®. Relative radiation level information.
    Reston (VA): American College of Radiology; 2 p. Electronic copies:
    Available in Portable Document Format (PDF) from the [American
    College of Radiology (ACR) Web
    site](http://www.acr.org/SecondaryMainMenuCategories/quality_safety/app_criteria/RRLInformation.aspx).

#### PATIENT RESOURCES

None available

#### NGC STATUS

This NGC summary was completed by ECRI on March 7, 2006. This summary
was updated by ECRI Institute on May 17, 2007 following the U.S. Food
and Drug Administration (FDA) advisory on Gadolinium-based contrast
agents. This summary was updated by ECRI Institute on June 20, 2007
following the U.S. Food and Drug Administration (FDA) advisory on
gadolinium-based contrast agents. This NGC summary was updated by ECRI
Institute on November 21, 2007.

#### COPYRIGHT STATEMENT

Instructions for downloading, use, and reproduction of the American
College of Radiology (ACR) Appropriateness Criteria® may be found on the
[ACR Web
site](http://www.acr.org/SecondaryMainMenuCategories/quality_safety/app_criteria/ACRAppropriatenessCriteriaTermsandConditionsDoc1.aspx).

### DISCLAIMER

#### NGC DISCLAIMER

The National Guideline Clearinghouse™ (NGC) does not develop, produce,
approve, or endorse the guidelines represented on this site.

All guidelines summarized by NGC and hosted on our site are produced
under the auspices of medical specialty societies, relevant professional
associations, public or private organizations, other government
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Guidelines represented on the NGC Web site are submitted by guideline
developers, and are screened solely to determine that they meet the NGC
Inclusion Criteria which may be found at
<http://www.guideline.gov/about/inclusion.aspx> .

NGC, AHRQ, and its contractor ECRI Institute make no warranties
concerning the content or clinical efficacy or effectiveness of the
clinical practice guidelines and related materials represented on this
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Readers with questions regarding guideline content are directed to
contact the guideline developer.

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© 1998-2008 National Guideline Clearinghouse

Date Modified: 11/3/2008