Editing Incidental imaging finding

{{Short description|Unanticipated finding unrelated to the original inquiry}}
{{Use dmy dates|date=June 2020}}
In [[medicine|medical or research imaging]], an '''incidental imaging finding''' (also called an '''incidentaloma''') is an unanticipated finding which is not related to the original diagnostic inquiry. As with other types of [[incidental medical findings]], they may represent a diagnostic, ethical, and philosophical dilemma because their significance is unclear. While some coincidental findings may lead to beneficial diagnoses, others may lead to [[overdiagnosis]] that results in unnecessary testing and treatment, sometimes called the "cascade effect".<ref>{{Cite journal|last1=Lumbreras|first1=B|last2=Donat|first2=L|last3=Hernández-Aguado|first3=I|date=2010-04-01|title=Incidental findings in imaging diagnostic tests: a systematic review|journal=The British Journal of Radiology|volume=83|issue=988|pages=276–289|doi=10.1259/bjr/98067945|pmid=20335439|issn=0007-1285|pmc=3473456}}</ref>

Incidental findings are common in imaging. For instance, around 1 in every 3 cardiac [[MRI]]s result in an incidental finding.<ref name="O'Sullivan2018">{{cite journal |last1=O'Sullivan |first1=JW |last2=Muntinga |first2=T |last3=Grigg |first3=S |last4=Ioannidis |first4=JPA |title=Prevalence and outcomes of incidental imaging findings: Umbrella review |journal=[[The BMJ|BMJ]] |date=18 June 2018 |volume=361 |pages=k2387 |doi=10.1136/bmj.k2387 |pmid=29914908|pmc=6283350 }}</ref> Incidence is similar for chest [[CT scan]]s (~30%).<ref name="O'Sullivan2018"/>

As the use of medical imaging increases, the number of incidental findings also increases.{{citation needed|date=May 2022}}

== Adrenal ==
Incidental adrenal masses on imaging are common (0.6 to 1.3% of all abdominal CT). Differential diagnosis include [[adrenal adenoma|adenoma]], [[myelolipoma]], cyst, [[lipoma]], [[pheochromocytoma]], [[adrenal cancer]], [[metastatic cancer]], [[hyperplasia]], and [[tuberculosis]].<ref name="pmid9429862">{{cite journal |author=Cook DM |title=Adrenal mass |journal=Endocrinol. Metab. Clin. North Am. |volume=26 |issue=4 |pages=829–52 | date=December 1997 |pmid=9429862 |doi= 10.1016/s0889-8529(05)70284-x}}</ref>  Some of these lesions are easily identified by radiographic appearance; however, it is often adenoma vs. cancer/metastasis that is most difficult to distinguish.  Thus, clinical guidelines have been developed to aid in diagnosis and decision-making.<ref name="urlwww.aace.com">{{Cite web|url=https://www.aace.com/files/adrenal-guidelines.pdf|title=2009 AACE/AAES Guidelines, Adrenal incidentaloma|access-date=17 September 2014|archive-date=29 August 2017|archive-url=https://web.archive.org/web/20170829230949/https://www.aace.com/files/adrenal-guidelines.pdf|url-status=dead}}</ref> Although adrenal incidentalomas are common, they are not commonly cancerous - less than 1% of all adrenal incidentalomas are malignant.<ref name="O'Sullivan2018"/>

The first considerations are size and radiographic appearance of the mass.  Suspicious adrenal masses or those ≥4&nbsp;cm are recommended for complete removal by adrenalectomy.  Masses <4&nbsp;cm may also be recommended for removal if they are found to be hormonally active, but are otherwise recommended for observation.<ref name="pmid12614096">{{cite journal  |vauthors=Grumbach MM, Biller BM, Braunstein GD, etal |title=Management of the clinically inapparent adrenal mass ("incidentaloma") |journal=Ann. Intern. Med. |volume=138 |issue=5 |pages=424–9 |year=2003 |pmid=12614096 |doi=10.7326/0003-4819-138-5-200303040-00013|s2cid=23454526 }}</ref>  All adrenal masses should receive hormonal evaluation. Hormonal evaluation includes:<ref name="pmid17287480">{{cite journal |author=Young WF |title=Clinical practice. The incidentally discovered adrenal mass |journal=N. Engl. J. Med. |volume=356 |issue=6 |pages=601–10 |year=2007 |pmid=17287480 |doi=10.1056/NEJMcp065470}}</ref>
* 1-mg overnight [[dexamethasone suppression test]]
* 24-hour urinary specimen for measurement of fractionated [[metanephrines]] and [[catecholamines]]
* [[Blood plasma]] [[aldosterone]] concentration and plasma [[renin]] activity, ''if hypertension is present''
On CT scan, benign [[adenoma]]s typically are of low [[radiodensity]] (due to fat content). A radiodensity equal to or below 10 [[Hounsfield units]] (HU) is considered diagnostic of an adenoma.<ref>{{cite web|url=http://www.radiologyassistant.nl/en/p421aee7c659fc/adrenals.html|archive-url=https://web.archive.org/web/20130307065115/http://www.radiologyassistant.nl/en/p421aee7c659fc/adrenals.html|url-status=dead|archive-date=7 March 2013|title=Adrenals - Differentiating benign from malignant|author=Theo Falke and Robin Smithuis|website=Radiology Assistant|access-date=2018-01-02}}</ref> An adenoma also shows rapid [[radiocontrast washout]] (50% or more of the contrast medium washes out at 10 minutes). If the hormonal evaluation is negative and imaging suggests benign lesion, follow up may be considered. Imaging at 6, 12, and 24 months and repeat hormonal evaluation yearly for 4 years is often recommended,<ref name="pmid17287480"/> but there exists controversy about harm/benefit of such screening as there is a high subsequent false-positive rate (about 50:1) and overall low incidence of adrenal carcinoma.<ref name="pmid19439510">{{cite journal |vauthors=Cawood TJ, Hunt PJ, O'Shea D, Cole D, Soule S |title=Recommended evaluation of adrenal incidentalomas is costly, has high false-positive rates and confers a risk of fatal cancer that is similar to the risk of the adrenal lesion becoming malignant; time for a rethink? |journal=Eur. J. Endocrinol. |volume=161 |issue=4 |pages=513–27 | date=October 2009 |pmid=19439510 |doi=10.1530/EJE-09-0234 |doi-access=free }}</ref>

== Brain ==
[[Autopsy]] series have suggested that [[pituitary gland|pituitary]] incidentalomas may be quite common. It has been estimated that perhaps 10% of the adult population may harbor such [[endocrinology|endocrinologically]] inert lesions.<ref name="pmid8154641">{{cite journal|year=1994|title=Pituitary magnetic resonance imaging in normal human volunteers: occult adenomas in the general population|journal=Ann. Intern. Med.|volume=120|issue=10|pages=817–20|doi=10.7326/0003-4819-120-10-199405150-00001|pmid=8154641|vauthors=Hall WA, Luciano MG, Doppman JL, Patronas NJ, Oldfield EH|s2cid=23833253}}</ref> Most of these lesions, especially those which are small, will not grow. However, some form of long-term surveillance has been recommended based on the size and presentation of the lesion.<ref name="pmid9429857">{{cite journal|author=Molitch ME|year=1997|title=Pituitary incidentalomas|journal=Endocrinol. Metab. Clin. North Am.|volume=26|issue=4|pages=725–40|doi=10.1016/S0889-8529(05)70279-6|pmid=9429857}}</ref> With pituitary adenomas larger than 1&nbsp;cm, a baseline pituitary hormonal function test should be done, including measurements of serum levels of [[Thyroid-stimulating hormone|TSH]], [[prolactin]], [[IGF-1]] (as a test of [[growth hormone]] activity), adrenal function (i.e. 24 hour urine cortisol, dexamethasone suppression test), [[testosterone]] in men, and [[estradiol]] in [[amenorrhea|amenorrheic]] women.<ref>{{cite journal|author=Snyder|year=2021|title=Causes, presentation, and evaluation of sellar masses|url=https://www.uptodate.com/contents/causes-presentation-and-evaluation-of-sellar-masses|url-access=subscription}}</ref>

== Thyroid and parathyroid ==
Incidental [[thyroid]] masses may be found in 9% of patients undergoing bilateral carotid duplex ultrasonography.<ref name="pmid16230549">{{cite journal|year=2005|title=The significance of incidental thyroid abnormalities identified during carotid duplex ultrasonography|journal=Archives of Surgery|volume=140|issue=10|pages=981–5|doi=10.1001/archsurg.140.10.981|pmid=16230549|vauthors=Steele SR, Martin MJ, Mullenix PS, Azarow KS, Andersen CA|doi-access=}}</ref>

Some experts<ref name="pmid15941700">{{cite journal|year=2005|title=Continuing controversies in the management of thyroid nodules|journal=Ann. Intern. Med.|volume=142|issue=11|pages=926–31|doi=10.7326/0003-4819-142-11-200506070-00011|pmid=15941700|vauthors=Castro MR, Gharib H|s2cid=41308483}}</ref> recommend that nodules > 1&nbsp;cm (unless the [[Thyroid-stimulating hormone|TSH]] is suppressed) or those with ultrasonographic features of malignancy should be biopsied by [[Needle aspiration biopsy|fine needle aspiration]]. [[Computed tomography]]  is inferior to [[ultrasound]] for evaluating thyroid nodules.<ref name="pmid17056928">{{cite journal|year=2006|title=Significance of incidental thyroid lesions detected on CT: correlation among CT, sonography, and pathology|journal=AJR. American Journal of Roentgenology|volume=187|issue=5|pages=1349–56|doi=10.2214/AJR.05.0468|pmid=17056928|vauthors=Shetty SK, Maher MM, Hahn PF, Halpern EF, Aquino SL}}</ref> Ultrasonographic markers of malignancy are:<ref name="pmid11994321">{{cite journal|year=2002|title=Risk of malignancy in nonpalpable thyroid nodules: predictive value of ultrasound and color-Doppler features|journal=J. Clin. Endocrinol. Metab.|volume=87|issue=5|pages=1941–6|doi=10.1210/jcem.87.5.8504|pmid=11994321|vauthors=Papini E, Guglielmi R, Bianchini A, etal|doi-access=free}}</ref>
* solid hypoechoic appearance
* irregular or blurred margins
* intranodular vascular spots or pattern
* microcalcifications

Incidental [[parathyroid]] masses may be found in 0.1% of patients undergoing bilateral carotid duplex ultrasonography.<ref name="pmid16230549" />

[[The American College of Radiology]] recommends the following workup for thyroid nodules as incidental imaging findings on [[CT scan|CT]], [[Magnetic resonance imaging|MRI]] or [[PET-CT]]:<ref>{{cite web|url=https://radiopaedia.org/blog/reporting-of-incidental-thyroid-nodules-on-ct-and-mri-1|title=Reporting of incidental thyroid nodules on CT and MRI|author=Jenny Hoang|date=2013-11-05|website=[[Radiopaedia]]}}, citing:
* {{cite journal|last1=Hoang|first1=Jenny K.|last2=Langer|first2=Jill E.|last3=Middleton|first3=William D.|last4=Wu|first4=Carol C.|last5=Hammers|first5=Lynwood W.|last6=Cronan|first6=John J.|last7=Tessler|first7=Franklin N.|last8=Grant|first8=Edward G.|last9=Berland|first9=Lincoln L.|title=Managing Incidental Thyroid Nodules Detected on Imaging: White Paper of the ACR Incidental Thyroid Findings Committee|journal=Journal of the American College of Radiology|volume=12|issue=2|year=2015|pages=143–150|issn=1546-1440|doi=10.1016/j.jacr.2014.09.038|pmid=25456025}}</ref>
{|class="wikitable"
! Features !! Workup
|-
|
* High [[Positron emission tomography|PET]] signal or
* Local invasiveness or
* Suspicious lymph nodes
| Very likely ultrasonography
|-
| Multiple nodules
| Likely ultrasonography
|-
| Solitary nodule in person younger than 35 years old
|
* Likely ultrasonography if at least 1&nbsp;cm large in adults, or for any size in children.
* None needed if less than 1&nbsp;cm in adults
|-
| Solitary nodule in person at least 35 years old
|
* Likely ultrasonography if at least 1.5&nbsp;cm large
* None needed if less than 1.5&nbsp;cm
|}

== Pulmonary ==
Studies of whole body screening [[computed tomography]] find abnormalities in the lungs of 14% of patients.<ref name="pmid16170016">{{cite journal|year=2005|title=Whole-body CT screening: spectrum of findings and recommendations in 1192 patients|journal=Radiology|volume=237|issue=2|pages=385–94|doi=10.1148/radiol.2372041741|pmid=16170016|vauthors=Furtado CD, Aguirre DA, Sirlin CB, etal}}</ref> [[Clinical practice guideline]]s by the [[American College of Chest Physicians]] advise on the evaluation of the [[solitary pulmonary nodule]].<ref name="pmid17873164">{{cite journal|year=2007|title=Evaluation of Patients With Pulmonary Nodules: When Is It Lung Cancer?: ACCP Evidence-Based Clinical Practice Guidelines (2nd Edition)|journal=Chest|volume=132|issue=3_suppl|pages=108S–130S|doi=10.1378/chest.07-1353|pmid=17873164|vauthors=Gould MK, Fletcher J, Iannettoni MD, etal}}</ref>

== Kidney ==
[[File:Contrast-enhanced ultrasonography of benign lesion.jpg|thumb|Unspecific cortical lesion on [[CT scan]] is confirmed cystic and benign with [[contrast-enhanced ultrasound|contrast-enhanced]] [[renal ultrasonography]].]]
Most [[renal cell carcinoma]]s are now found incidentally.<ref name="pmid11343669">{{cite journal |vauthors=Reddan DN, Raj GV, Polascik TJ |title=Management of small renal tumors: an overview |journal=Am. J. Med. |volume=110 |issue=7 |pages=558–62 |year=2001 |pmid=11343669 |doi=10.1016/S0002-9343(01)00650-7 }}</ref> Tumors less than 3&nbsp;cm in diameter less frequently have aggressive [[histology]].<ref name="pmid16890647">{{cite journal  |vauthors=Remzi M, Ozsoy M, Klingler HC, etal |title=Are small renal tumors harmless? Analysis of histopathological features according to tumors 4 cm or less in diameter |journal=J. Urol. |volume=176 |issue=3 |pages=896–9 |year=2006 |pmid=16890647 |doi=10.1016/j.juro.2006.04.047}}</ref>

A [[CT scan]] is the first choice modality for workup of solid masses in the kidneys. Nevertheless, hemorrhagic cysts can resemble renal cell carcinomas on CT, but they are easily distinguished with [[Doppler ultrasonography]] (Doppler US). In renal cell carcinomas, Doppler US often shows vessels with high velocities caused by neovascularization and arteriovenous shunting. Some renal cell carcinomas are hypovascular and not distinguishable with Doppler US. Therefore, renal tumors without a Doppler signal, which are not obvious simple cysts on US and CT, should be further investigated with [[contrast-enhanced ultrasound]], as this is more sensitive than both Doppler US and CT for the detection of hypovascular tumors.<ref name=Hansen2015>Content initially copied from: {{cite journal|last1=Hansen|first1=Kristoffer|last2=Nielsen|first2=Michael|last3=Ewertsen|first3=Caroline|title=Ultrasonography of the Kidney: A Pictorial Review|journal=Diagnostics|volume=6|issue=1|year=2015|pages=2|issn=2075-4418|doi=10.3390/diagnostics6010002|pmid=26838799|pmc=4808817|doi-access=free}} [https://creativecommons.org/licenses/by/4.0/ (CC-BY 4.0)]</ref>

== Spinal ==
The increasing use of MRI, often during diagnostic work-up for back or lower extremity pain, has led to a significant increase in the number of incidental findings that are most often clinically inconsequential.  The most common include:<ref name="pmid21512084">{{cite journal  |vauthors=Park HJ, Jeon YH, Rho MH, etal |title=Incidental findings of the lumbar spine at MRI during herniated intervertebral disk disease evaluation |journal=AJR Am J Roentgenol |volume=196 |issue=5 |pages=1151–5 | date=May 2011 |pmid=21512084 |doi=10.2214/AJR.10.5457 }}</ref>
* [[vertebral hemangioma]]
* fibrolipoma (a [[lipoma]] with fibrous areas)
* [[Tarlov cyst]]

Sometimes normally asymptomatic findings can present with symptoms and these cases when identified cannot then be considered as incidentalomas.{{citation needed|date=August 2020}}

== Criticism ==
The concept of the "incidentaloma" has been criticized, as such lesions do not have much in common other than the history of an incidental identification and the assumption that they are clinically inert. It has been proposed just to say that such lesions have been "incidentally found."<ref name="pmid12455801">{{cite journal |vauthors=Mirilas P, Skandalakis JE |title=Benign anatomical mistakes: incidentaloma |journal=The American Surgeon |volume=68 |issue=11 |pages=1026–8 |year=2002 |doi=10.1177/000313480206801119 |pmid=12455801 }}</ref> The underlying pathology shows no unifying histological concept.{{citation needed|date=May 2022}}

==References==
{{Reflist}}

{{Unnecessary health care}}
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[[Category:Endocrine diseases]]
[[Category:Diagnostic medical imaging]]
[[Category:Oncology]]
[[Category:Radiology]]
[[Category:Unnecessary health care]]