Incidental imaging finding

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In 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". [1]

Contents

Incidental findings are common in imaging. For instance, around 1 in every 3 cardiac MRIs result in an incidental finding. [2] Incidence is similar for chest CT scans (~30%). [2]

As the use of medical imaging increases, the number of incidental findings also increases.[ citation needed ]

Adrenal

Incidental adrenal masses on imaging are common (0.6 to 1.3% of all abdominal CT). Differential diagnosis include adenoma, myelolipoma, cyst, lipoma, pheochromocytoma, adrenal cancer, metastatic cancer, hyperplasia, and tuberculosis. [3] 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. [4] Although adrenal incidentalomas are common, they are not commonly cancerous - less than 1% of all adrenal incidentalomas are malignant. [2]

The first considerations are size and radiographic appearance of the mass. Suspicious adrenal masses or those ≥4 cm are recommended for complete removal by adrenalectomy. Masses <4 cm may also be recommended for removal if they are found to be hormonally active, but are otherwise recommended for observation. [5] All adrenal masses should receive hormonal evaluation. Hormonal evaluation includes: [6]

On CT scan, benign adenomas 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. [7] 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, [6] 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. [8]

Brain

Autopsy series have suggested that pituitary incidentalomas may be quite common. It has been estimated that perhaps 10% of the adult population may harbor such endocrinologically inert lesions. [9] 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. [10] With pituitary adenomas larger than 1 cm, a baseline pituitary hormonal function test should be done, including measurements of serum levels of 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 amenorrheic women. [11]

Thyroid and parathyroid

Incidental thyroid masses may be found in 9% of patients undergoing bilateral carotid duplex ultrasonography. [12]

Some experts [13] recommend that nodules > 1 cm (unless the TSH is suppressed) or those with ultrasonographic features of malignancy should be biopsied by fine needle aspiration. Computed tomography is inferior to ultrasound for evaluating thyroid nodules. [14] Ultrasonographic markers of malignancy are: [15]

Incidental parathyroid masses may be found in 0.1% of patients undergoing bilateral carotid duplex ultrasonography. [12]

The American College of Radiology recommends the following workup for thyroid nodules as incidental imaging findings on CT, MRI or PET-CT: [16]

FeaturesWorkup
  • High PET signal or
  • Local invasiveness or
  • Suspicious lymph nodes
Very likely ultrasonography
Multiple nodulesLikely ultrasonography
Solitary nodule in person younger than 35 years old
  • Likely ultrasonography if at least 1 cm large in adults, or for any size in children.
  • None needed if less than 1 cm in adults
Solitary nodule in person at least 35 years old
  • Likely ultrasonography if at least 1.5 cm large
  • None needed if less than 1.5 cm

Pulmonary

Studies of whole body screening computed tomography find abnormalities in the lungs of 14% of patients. [17] Clinical practice guidelines by the American College of Chest Physicians advise on the evaluation of the solitary pulmonary nodule. [18]

Kidney

Unspecific cortical lesion on CT scan is confirmed cystic and benign with contrast-enhanced renal ultrasonography. Contrast-enhanced ultrasonography of benign lesion.jpg
Unspecific cortical lesion on CT scan is confirmed cystic and benign with contrast-enhanced renal ultrasonography.

Most renal cell carcinomas are now found incidentally. [19] Tumors less than 3 cm in diameter less frequently have aggressive histology. [20]

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. [21]

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: [22]

Sometimes normally asymptomatic findings can present with symptoms and these cases when identified cannot then be considered as incidentalomas.[ citation needed ]

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." [23] The underlying pathology shows no unifying histological concept.[ citation needed ]

Related Research Articles

Liver tumors are abnormal growth of liver cells on or in the liver. Several distinct types of tumors can develop in the liver because the liver is made up of various cell types. Liver tumors can be classified as benign (non-cancerous) or malignant (cancerous) growths. They may be discovered on medical imaging, and the diagnosis is often confirmed with liver biopsy. Signs and symptoms of liver masses vary from being asymptomatic to patients presenting with an abdominal mass, hepatomegaly, abdominal pain, jaundice, or some other liver dysfunction. Treatment varies and is highly specific to the type of liver tumor.

<span class="mw-page-title-main">Adenoma</span> Benign tumor of glandular origin and/or characteristics

An adenoma is a benign tumor of epithelial tissue with glandular origin, glandular characteristics, or both. Adenomas can grow from many glandular organs, including the adrenal glands, pituitary gland, thyroid, prostate, and others. Some adenomas grow from epithelial tissue in nonglandular areas but express glandular tissue structure. Although adenomas are benign, they should be treated as pre-cancerous. Over time adenomas may transform to become malignant, at which point they are called adenocarcinomas. Most adenomas do not transform. However, even though benign, they have the potential to cause serious health complications by compressing other structures and by producing large amounts of hormones in an unregulated, non-feedback-dependent manner. Some adenomas are too small to be seen macroscopically but can still cause clinical symptoms.

<span class="mw-page-title-main">Pituitary adenoma</span> Tumor of the pituitary gland

Pituitary adenomas are tumors that occur in the pituitary gland. Most pituitary tumors are benign, approximately 35% are invasive and just 0.1% to 0.2% are carcinomas. Pituitary adenomas represent from 10% to 25% of all intracranial neoplasms, with an estimated prevalence rate in the general population of approximately 17%.

<span class="mw-page-title-main">Adrenocortical carcinoma</span> Cancer of the adrenal cortex

Adrenocortical carcinoma (ACC) is an aggressive cancer originating in the cortex of the adrenal gland.

<span class="mw-page-title-main">Benign tumor</span> Mass of cells which cannot spread throughout the body

A benign tumor is a mass of cells (tumor) that does not invade neighboring tissue or metastasize. Compared to malignant (cancerous) tumors, benign tumors generally have a slower growth rate. Benign tumors have relatively well differentiated cells. They are often surrounded by an outer surface or stay contained within the epithelium. Common examples of benign tumors include moles and uterine fibroids.

<span class="mw-page-title-main">Pleomorphic adenoma</span> Medical condition

Pleomorphic adenoma is a common benign salivary gland neoplasm characterised by neoplastic proliferation of epithelial (ductal) cells along with myoepithelial components, having a malignant potentiality. It is the most common type of salivary gland tumor and the most common tumor of the parotid gland. It derives its name from the architectural Pleomorphism seen by light microscopy. It is also known as "Mixed tumor, salivary gland type", which refers to its dual origin from epithelial and myoepithelial elements as opposed to its pleomorphic appearance.

<span class="mw-page-title-main">Hürthle cell neoplasm</span> Medical condition

Hürthle cell neoplasm is a rare tumor of the thyroid, typically seen in women between the ages of 70 and 80 years old. When benign, it is called a Hürthle cell adenoma, and when malignant it is called a Hürthle cell carcinoma. Hürthle cell adenoma is characterized by a mass of benign Hürthle cells. Typically such a mass is removed because it is not easy to predict whether it will transform into the malignant counterpart of Hürthle cell carcinoma, which is a subtype of follicular thyroid cancer.

<span class="mw-page-title-main">Adrenalectomy</span> Surgical removal of adrenal glands

Adrenalectomy is the surgical removal of one or both adrenal glands. It is usually done to remove tumors of the adrenal glands that are producing excess hormones or is large in size. Adrenalectomy can also be done to remove a cancerous tumor of the adrenal glands, or cancer that has spread from another location, such as the kidney or lung. Adrenalectomy is not performed on those who have severe coagulopathy or whose heart and lungs are too weak to undergo surgery. The procedure can be performed using an open incision (laparotomy) or minimally invasive laparoscopic or robot-assisted techniques. Minimally invasive techniques are increasingly the gold standard of care due to shorter length of stay in the hospital, lower blood loss, and similar complication rates.

Pituitary apoplexy is bleeding into or impaired blood supply of the pituitary gland. This usually occurs in the presence of a tumor of the pituitary, although in 80% of cases this has not been diagnosed previously. The most common initial symptom is a sudden headache, often associated with a rapidly worsening visual field defect or double vision caused by compression of nerves surrounding the gland. This is often followed by acute symptoms caused by lack of secretion of essential hormones, predominantly adrenal insufficiency.

<span class="mw-page-title-main">Incidental medical findings</span> Undiagnosed medical or psychiatric conditions discovered unintentionally during evaluation

Incidental medical findings are previously undiagnosed medical or psychiatric conditions that are discovered unintentionally and during evaluation for a medical or psychiatric condition. Such findings may occur in a variety of settings, including routine medical care, during biomedical research, during post-mortem autopsy, or during genetic testing.

<span class="mw-page-title-main">Adrenal tumor</span> Tumors of the adrenal gland, usually resulting in hormone overproduction

An adrenal tumor or adrenal mass is any benign or malignant neoplasms of the adrenal gland, several of which are notable for their tendency to overproduce endocrine hormones. Adrenal cancer is the presence of malignant adrenal tumors, and includes neuroblastoma, adrenocortical carcinoma and some adrenal pheochromocytomas. Most adrenal pheochromocytomas and all adrenocortical adenomas are benign tumors, which do not metastasize or invade nearby tissues, but may cause significant health problems by unbalancing hormones.

<span class="mw-page-title-main">Adrenocortical adenoma</span> Benign tumor of the adrenal gland

An adrenocortical adenoma or adrenal adenoma is commonly described as a benign neoplasm emerging from the cells that comprise the adrenal cortex. Like most adenomas, the adrenocortical adenoma is considered a benign tumor since the majority of them are non-functioning and asymptomatic. Adrenocortical adenomas are classified as ACTH-independent disorders, and are commonly associated with conditions linked to hyperadrenalism such as Cushing's syndrome (hypercortisolism) or Conn's syndrome (hyperaldosteronism), which is also known as primary aldosteronism. In addition, recent case reports further support the affiliation of adrenocortical adenomas with hyperandrogenism or florid hyperandrogenism which can cause hyperandrogenic hirsutism in females. "Cushing's syndrome" differs from the "Cushing's disease" even though both conditions are induced by hypercortisolism. The term "Cushing's disease" refers specifically to "secondary hypercortisolism" classified as "ACTH-dependent Cushing's syndrome" caused by pituitary adenomas. In contrast, "Cushing's syndrome" refers specifically to "primary hypercortisolism" classified as "ACTH-independent Cushing's syndrome" caused by adrenocortical adenomas.

<span class="mw-page-title-main">Thyroid adenoma</span> Benign tumor of the thyroid gland

A thyroid adenoma is a benign tumor of the thyroid gland, that may be inactive or active as a toxic adenoma.

<span class="mw-page-title-main">Thyroid nodule</span> Lump of tissue or fluid in the thyroid gland

Thyroid nodules are nodules which commonly arise within an otherwise normal thyroid gland. They may be hyperplastic or tumorous, but only a small percentage of thyroid tumors are malignant. Small, asymptomatic nodules are common, and often go unnoticed. Nodules that grow larger or produce symptoms may eventually need medical care. A goitre may have one nodule – uninodular, multiple nodules – multinodular, or be diffuse.

<span class="mw-page-title-main">Myelolipoma</span> Medical condition

Myelolipoma is a benign tumor-like lesion composed of mature adipose (fat) tissue and haematopoietic (blood-forming) elements in various proportions.

<span class="mw-page-title-main">Kidney tumour</span> Medical condition

Kidney tumours are tumours, or growths, on or in the kidney. These growths can be benign or malignant.

<span class="mw-page-title-main">Computed tomography of the abdomen and pelvis</span>

Computed tomography of the abdomen and pelvis is an application of computed tomography (CT) and is a sensitive method for diagnosis of abdominal diseases. It is used frequently to determine stage of cancer and to follow progress. It is also a useful test to investigate acute abdominal pain. Renal stones, appendicitis, pancreatitis, diverticulitis, abdominal aortic aneurysm, and bowel obstruction are conditions that are readily diagnosed and assessed with CT. CT is also the first line for detecting solid organ injury after trauma.

<span class="mw-page-title-main">Renal ultrasonography</span> Examination of one or both kidneys using medical ultrasound

Renal ultrasonography is the examination of one or both kidneys using medical ultrasound.

Ultrasonography of liver tumors involves two stages: detection and characterization.

In CT scan of the thyroid, focal and diffuse thyroid abnormalities are commonly encountered. These findings can often lead to a diagnostic dilemma, as the CT reflects nonspecific appearances. Ultrasound (US) examination has a superior spatial resolution and is considered the modality of choice for thyroid evaluation. Nevertheless, CT detects incidental thyroid nodules (ITNs) and plays an important role in the evaluation of thyroid cancer.

References

  1. ↑ Lumbreras, B; Donat, L; Hernández-Aguado, I (1 April 2010). "Incidental findings in imaging diagnostic tests: a systematic review". The British Journal of Radiology. 83 (988): 276–289. doi:10.1259/bjr/98067945. ISSN   0007-1285. PMC   3473456 . PMID   20335439.
  2. 1 2 3 O'Sullivan, JW; Muntinga, T; Grigg, S; Ioannidis, JPA (18 June 2018). "Prevalence and outcomes of incidental imaging findings: Umbrella review". BMJ . 361: k2387. doi:10.1136/bmj.k2387. PMC   6283350 . PMID   29914908.
  3. ↑ Cook DM (December 1997). "Adrenal mass". Endocrinol. Metab. Clin. North Am. 26 (4): 829–52. doi:10.1016/s0889-8529(05)70284-x. PMID   9429862.
  4. ↑ "2009 AACE/AAES Guidelines, Adrenal incidentaloma" (PDF). Archived from the original (PDF) on 29 August 2017. Retrieved 17 September 2014.
  5. ↑ Grumbach MM, Biller BM, Braunstein GD, et al. (2003). "Management of the clinically inapparent adrenal mass ("incidentaloma")". Ann. Intern. Med. 138 (5): 424–9. doi:10.7326/0003-4819-138-5-200303040-00013. PMID   12614096. S2CID   23454526.
  6. 1 2 Young WF (2007). "Clinical practice. The incidentally discovered adrenal mass". N. Engl. J. Med. 356 (6): 601–10. doi:10.1056/NEJMcp065470. PMID   17287480.
  7. ↑ Theo Falke and Robin Smithuis. "Adrenals - Differentiating benign from malignant". Radiology Assistant. Retrieved 2 January 2018.[ permanent dead link ]
  8. ↑ Cawood TJ, Hunt PJ, O'Shea D, Cole D, Soule S (October 2009). "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?". Eur. J. Endocrinol. 161 (4): 513–27. doi: 10.1530/EJE-09-0234 . PMID   19439510.
  9. ↑ Hall WA, Luciano MG, Doppman JL, Patronas NJ, Oldfield EH (1994). "Pituitary magnetic resonance imaging in normal human volunteers: occult adenomas in the general population". Ann. Intern. Med. 120 (10): 817–20. doi:10.7326/0003-4819-120-10-199405150-00001. PMID   8154641. S2CID   23833253.
  10. ↑ Molitch ME (1997). "Pituitary incidentalomas". Endocrinol. Metab. Clin. North Am. 26 (4): 725–40. doi:10.1016/S0889-8529(05)70279-6. PMID   9429857.
  11. ↑ Snyder (2021). "Causes, presentation, and evaluation of sellar masses" .{{cite journal}}: Cite journal requires |journal= (help)
  12. 1 2 Steele SR, Martin MJ, Mullenix PS, Azarow KS, Andersen CA (2005). "The significance of incidental thyroid abnormalities identified during carotid duplex ultrasonography". Archives of Surgery. 140 (10): 981–5. doi:10.1001/archsurg.140.10.981. PMID   16230549.
  13. ↑ Castro MR, Gharib H (2005). "Continuing controversies in the management of thyroid nodules". Ann. Intern. Med. 142 (11): 926–31. doi:10.7326/0003-4819-142-11-200506070-00011. PMID   15941700. S2CID   41308483.
  14. ↑ Shetty SK, Maher MM, Hahn PF, Halpern EF, Aquino SL (2006). "Significance of incidental thyroid lesions detected on CT: correlation among CT, sonography, and pathology". AJR. American Journal of Roentgenology. 187 (5): 1349–56. doi:10.2214/AJR.05.0468. PMID   17056928.
  15. ↑ Papini E, Guglielmi R, Bianchini A, et al. (2002). "Risk of malignancy in nonpalpable thyroid nodules: predictive value of ultrasound and color-Doppler features". J. Clin. Endocrinol. Metab. 87 (5): 1941–6. doi: 10.1210/jcem.87.5.8504 . PMID   11994321.
  16. ↑ Jenny Hoang (5 November 2013). "Reporting of incidental thyroid nodules on CT and MRI". Radiopaedia ., citing:
    • Hoang, Jenny K.; Langer, Jill E.; Middleton, William D.; Wu, Carol C.; Hammers, Lynwood W.; Cronan, John J.; Tessler, Franklin N.; Grant, Edward G.; Berland, Lincoln L. (2015). "Managing Incidental Thyroid Nodules Detected on Imaging: White Paper of the ACR Incidental Thyroid Findings Committee". Journal of the American College of Radiology. 12 (2): 143–150. doi:10.1016/j.jacr.2014.09.038. ISSN   1546-1440. PMID   25456025.
  17. ↑ Furtado CD, Aguirre DA, Sirlin CB, et al. (2005). "Whole-body CT screening: spectrum of findings and recommendations in 1192 patients". Radiology. 237 (2): 385–94. doi:10.1148/radiol.2372041741. PMID   16170016.
  18. ↑ Gould MK, Fletcher J, Iannettoni MD, et al. (2007). "Evaluation of Patients With Pulmonary Nodules: When Is It Lung Cancer?: ACCP Evidence-Based Clinical Practice Guidelines (2nd Edition)". Chest. 132 (3_suppl): 108S–130S. doi:10.1378/chest.07-1353. PMID   17873164.
  19. ↑ Reddan DN, Raj GV, Polascik TJ (2001). "Management of small renal tumors: an overview". Am. J. Med. 110 (7): 558–62. doi:10.1016/S0002-9343(01)00650-7. PMID   11343669.
  20. ↑ Remzi M, Ozsoy M, Klingler HC, et al. (2006). "Are small renal tumors harmless? Analysis of histopathological features according to tumors 4 cm or less in diameter". J. Urol. 176 (3): 896–9. doi:10.1016/j.juro.2006.04.047. PMID   16890647.
  21. ↑ Content initially copied from: Hansen, Kristoffer; Nielsen, Michael; Ewertsen, Caroline (2015). "Ultrasonography of the Kidney: A Pictorial Review". Diagnostics. 6 (1): 2. doi: 10.3390/diagnostics6010002 . ISSN   2075-4418. PMC   4808817 . PMID   26838799. (CC-BY 4.0)
  22. ↑ Park HJ, Jeon YH, Rho MH, et al. (May 2011). "Incidental findings of the lumbar spine at MRI during herniated intervertebral disk disease evaluation". AJR Am J Roentgenol. 196 (5): 1151–5. doi:10.2214/AJR.10.5457. PMID   21512084.
  23. ↑ Mirilas P, Skandalakis JE (2002). "Benign anatomical mistakes: incidentaloma". The American Surgeon. 68 (11): 1026–8. PMID   12455801.
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