Most words in a CT or ultrasound report describe what a finding looks like, not what it is: a lesion is any abnormal area, and a nodule or mass is a lump; all three can be benign or malignant [1]. Hypodense means darker than the surrounding tissue on CT; a simple liver cyst is hypodense, and a small liver lesion in someone with no risk factors is usually benign [5]. A reactive lymph node is a lymph node that has grown in response to an infection and is usually benign [12]; always go through the report with the doctor who ordered the scan.
Key points
- Most report words only describe what a finding looks like; a "lesion", "nodule" or "mass" can each be benign or malignant [1].
- Unremarkable means "nothing abnormal was seen"; it is good news [2].
- Hypodense means darker than the surrounding tissue on CT; a simple liver cyst is hypodense too. A liver lesion smaller than 1 cm in someone without cancer or liver disease is usually benign [5].
- Incidental findings are very common, and kidney cysts, liver haemangiomas and small adrenal nodules are harmless most of the time [6, 7, 8].
- The phrase "cannot be excluded" caused the most worry in one study; ask your doctor what it means in your case [3].
What does lesion mean? What are a nodule, a mass and a cyst?
In the report, the radiologist (a doctor who specialises in reading scans) describes what they saw, compares it with your earlier scans and, at the end, writes a summary and a suggestion for the next step [1]. Most words only say what a finding looks like, not what it is [1]:
- Lesion: a general name for any abnormal or damaged area. Wounds, abscesses, cysts and tumours are all "lesions"; a lesion can be benign (not cancer) or malignant (cancer) [1].
- Nodule: a growth or lump that can be benign or malignant [1].
- Mass: a lump in the body. It can be caused by an abnormal growth of cells, a cyst, hormonal changes or an immune reaction; a mass can also be benign or malignant [1].
- Cyst: a closed sac that may be filled with fluid, air or other material; most cysts are benign [1].
So seeing the word "lesion" or "mass" in a report does not mean cancer. The most important part of the report is the summary at the end (Impression or Conclusion) and the suggested next step [1].
What does unremarkable mean on a CT scan? Common report terms in plain English
| Term in the report | What it means | Note |
|---|---|---|
| Unremarkable or normal | Nothing abnormal or worth noting was seen | Good news; in one study, 1 in 5 people did not know this word was good news [2] |
| Lesion | Any abnormal area | Can be benign or malignant [1] |
| Nodule or mass | A lump or growth | Can be benign or malignant [1] |
| Cyst | A closed sac filled with fluid or other material | Most cysts are benign [1] |
| Hypodense (hypoattenuating) | On CT, darker than the surrounding tissue | Seen in simple cysts and also in some tumours; not a diagnosis on its own [5] |
| Hyperdense or isodense | On CT, brighter than the surrounding tissue, or the same shade | Not a diagnosis on its own; for example, a liver haemangioma looks the same shade as the liver or brighter after contrast dye is injected [5] |
| Hypoechoic or hyperechoic | On ultrasound, darker or brighter than the surrounding tissue | Not a diagnosis on its own; a typical liver haemangioma is bright (hyperechoic) on ultrasound [6] |
| Hypointense or hyperintense | On MRI, darker or brighter than the surrounding tissue | The meaning depends on the type of image; a haemangioma is dark on T1 images and very bright on T2 images [6] |
| Enhancement (enhancing lesion) | Becomes brighter after contrast dye is injected, meaning it has a blood supply | A simple cyst does not take up contrast; a solid part that enhances, for example in a kidney cyst, is more suspicious and needs further tests [5, 8] |
| Incidental finding | A finding unrelated to the reason the scan was done | Very common; the chance that it is cancer differs from organ to organ [4] |
| Too small to characterise | So small that its type cannot be worked out exactly | Radiologists usually have no concern about it [3] |
| Cannot be excluded or not excluded | The possibility cannot be ruled out completely | Caused the most worry in one study; ask your doctor what it means in your case [3] |
| Stable or unchanged | No change since the previous scan | Reassuring; a liver or adrenal lesion that has not grown for a year is very likely benign [5, 7] |
| Reactive lymph node | A lymph node that has grown in response to an infection, often a viral one | Usually benign and shrinks on its own [12] |
| Clinical correlation recommended | The radiologist asks your doctor to weigh the finding against your history, examination and tests | The scan alone is not enough, and what a finding means depends on your medical history [5] |
No single word proves or rules out cancer on its own; go through the report with your doctor.
Breast and thyroid ultrasound terms have their own meanings; see Hypoechoic breast mass, fibroadenoma and breast cyst, What does my BI-RADS score mean? and Thyroid nodules and TIRADS. If you have had a biopsy, read the guide to reading a pathology report.
What does hypodense mean? What is a hypodense lesion in the liver?
On a CT scan, each tissue looks brighter or darker depending on how much of the X-ray beam it absorbs, and this "density" is measured with a number called the Hounsfield unit (HU) [5]. "Hypodense" means an area darker than the surrounding tissue. A simple liver cyst, which is fluid, looks hypodense, even and sharply outlined; but some tumours also look darker than the liver, so being hypodense is not a diagnosis on its own [5].
Liver lesions are very common: up to 3 in every 10 people over 40 have a lesion in the liver, and most are benign [5]. The most common benign liver lesions are simple cysts, haemangiomas (a cluster of blood vessels), FNH (a benign lump made of liver cells) and changes in blood flow or fat in part of the liver [5].
To decide what to do, the radiologist weighs how the lesion looks against your level of risk [5]:
- If you have no known cancer, no cirrhosis and no risk factor for liver disease (such as hepatitis, inflammatory fatty liver disease or heavy alcohol use), a lesion smaller than 1 cm is usually benign and needs no further tests [5].
- A lesion with the clear features of a cyst or a haemangioma needs no follow-up, whatever your level of risk [5].
- If you have a cancer that can spread to the liver, or you have cirrhosis or hepatitis, even a small lesion is usually checked or followed with MRI [5]. See What are liver metastases? and Symptoms of liver cancer.
These features lead the radiologist to suggest further tests, usually MRI: a blurred edge, an uneven inside, a thick wall or a bump on the wall, and growth on later scans. A lesion that has not grown for a year is very likely benign [5].
Liver haemangioma or cancer? How they differ on ultrasound
A haemangioma is the most common liver tumour, and it is benign. In imaging studies, about 1 in every 20 people has a liver haemangioma; it is found most often in women aged 30 to 50 and is usually small (under 4 cm) and single [6]. Most haemangiomas cause no symptoms and are found by chance [6].
In someone with a healthy liver, a bright (hyperechoic) lesion on ultrasound is very likely a haemangioma. If it looks completely typical (evenly bright, with a sharp edge) and is smaller than 3 cm, ultrasound is enough to make the diagnosis [6]. If it does not look typical, a CT scan, MRI or contrast ultrasound is needed; in someone with cirrhosis, hepatitis or cancer, MRI is usually done as well [5, 6].
On scans with contrast dye, a haemangioma has a typical pattern: first its edges fill with patches of contrast, and then it gradually fills towards the centre. Malignant tumours usually look darker than the liver in the later phase [5]. A typical haemangioma needs no follow-up imaging, and pregnancy or the contraceptive pill is not a problem with a stable haemangioma that causes no symptoms [6].
What is a reactive lymph node?
A "reactive lymph node" is a lymph node that has grown in response to an infection, often a viral one. Swollen lymph nodes are benign in most people and settle on their own [12]. A node larger than 1 cm, or one with an unusual firmness, is usually considered "enlarged" or abnormal [12].
When a lymph node is worrying, and what report terms such as "fatty hilum", "round" or "short axis" mean, is explained on the page What does reactive lymph node mean? Terms in ultrasound and CT reports.
What is an incidental finding on a CT scan?
An incidental finding is something seen on a scan that has nothing to do with the reason the scan was done; for example, a CT scan for pain in the side shows a cyst in the liver [4, 5]. These findings are very common: on some scans, such as a chest CT, something incidental is seen in more than 1 in every 3 people [4].
The chance that an incidental finding is cancer differs from organ to organ. In the brain, the parotid (salivary) gland and the adrenal gland, fewer than 1 in every 20 is cancer; in the breast, kidney, thyroid and ovary the chance is higher, and the finding should be followed up as your doctor advises [4].
Imaging guidelines try to keep harmless findings from leading to needless tests and worry, without missing important ones [5, 7]. The most common incidental findings in the abdomen are covered below. If a lump has been seen in a child's abdomen, see Wilms tumour and neuroblastoma in children.
Adrenal nodule: is it dangerous?
The adrenal glands are two small glands on top of the kidneys that make hormones. An incidental nodule or mass in these glands is common and is seen in about 3 to 7 in every 100 adults. The most common type is a benign "adenoma" that does not make extra hormones [7].
- A nodule smaller than 1 cm usually needs no follow-up [7].
- If the report says the nodule contains obvious fat, is a cyst, or has a density of 10 Hounsfield units or less on a CT scan without contrast, it is benign and needs no follow-up [7].
- A nodule that has not grown for a year or more is very likely benign [7].
- Even in someone with cancer, an incidental adrenal nodule is benign most of the time; but because cancer sometimes spreads to this gland, a dedicated adrenal CT or further tests are usually done [7].
- A mass of 4 cm or more without benign features, in someone with no history of cancer, is usually removed with surgery [7].
A scan cannot tell whether a nodule is making extra hormones; for this reason, hormone tests are also suggested for most incidental adrenal nodules [7].
Kidney cysts and the Bosniak classification: what is a Bosniak 2F cyst?
| Bosniak | Appearance | What it means | Next step |
|---|---|---|---|
| I | A simple cyst with a very thin wall, filled with fluid [8] | Benign [8, 9] | No follow-up needed [8] |
| II | A cyst with a few very thin inner walls or a little calcium [8] | Benign [8, 9] | No follow-up needed [8] |
| IIF (2F) | More thin inner walls, or a slightly thicker wall [8] | Probably benign; a small chance of cancer [8, 9] | Follow-up scans: every 6 months at first, then once a year, for at least 5 years [8] |
| III | A thick, irregular wall that takes up contrast dye [8] | About half are cancer [9] | Referral to a urologist for treatment, or close follow-up in some patients [8] |
| IV | A solid part that takes up contrast dye [8] | About 9 in every 10 are cancer [9] | Referral to a urologist for treatment [8] |
The Bosniak classification is only for kidney cysts; a solid kidney mass is assessed separately.
A Bosniak IIF cyst that does not change for 5 years is considered stable and of no importance [8]. Growth of a cyst on its own is not a sign of cancer; what matters is a change in how it looks, such as a thickening wall or a new solid part [8]. If the report mentions a "solid mass" in the kidney larger than 1 cm, a referral to a urologist is usually needed, while a smaller solid mass is usually followed with scans [8]. Read more: Symptoms of kidney cancer.
Pancreatic cysts and IPMN: are they dangerous?
Pancreatic cysts are also often found by chance: in about 2 in every 100 abdominal CT scans and about 2 in every 10 MRI scans [10]. Many pancreatic cysts never become cancer. The risk lies almost only in "mucinous" (mucus-making) cysts; the most important of these is IPMN (a mucus-making tumour inside the pancreatic duct), which can turn into cancer over the years [10]. A small IPMN (2 cm or less) in the side branches of the duct usually behaves quietly, and only a small share of them become malignant [10].
For this reason, most small cysts are followed with MRI or CT, usually for about 10 years and up to the age of 80 [10]. These signs call for earlier tests, usually an ultrasound through an endoscope and sometimes a needle biopsy, or a surgeon's opinion [10]:
- A cyst of 3 cm or more, a thick wall, or a bump (nodule) inside the cyst
- Widening of the main pancreatic duct
- Jaundice with a cyst in the head of the pancreas, or a solid part that takes up contrast dye
Read more: Symptoms of pancreatic cancer.
I saw my results before my doctor did: what should I do?
- 1
Find the summary at the end of the report
The "Impression" or "Conclusion" section sums up all the findings and the radiologist's suggestion for the next step [1].
- 2
Feeling worried is normal
In a large study, almost all patients preferred to see their results early, even abnormal ones. But about 1 in every 6 people who got an abnormal result said that seeing it before talking to a doctor made them more worried [11].
- 3
Show the report to the doctor who ordered the scan
What a finding means depends on your history, such as a past cancer, liver disease and your age [5]. Your doctor knows these things and can tell you whether the finding matters.
- 4
- 5
When should I contact my doctor?
Most incidental findings are harmless [4]. But in these cases do not wait for a routine appointment; contact the doctor who ordered the scan within the next few days:
- The report uses words such as suspicious for malignancy or "tumour not excluded", or suggests an early MRI or a biopsy [3, 5]
- A Bosniak III or IV kidney cyst is reported [8, 9]
- A pancreatic cyst with a solid part, a thick wall or a widened duct is reported [10]
- A new liver lesion in someone who has cancer, cirrhosis or hepatitis [5]
- You have a pancreatic cyst and develop yellowing of the skin or the whites of the eyes [10]
Sudden severe abdominal pain, fever and chills with jaundice, or vomiting blood need emergency care: call your local emergency number.
Frequently asked questions
Does lesion mean cancer?
Is a hypodense lesion dangerous?
What does a hypodense liver lesion mean? Is a simple liver cyst dangerous?
A simple liver cyst is benign and, when it looks typical, needs no follow-up [5]. A hypodense lesion smaller than 1 cm in someone without cancer, cirrhosis or hepatitis is also usually benign [5]. If the radiologist suggests MRI, it means the lesion could not be fully worked out on these images, not that something is definitely wrong [5].
My report says "too small to characterise": what does that mean?
It means the finding is so small that its density cannot be measured accurately and its type cannot be worked out. In one study, radiologists had almost no concern about this phrase, but patients were more worried [3]. In the liver of someone with no risk factors, such a small lesion is usually benign [5], and in the kidney a very small, even, well-outlined finding is usually a benign cyst [8].
What does "clinical correlation recommended" mean?
The radiologist only sees the images. This phrase means they are asking your doctor to weigh the finding against your symptoms, examination, tests and medical history, because the same finding can mean different things in two people with different histories [5]. On its own, the phrase is not a sign of danger.
My report mentions an adrenal nodule: do I need hormone tests?
The most common type of adrenal nodule is a benign adenoma that does not make extra hormones, but a scan cannot tell whether a nodule is making extra hormones. For this reason, hormone tests are suggested for most incidental adrenal nodules [7]. Talk to your doctor about it.
Is follow-up with repeated CT scans harmful?
For further tests on a liver lesion, the American College of Radiology guidance prefers MRI, which is more accurate and uses no radiation [5]. For the radiation risk, see Do CT scans cause cancer?
Criteria for incidental liver, adrenal, kidney and pancreatic findings (for doctors)
For physicians
Liver (ACR Incidental Findings Committee, 2017; asymptomatic adults aged 18 years or older, CT done for another reason). Low risk: no known malignancy, hepatic dysfunction or hepatic risk factor; high risk: malignancy with a propensity to metastasise to the liver, cirrhosis or a hepatic risk factor (hepatitis, alcohol, NASH, sclerosing cholangitis, PBC, choledochal cyst, haemochromatosis, anabolic steroids). Low risk: lesions under 1 cm are considered benign; 1–1.5 cm with benign or flash-filling features, no follow-up, and with suspicious features, prompt MRI; over 1.5 cm with suspicious or flash-filling features, prompt MRI. High risk: under 1 cm, MRI in 3–6 months; 1–1.5 cm with suspicious or flash-filling features, prompt MRI; over 1.5 cm without benign features, at minimum prompt MRI, and direct biopsy for large, highly suspicious lesions. Benign features: sharp margin, homogeneous attenuation of 20 HU or less on unenhanced or portal venous phase images, or the typical features of haemangioma, FNH or perfusion and fat changes. Suspicious features: ill-defined margin, heterogeneity, mural thickening or nodularity, thick septa, attenuation over 20 HU on the portal venous phase, or enhancement over 20 HU after contrast. Absence of growth over 1 year strongly favours a benign lesion [5]. A typical haemangioma under 3 cm in a healthy liver is diagnosed by ultrasound and needs no follow-up (EASL 2016, evidence level II-2, grade 1) [6].
Adrenal (ACR 2017). Prevalence 3–7% of adults. Under 1 cm in short axis: no follow-up. Diagnostic benign features (macroscopic fat, cyst, haemorrhage, calcification, density of 10 HU or less on unenhanced CT, or signal loss on chemical-shift MRI): no follow-up. 1 to under 4 cm without diagnostic features: stability for 1 year or more means benign; without a cancer history, adrenal-protocol CT at 12 months (1–2 cm) or at the time of detection (over 2 to under 4 cm); with a cancer history, adrenal-protocol CT (absolute washout of 60% or more or relative washout of 40% or more means adenoma), and PET/CT or biopsy if enlarging. 4 cm or more without benign features and without a cancer history: resection without biopsy. Biochemical evaluation for most nodules (subclinical hyperfunction 5–9%), and plasma metanephrines before any biopsy [7].
Kidney (ACR 2018; Bosniak version 2019). Cysts in up to 40% of CT scans. A homogeneous mass of −10 to +20 HU without enhancement: simple cyst; homogeneous 70 HU or more on unenhanced CT: almost always a hyperdense Bosniak II cyst. An increase of 20 HU or more after contrast: definite enhancement; over 10 to under 20 HU: equivocal. Bosniak I and II: no follow-up; IIF: follow-up every 6 months at first and then yearly, for at least 5 years; III and IV: referral for treatment, with surveillance of III acceptable in limited life expectancy or high surgical risk [8]. In the version 2019 review, about half of resected class III masses (25–100% across series) and about 90% of class IV masses (56–100%) were malignant, and reported malignancy rates in IIF were 0–38%, with selection bias [9]. Solid masses: the chance of being benign is about 40% under 1 cm, about 20% at 1–4 cm and under 10% above 4 cm [8].
Pancreas (ACR 2017). Cysts in 2.2% of upper abdominal CT scans and 19.6% of MRI scans. Malignancy occurs virtually only in mucinous cysts; reported malignancy rates are 12–47% for BD-IPMN, 38–65% for the combined type and 38–68% for the main-duct type. Worrisome features: cyst of 3 cm or more, thickened or enhancing wall, non-enhancing mural nodule, main duct of 7 mm or more. High-risk stigmata: obstructive jaundice with a cyst in the pancreatic head, an enhancing solid component, main duct of 10 mm or more without obstruction. Follow-up for 9–10 years, ending at age 80; significant growth: a 100% increase in long-axis diameter for cysts under 0.5 cm, 50% for 0.5 to under 1.5 cm and 20% for 1.5 cm or more [10].
Report language. In a survey about a 5-mm liver lesion (13 radiologists, 59 referring physicians, 51 patients), "too small to characterise" and "most likely a cyst" carried a median concern of 0% for radiologists, over 0 to 1% for referrers and over 2 to 5% for patients; expressions containing "not excluded" caused the most concern in all groups, and the likelihood of ordering follow-up imaging ranged from 2% ("benign cyst") to 75% ("most likely a cyst, although tumour not excluded"); 76% of referrers wanted the report to state whether follow-up is needed [3]. In an umbrella review, malignancy was found in under 5% of incidentalomas of the brain, parotid and adrenal gland, in about a quarter of those of the kidney, thyroid and ovary, and in 42% of those of the breast [4].
Related cancer types
Related questions
References
12 referencesShow all referencesClose the reference list
Numbers in the text, such as [1], refer to these sources. Sources with a “Study card” button are summarised in the site’s evidence library.
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11Perspectives of Patients About Immediate Access to Test Results Through an Online Patient Portal
- 12
This page is based on reputable scientific sources and was last updated on 28 October 2026. The content of this website is for educational and informational purposes only and does not replace consultation, diagnosis or treatment by a specialist physician. Consult your treating physician about any treatment decision.
Printed from the website; the full and up-to-date version: https://drdabiri.com/en/questions/radiology-report-terms/