Advanced imaging technologies are in routine use, and benign masses are common in our aging population: Together, these realities make it crucial to know when to work up an incidentally discovered lesion. This presentation from radiologist Hailey H. Choi, MD, supplies straightforward criteria to help providers assess lesions ranging from thyroid and adrenal nodules to ovarian cysts to pancreatic and liver lesions.
Hi everyone. My name is Haley Choi, um, I'm not muted. OK, great. Great. Um, so we're going to spend the next couple of minutes talking about incidentalomass. I heard that this was a hotly requested topic, so I hope we're all excited. Um, so we'll get started. Um, Uh, incidentalomas, um, usually refer to findings either masses or lesions that are detected on imaging that's performed for an unrelated reason or in an asymptomatic patient. And um, The incidentalloma dilemma is compounded by the fact that we are performing more imaging in patients and our imaging technology has also greatly improved. So now we're finding more and more of these incidental things. Um, and I think many of us feel that they are of unclear clinical significance, but I hope to change that today, so I hope to leave you with some clinical significance. So the goal of our session today is to really learn how to manage incidental illness. So we'll talk about some of the commonly encountered uh incidentalomas. Um, there are many, many incidental findings. Um, we see them every time we do imaging, but these are the ones we're going to focus on for today. Um, one is thyroid nodules, liver lesions, adrenal nodules, kidney lesions, pancreatic cysts, and ovarian lesions. So these are the topics we will cover today, and we will start with thyroid nodules. So here's a case example. It's pretty common. Um, so it's an, this is an example in an 88 year old patient who has episodic arm tingling, numbness, and we were concerned for cervical radiculopathy. So an MRI of the cervical spine was ordered. And the MRI did show some narrowed areas where um it will be compressing on the nerve roots, um, but it also gave us a bonus finding of an incidental thyroid nodule on the left. So now what? So let's review a little bit about thyroid nodules. Thyroid nodules are an abnormal growth of cells that form a lump inside the thyroid gland. They are extremely common and actually the majority of adults actually have nodules. Uh, most of these are benign. Some turn out to be some, uh, colloid cysts which are fluid-filled sacs, uh, within the thyroid. Um, some are spongiform, uh, containing a mixture of fluid and cells. Uh, and unfort in some cases, uh, imaging alone is not enough to tell whether it is benign or malignant. And even with the case of malignant nodules, this is an example of a papillary thyroid carcinoma here. Um, most of the thyroid cancers exhibit benign indolent behavior, and small cancers, especially those less than 2 centimeters in size, have a nearly 100% uh 10-year survival rate. So pretty good prognosis even at the worst case scenario. Thyroid nodules are often incidentally detected on CT or MRI of the neck or chest, and the CT and MRI, while they can detect the presence of nodules, cannot image them in enough detail for risk stratification. So ultrasound is the best modality here. It can look for features that we know are Associated with malignancy, and these include microcalcifications and lobulated margins, um, as in the example here. Um, but remember that most thyroid cancers have an indolent course. So taking this into account, the American College of Radiology has parameters on when to recommend further workup. Uh, so let's, uh, uh, so I'm going to talk about prevalence a little bit. So the prevalence of benign nodules increases with age and younger patients have a longer life expectancy. So taking these into account, the recommendation is to pursue further workup for nodules, uh, that are at least 1 centimeter in a younger patient less than 35 years of age. And if the patient is 35 or older, then that threshold increases to 1.5 centimeters. If there is evidence of locally advanced disease or any spread to lymph nodes on the CT or MRI that was initially performed, then the thyroid nodule should also be worked up because now we're actually worried that it is, it is malignant. Um, the American Thyroid Association, however, does not recommend ultrasound for every incidental nodule. Uh, but we'll get back to this point in a few slides. I have to bring up FDG PET, so um if there is a thyroid nodule and it's active on the PET CT then we do need to work them up because that already is a little bit of a suspicious feature. Um, this actually gives an example in a patient with metastatic endometrial cancer. Uh, in this patient, um, she was thought to have limited life expectancy, was undergoing serial imaging follow-ups, so no further, uh, dedicated thyroid ultrasound, uh, workup was ordered for this patient, uh, because we would just keep an eye on it on her next surveillance exam. Now, I will try to demystify the magic of thyroid ultrasound. Uh, most radiologists now use a standard approach to characterizing thyroid nodules and recommending the next steps in management, and this is called ACRTRAD. It stands for thyroid Imaging Reporting and Data System. And it basically grades all the nodules from what we think are completely benign to malignant. And so typical benign nodules, as this thyroid's one example here would include colloid cysts, uh, mixed solid and cystic nodules, uh, which are also not suspicious. Um, and, uh, once the nodule has a more solid appearance, then we cannot definitively call them benign. So in this case, it would be given a middle category of Tyret's 3. Coarse calcification, as in this example here is another feature that may or may not be benign. And the most suspicious features are the punctate echogenic fossa, so those are the little white dots you see inside the nodule here and the irregular lobulated borders. Um, even with the highest category of Tyrod's 5, only lesions greater than 1 centimeter will be biopsied. If you can imagine how small that 1 centimeter is, it makes sense. It's very challenging to biopsy a subcentimeter nodule. Um, and this goes hand in hand back to the incidental recommendations. Um, we don't wanna be worked up about anything that's less than 1 centimeter. So let's go back to our patient with the incidental nodule on cervical spine MRI. As you can see, the nodule just appears as a slightly bright blob on the MRI. And the following thyroid ultrasound was performed, and it shows that the nodule has clearly smooth borders, is mostly solid. We didn't find any microcalcifications. So this corresponds to a thyroid's 3 category, and the appropriate recommendation given this category and the size of the nodule was a follow-up uh with ultrasound surveillance in 1 year. To summarize, many, many, many people have thyroid nodules, and especially the older we get. Majority of these nodules are benign, and even if they are malignant, they typically have an indolent course. Thyroid nodules are expected findings in older patients, but younger patients, especially those under 35, it's a little bit atypical and should be regarded with a little bit more suspicion. And what are the next steps for an incidental thyroid nodule? Well, we would want to do a thyroid ultrasound if the nodule is um of adequate size, um, or if we have any highly suspicious features on the CT or MRI or if your patient has a risk factors that would predispose them to thyroid malignancy such as child, uh, childhood radiation exposure. All right. So that concludes our thyroid and we will move on to our next target, which is adrenal nodules. Adrenal nodules are also quite common. About 45% of patients undergoing abdominal CT actually turn out to have adrenal nodules. And the prevalence also increases with age. So it's, the prevalence is estimated to be 0.5% in those younger than 20 years old, but as many as 7% in those older than 70. Adrenal nodules are almost always benign, and these benign nodules can be definitely diagnosed by imaging and biopsies are rarely needed. So let's go over some ground rules. 1 centimeter, again, is a size threshold for defining an adrenal nodule. Nodules smaller than that are thought to be insignificant, um, except if the patient has signs of a hormone-secreting tumor. Nodules larger. Than 4 centimeter actually needs surgical consultation unless it contains fat, in which case we know it's a benign nodule. But we'll talk about this again. So the upper size threshold is because larger nodules tend to be malignant either from metastatic disease or adrenal cortical carcinoma, and this was a really large uh left adrenal nodule that turned out to be adrenal cortical carcinoma. Most adrenal nodules fall into two categories, um, adenomas and myelolipoma. So we'll talk about adenomas first. So adenomas are benign tumors that arise from the adrenal cortex. Some adenomas can secrete hormones, uh, glucocorticoid or aldosterone, leading to Cushing's syndrome and uncontrolled. Hypertension, respectively. Um, here's an example of a lipid-rich adenoma. It is a non-contrast CT and you can see a rounded nodule on the, in the left adrenal gland, and the density of this is quite low, less than 10 pounds field units. And that's the thing that definitely characterizes this lesion as a benign adenoma. The low density comes from intracytoplasmic lipid that these adenomas have. Some adenomas, however, are lipid-poor and they cannot be diagnosed based on this density feature alone. In this case, an adrenal CT is required to characterize the enhancement and washout pattern. So with these lipid-poor adenomas, you would do an adrenal. And that would show that the adenoma enhances brightly earlier on and then washes out, um, most of the part enhancement washes out by 15 minutes. Um, and this washout pattern definitely diagnoses the nodule as a lipid 4 adenoma. The other benign entity that's pretty commonly encountered is an adrenal myelolipoma, and this is a tumor that's composed of fat and bone marrow elements. This nodule is characterized also by its super low density, so you can see the nodule on the right adrenal gland here pointed by the. Arrow and you can look at the internal household unit or just the density or the color of the nodule and it looks very similar to the retroperitoneal fat around it. So this is what makes this diagnosis of uh an adrenalyelolipoma which are also benign. Usually, uh, when we encounter adrenal nodules, incidentally, the radiologist should be evaluating the nodule for these lipid and fat contents, uh, which would diagnose them as benign, and if these features are present, then we don't need to do any further work. There are some non-tumor benign entities of the adrenal gland as well. So for example, this is an adrenal hematoma. So I'm showing you an uh a nodule, nodule in the left adrenal gland on a non-contrast and a contrast enhanced CT in the same patient. And you can see that it is Intermediate density or high density on the non-contrast has no visible enhancement. Uh, so this confirms, uh, this is a case of an adrenal hematoma. This results from bleeding into the adrenal gland, which can be from trauma or bleeding into an existing nodule. And again, the key to this benign diagnosis is that the nodule is intermediate to high density on non-contrast imaging and has no enhancement. Two other benign entities include lymphangioma and adrenal cyst. Both of these are very low density lesions, um, looking very similar to a simple fluid density, and again, no enhancement. There are a few rare exceptions though. Uh, renal cell carcinoma and hepatocellular carcinoma can sometimes contain intracellular fat and also exhibit the rapid enhancement and washout pattern. Uh, these characteristics overlap with the features we've just described for the adrenal adenomas, and for the most part, unless the patient has existing history or risk factors for RCC or HCC, this won't be a problem because adenomas are just so much more common, and the chances are overwhelmingly in favor of it being a benign adrenal nodule. Theochromocytoma can also exhibit contrast washed out similar to that of adrenal adenomas. Uh, another tricky situation is finding an adrenal nodule in a patient with known or recently diagnosed malignancy, and the key here would be to look at the prior imaging to assess for the stability of the nodule. Was the nodule there a long time before the primary malignancy was diagnosed? If so, then it's probably benign. Another useful tool here is to consider PET CT. Taking all of the things together, I'll go through what the radiologist's algorithm and next steps for incidentally detected adrenal nodules would be. The first thing to do is to look at the nodule and look for lipid or fat content that would characterize the nodule as adenoma or myelolipoma. If it is there, then the finding is benign. We don't need to do anything. If the nodule isn't definitely benign and is large, uh, at least 4 centimeters, then the surgery should be consulted for resection. If the nodule is between 1 and 4 centimeters in size and still indeterminate, then we want to do an adrenal CT in 12 months. Adrenal CT is performed with and without contrast, and this is really to look at that lipid 4 adenoma appearance that we talked about. To summarize, adrenal nodules are common and are almost always benign. Most nodules end up being adenomas or myelolipomas, which are completely benign entities. If the nodule is not definitively benign and at least 4 centimeters, then surgical resection should be considered. Um, in all other instances, a follow-up adrenal CT may be required. That sums up adrenals and we'll move on to our next target, which is liver. Liver lesions are also quite common, seen in as many as 30% of adult patients older than 40. Both benign and malignant liver lesions are common, so management is not as easy as for adrenal nodules. Some commonly Encountered benign lesions include hepatic cysts, hemangiomas, um, and, uh, to name a few. And for malignant lesions, we would be worried about metastasis from uh and primary liver cancer, um, also known as hepatocellular carcinoma. And so because both benign and malignant lesions are common in the liver, uh, the management depends on your patient, uh, specifically risk factors. So if the patient has a known malignancy or risk factors for malignancy, especially those known to metastasize to the liver, so anything arising from the GI tract, breast, or lung cancer, then you might wanna be a little bit more cautious. Uh, the other category of risk factors is for developing HCC. So any patient with cirrhosis, chronic hepatitis B, um, NASH with advanced fibrosis, um, all of those things here would raise your suspicion in the incidental liver lesion that was detected. Uh, let's go over some ground rules again. So if we know that it's benign, then we don't need to worry about them. We don't need to follow them up. Um, if your patient has no risk factors and you find a tiny, tiny lesion that's less than 1 centimeter, we don't need to be worried about them. Sometimes we encounter a smallish, uh, so 1 to 1.5 centimeter lesions that are homogeneously enhancing. Um, most, for the most part, these are flash-filling hemangiomas, and we'll talk about this in a little bit, um, which are benign. So if your patient has no risk factors and you encounter this small enhancing lesion, uh, we don't need to worry. If your patient has risk factors that we just talked about and you find a hypodense lesion that's less than 1 centimeter, then we wanna consider doing follow-up. Um, if you find something that kind of looks like a flesh-filling hemangioma, so a smallish enhancing lesion, uh, in a patient with risk factors, we need to do further workup with multi-phase CT MRI, or contrast enhanced ultrasound. Um, and if at any point, the lesion is not clearly benign, then we want to do further evaluation with dedicated liver imaging. In select instances, if your suspicion is very high, you can also consider tissue sampling. Hepatic cysts are incidentally found the fluid-filled cavities inside the liver. They are lined by fibrous tissue and epithelial cells, and the exact pathophysiology for this is not entirely clear. Um, people think that it might be a benign developmental malformation. Um, uh, hepatic cysts are benign, mostly asymptomatic, and don't require any further workup or intervention. If it is very large and causing patients symptoms such as abdominal pain or if it's complicated by a superimposed infection, then we might Want to do some intervention, but for the most part, incidentally, detected hepatic cysts don't require any follow-up. So here's an example from a laparoscopic image, but I can show you some other examples on imaging. So here's a hepatic cyst on ultrasound. It's the black hole that you see in the liver there and CT. It's a hypodense rounded structure in the posterior right hepatic lobe. And on MRI it, uh, this is a T2 weighted or fluid sensitive sequence and you can see that it is bright because it's filled with that fluid. Hemangiomas, also called cavernous hemangiomas, are also benign neoplasms in the liver. They are composed of dilated vascular spaces, uh, also mixed with some fibrous tissue. Uh, they are very common, uh, occurring in as much as 20% of the general population. Hemangiomas can be definitely diagnosed as imaging because it has a very classic distinct enhancement pattern. So I'll show you that. So here's an MRI, um, abdominal MRI in a patient with a hemangioma, and this is the arterial phase or early on, uh, imaging, um, imaged early after, uh, we inject a contrast, and you can see along the periphery of the liver, uh, of The lesion, you could see puddles of enhancement. And as we watch the areas over time, it becomes larger and the entire lesion, uh, starts to fill in. So this peripheral nodular enhancement with progressive filling is the diagnose uh uh is the key to making this diagnosis of hemangioma. Um, I'm going to show you a contrast enhanced. Ultrasound, the image of hemangioma as well. Um, contrast enhanced ultrasound basically means that we image with ultrasound after we inject microbubble contrast. It is actually the same contrast agent that they use for echocardiograms when looking for shunts. Um, and so we'll look at the same, uh, uh, not the same, but the same type of lesion of hemangioma on contrast against ultrasound. So, we have to let this video play a little bit, uh, and then I'll direct your attention to the periphery of the lesion where you're seeing those similar puddles of enhancement getting, uh, gradually larger over time. So very classic appearance. Small homogeneously enhancing lesions are a bit trickier. Um, in most patients without risk factors, these are most likely smaller versions of those cavernous hemangiomas that we just talked about. Because of its small size, uh, the vascular channels don't take that long to enhance fully. So by the time we inject contrast and take that picture on CT or MRI, we only see a brightly enhancing lesion like this one in the post. Your right hepatic lobe here. Um, but hypervascular malignancies including hepatocellular carcinoma, renal cell carcinoma, neuroendocrine tumor, um, can also look like small brightly enhancing lesions. So based on a, just a single routine CT scan, it may be impossible to distinguish the two apart. So this one's a hemangioma, this one's an HCC. It can look very similar. So, if a patient does, does have risk factors, uh, then we would recommend a short interval follow-up or just further workup with liver uh imaging, uh, just to make sure that it's not a malignancy. Just to show you what indeterminate or not definitely benign lesions look like, here's an example of a patient who underwent partial gastrectomy for high-grade dysplasia of the stomach. Uh, CT shows a very subtle hypoattenuating lesion in the posterior right hepatic globe. It does not look like a cyst, does not look like a hemangioma, so we can't definitely diagnose this lesion as being benign. The appropriate next step would have been to include, um, would have been to do further characterization with dedicated liver imaging, um. But this patient actually ended up having some surgical complications and uh ended up getting follow-up imaging 3 months later. And on the 3-month follow-up, we see the same lesion in the posterior right hepatic lobe, but we also found a new lesion. So taking all of the things into consideration, uh, the findings were concerning for liver metastasis from gastric cancer. To summarize, incidental liver lesions are very common, and many, many, uh, many of them are benign, but malignant liver lesions, whether from mets or primary liver cancer, are also common. Therefore, the management for liver lesions depends on the patient's risk factors for malignancy. If the lesion has definitely benign characteristics such as a cyst or hemangioma, then we don't need to do anything. We don't need to worry about them. If the lesion is very small, less than 1 centimeter, generally they are insignificant. If the patient has a known primary malignancy or any other reason to suspect malignancy, then we should do a follow-up in 3 to 6 months. Uh, if the lesion is greater than 1 or 1.5 centimeters and it's not clearly benign, then further workup should also be performed, and this can include additional imaging with multi-phase CT, um, abdominal MRI, or contrast enhanced ultrasound. In select cases with very high suspicion, you can also consider tissue sampling. OK, that wraps up our liver area, so we'll move on to our next target, which is pancreas. Particularly with recent advances in imaging, we are finding more and more pancreatic cystic lesions in as many as nearly 20% of abdominal MRIs. Uh, these pancreatic cystic lesions are pockets of fluid in the pancreas. They can be, uh, uh, the result of a prior inflammation, uh, which would be non-neoplastic, but they can also reflect new op la s m s So, while the risk of malignant progression of the cystic lesion, uh, is pretty low, um, in other words, only a few of these cystic lesions progress to progress on to being a full-on malignancy, pancreatic cancer is a pretty deadly disease with very poor prognosis. Therefore, it is a little bit difficult to do nothing about these incidental findings. There are several pancreatic cyst subtypes or cystic lesion diagnosis. Um, the first thing is a pseudocyst. Uh, this is a result of pancreatitis and is not a neoplasm. It's a post-inflammatory or inflammatory condition. Uh, to make this diagnosis, we would need to confirm the patient's medical history for any prior episodes of pancreatitis. Neoplasms containing mucin, so these would include mucinous cystic neoplasms, intraductal papillary mucinous neoplasms or IPMNs, uh, which can be within the main duct or side branch ducts. These are the ones that we're actually concerned about. Um, these mucinous neoplasms can progress from lower to higher grades of dysplasia and ultimately pancreatic adenocarcinoma. Uh, other differential diagnoses would include a cystic neuroendocrine tumor and serous cystadenoma, but these entities should have either imaging or clinical features that are more specific, uh, and lead to the specific diagnosis. So those are not of the concern, uh, usually when we're talking about incidental pancreatic cystic lesions. Unfortunately, for these cystic lesions, uh, cystic mucinous lesions, it's difficult to predict this behavior based on the initial assessment. So for example, in this case, there is an oblong cystic lesion in the pancreatic body. This cystic lesion was followed over 8 years and remained the same. No mural nodules, no solid components to suggest that it has morphed into a malignancy. While some cysts they stayed the same over many years, others are not so benign. Uh, so in this case, um, our lesion started out as a tiny cystic focus in the uh pancreatic tail. Over time, it slowly enlarged, and by 2017, it even developed solid nodules. Um, this turned out to be pancreatic adenocarcinoma, so these are the ones that we want to diagnose early by doing serial imaging. In general, uh, there is a low rate for malignant transformation in these cystic lesions. Uh, the malignancy rates for bile duct IPMNs range from 12 to 47% and for main duct it's higher at 38 to 68%. But these rates, um, are likely overestimating the risk of malignancy cause, uh, due to selection bias. So only patients who had surgical resections would have been. Included in the study, therefore, elevating uh the malignancy rates. Um, so the data is unclear, particularly for small incidental pancreatic cystic lesions, and some more data is emerging now to suggest that they have indolent behavior with only a few progressing to malignancy. But for the most part, for now, um, we would, we would recommend surveillance. Uh, and there is also limited evidence on how exactly to manage the pancreatic cystic lesions. Several societies have developed recommendations for management strategies. Uh, some recommend lifelong surveillance, some recommend less frequent, shorter duration surveillance. And what all of these recommendations are trying to do is balance the cost and morbidity of surveillance and potential interventions on benign lesions against the opportunity to prevent or early diag diagnose early uh potentially fatal cancer. Most radiologists, uh, use the American College of Radiology recommendations. Uh, this is somewhat of a happy medium between the most stringent and most lenient versions of the guidelines. Um, and the management recommendations are based on, uh, any presence of high-risk stigmata, uh, cyst size, age, or patient's age, uh, and whether the cyst communicates with the main pancreatic duct or not. Um, And when we're doing the serial imaging for follow-up, and we also assess for the growth rate of the cystic lesion. Uh, so, general rules or general overview is that we will want to do surveillance for about 10 years, um, and the surveillance can be performed with an abdominal MRI or multiphase CT that's dedicated, uh, with a pancreas protocol. Uh, the time interval can vary between 1 or 2 years based on how suspicious that lesion looks. Um, we can also consider endoscopic ultrasound and FNA for large or growing lesions. And if any worrisome features develop, then we would also want to do surgical consultation. And these worrisome features would include neural nodules, especially if they're enhancing, any wall thickening, any associated dilatation of the main pancreatic duct, peripheral calcification, and important, um, any signs of biliary obstruction, including jaundice. So these would be the worrisome features we will be looking for. So pancreatic cysts are becoming more and more common, um, partly because our imaging started, uh, tech uh technique is also getting better. Um, they generally have a low rate, uh, of progression to frank malignancy, um, but because pancreatic cancer is so deadly, we would recommend long-term follow-up, uh, with MRI or a CT. All right. Uh, we're going to move on to kidney lesions. Uh, renal lesions are also really common incidental findings with a prevalence ranging from 13 to 27% in the adult population, and the incidence again increases with age. More than half of patients over age 50 have a renal lesion. Most of these turn out to be benign cysts. Um, and in addition to benign renal cysts, other benign, uh, renal masses would include angiomyolipomas or onchocytomas. Um, and, uh, less frequently these renal lesions are actually malignant neoplasms, such as renal cell carcinoma or metastasis from other primary cancer. Um, in the case of renal cell carcinoma, and especially for small RCCs, um, the, uh, there's a good prognosis. Uh, so many small RCCs actually have an indolent course. With this background info in mind, let's review some basic rules for an incidental renal lesion. If the lesion is clearly benign, then we don't need to do anything. If it is small, less than 1 centimeter, hypodense or hypo-enhancing lesion, it most likely reflects a small cyst. So we also don't need to do, uh, don't need to be concerned. If it's a small but enhancing, definitely enhancing mass, then it could be a, a very small, uh, RCC, so we would want to do follow-up. And everything else, uh, that is not clearly benign requires further imaging with dedicated renal mass protocol. It can be done with a multiphase CT, abdominal MRI, contrast enhanced ultrasound. Um, and sometimes if we're uh not super concerned and think that it might just be a complicated cyst, um, just ultrasound alone can confirm the cyst. Uh, nature of a lesion. Simple renal cysts are thin walled sacs filled with fluid. Uh, the exact cause for developing such small cysts or developing cysts are not well known, and, uh, some conditions such as end-stage renal disease and long-term lithium use may be associated with multiple small renal cysts. Renal cysts are benign and no further workup. is warranted unless the cyst is very large and the patient is symptomatic. On CT, the renal cyst is homogeneously hypodense with simple fluid attenuation. On MRI, they follow the signal of water, so you can see this one and again this is fluid sensitive T2 weighted image and you could see a bright lesion in the right kidney and the color of that lesion is the same as CSF. Um, and on ultrasound, there should be rounded lesions with thin walls and completely black or anachromic inside. Some renal cysts, however, are not so simple. In some cases, there may have been some bleeding or pertinaceous skunk that was building up inside the cyst, and this corresponds to a hyperdense cyst on imaging. As in this example here. It's a non-contrast CT and the attenuation of the left renal lesion is quite dense. So this is consistent with a cyst with hemorrhage. Some renal cysts may contain septations. And as long as the septations are thin and few in number, they are still considered benign and no further workup is necessary. This is an example of an incidental renal lesion that is not clearly a cyst. Uh, it's also in the left kidney. It has a slightly heterogeneous appearance with areas that appear denser than uh simple fluid. In this case, we opted for ultrasound and contrast enhanced ultrasound for further evaluation. The ultrasound image here shows a cyst with some bright stuff on the back, um, and this is, uh, layering material, um, like the, uh, some debris inside the cyst. We also performed a contrast injection with ultrasound, and you could see the cyst area again. Um, go back. Uh, if you look at the arrows that corresponds to the cyst and after we inject contrast, there's no enhancement inside the cyst. So this confirms the diagnosis of a renal cyst with hemorrhage. Here's a different example. In this right kidney this time, there is a partially exophytic lesion with heterogeneous appearance, density definitely greater than simple fluid. And again, this is a case that needs further diagnostic imaging. I have another case of contrast enhanced ultrasound here. Um, we'll let this clip play once and then I'm gonna direct you with the arrows, so focus on the arrows. This is a lesion, a corresponding lesion on ultrasound, and it enhances brightly after contrast administration. So this is consistent with a renal cell carcinoma. So renal lesions that are not clearly benign need further workup. For small enhancing lesions, these may turn out to be small RCCs, but these small RCCs may not grow and have a relatively non-aggressive behavior and are less likely to metastasize. So balancing the cost and potential complications from surgical treatment and potentially losing uh valuable nephrons, many specialists now opt for active surveillance. And so this goes hand in hand back with our ACR recommendations. These small lesions can be followed in 6 to 12 months. Angiomyolipoma or AMLs are benign neoplasms composed of smooth muscle, blood vessels, and fat. They are less commonly encountered incidental findings, and most cases are actually sporadic, but a few cases can be associated with tuberous sclerosis, in which case There probably will be multiple bilateral AMLs. When AMLs are greater than 4 centimeters, they have some bleeding risk. In these cases, a discussion with urology or interventional radiology may be fruitful to uh discuss options for elective, uh, prophylactic uh resection or embolization. This is the classic appearance of AML on CT. So there's an exophytic lesion arising from the left kidney. It's very hypodense. Uh, the CT Hansfeld units are similar to that of adjacent retroperitoneal fat, and the presence of this chunk of fat is the key to diagnosis. We know that it's an AML, a benign lesion, and no further workup is needed. Um, typical angiomyolipomas don't contain calcium, so if a lesion contains both fat and calcium, it can technically be an RCC. In this case, uh, in that case, further imaging should be performed. Another benign lesion, uh, we talked about was onchocytomas. Uh, onchocytomas are benign neoplasms that arise from the interrelated cells that line the distal tubules and collecting ducts within the kidney. Uh, these neoplasms are benign with an excellent prognosis. But they present as a diagnostic challenge because they look exactly like RCCs. So here I'm showing you onchocytoma, RCC. Uh, they're both bright, uh, enhancing solid lesions. Uh, so based on the imaging, we can't tell them apart and for that reason, most of, uh, oncocytomas are typically resected. So to uh to cap our findings, um, our discussion for renal lesions, most of them are benign. If they're not clearly benign, we need to do further imaging and this should be done with a multi-phase CT, abdominal MRI, or contrast enhanced ultrasound. Um, we want to give a little bit of time before we proceed to imaging for small lesions. So remember that, uh, even small RCCs have a very slow growth rate. Um, it's difficult to characterize a very small lesions on the imaging, so we wanna get that, uh, get that, uh, time interval to our advantage. OK, next topic. And our final topic is ovarian lesions. Um, these are also commonly encountered on imaging, any CT, MRI, or ultrasound that includes the pelvis. Most incidentally detected lesions are actually benign, um, reflecting physiologic changes that are expected for a reproductive age female patients and some small simple cysts without any malignant potential. However, the presence of any ovarian lesion actually causes a lot of alarm in many patients who may be concerned that it would be ovarian cancer. Um. And just remember that the differential diagnosis and diagnostic algorithm are different for pre premenopausal versus postmenopausal patients. Um, again, 1, less than 1 centimeter findings are likely insignificant, do nothing. Pelvic ultrasound or MRI is definitely better than CT in characterizing a nexal or ovarian lesions. Uh, most benign lesions, we don't need to do any further action. Um, in some benign entities, you might want to get gynecology consult or uh some uh surveillance or follow-up imaging, but we'll discuss that in a little bit. Any lesion that has suspicious features or a very large cyst uh requires further evaluation with ultrasound or MRI. So let's talk about the reproductive age patients or premenopausal patients. Many changes happen with the menstrual cycle, and this includes the ovaries. As you can see in this diagram, the ovaries actually undergoes the entire transformation. So follicles develop, mature follicle, ovulation, and it becomes a corpus luteum and then the corpus luteum involutes over time. So lots of different appearances. And so let's go over that a little bit. Uh, immediately after menses, um, early, in the early proliferative phase, um, you don't really have any abdominal follicles yet, just some atrial follicles, um, and by day 8 or 12. Mm But day 8 or 12, 1 of the follicles becomes dominant. It reaches a size of about 2 or 2.5 centimeters. Um, sometimes it is larger than that, uh, sometimes larger than 3 centimeters or even larger. Um, and these probably account for a lot of the incidental findings that we encounter. Um, also, sometimes abdominal follicles can undergo internal hemorrhage, um, and that would be a hemorrhagic cyst. After ovulation, the mature follicle becomes a corpus luteum. It's characterized on ultrasound by this, uh, the thick vascular walls, um, and if the egg is not fertilized, um, then this corpus luteum regresses in the late secretory phase, so it slow slowly, uh, becomes smaller and then eventually involutes. Uh, in the postmenopausal patients, uh, they should not be having any ovulation. So these, uh, changes that we just talked about will be unexpected for a postmenopausal patient. And so we have a lower threshold for further evaluation of ovarian cystic lesions in this population. Many of the simple cysts are, that we encounter on imaging are dominant follicles, which are part of normal physiology. We actually we updated our society's guidelines for management of simple cysts. Uh, simple cysts, which are sacks of simple water-like fluid, um, have a very low risk of malignancy. And the risk of malignancy in female patients with simple cysts is not any higher than that of the general population. So Given this information, we actually increase our size threshold for requiring follow-up. Um, if a premenopausal patient, cyst, cysts up to 5 centimeters, if encountered on CT or MRI and up to 7 centimeters on ultrasound, don't require a follow-up. If the patient is postmenopausal, then that threshold is 3 or 5 centimeters, and that, this size range exists here because for In some cases, we don't think we fully assessed the lesion to be certain that it's a simple cyst. Um, and so, uh, it could be that we only imaged part of the lesion, didn't have the right sequence for it. Um, so in, in those cases, uh, a follow-up ultrasound in 6 to 12 months can be performed, um, to assess for stability and then also, uh, further characterize the lesion at that time. Um, if the patient is premenopausal, sometimes you can consider doing shorter interval follow-up at 2 to 6 months because in that patient population, we will be thinking that these are physiologic changes that would, uh, resolve over the next several menstrual cycles. Um, and so in those cases, the shorter follow-up would be to assess for resolution of the finding. Sometimes ovarian cysts or abdominal follicles can bleed or rupture, um, usually with ovulation. The, um, in most cases, the bleeding, uh, occurs within the cyst itself and is self-limiting. Um, and like bruises on your skin, turning all different colors of the rainbow before it goes away, hemorrhage on imaging also has a very varied appearance depending on the timing. The classic appearance on the ultrasound includes this reticulated or fishnet appearance. Uh, sometimes we see some Attract a clot, um, sticking to the sides of the wall. On CT hemorrhagic cysts will be hyperdense. Um, this one actually has a fluid, fluid level, that's also another good sign for hemorrhage on CT. Um, and on MRI it will be bright on a T1 weed sequence, um, just reflecting the blood or proteinaceous content of it. Uh. And uh If we see these features and we're confident that the lesion is a hemorrhagic cyst, we don't need to do any further action. If some of the features are not so typical or if the cyst is greater than 5 centimeters, then we want to recommend a follow-up ultrasound in 2 to 3 months just to ensure resolution. In a postmenopausal patient though, these uh findings are not expected. Again, they shouldn't be ovulating, they shouldn't be having hemorrhagic cysts. Um, and so in those cases, we need to do dedicated pelvic imaging, um, with or without gynecology. Endometriosis is the process for endometrial tissue implants and grows outside of the uterus. Um, endometrioma is when the endometrial tissue grows inside the ovary, sometimes called a chocolate cyst. Um, and sometimes the endometrioma can be difficult to distinguish from hemorrhagic cysts, uh, in which case, a short interval follow-up ultrasound may be recommended. So let me show you why. So here's an example. of an endometrioma on ultrasound. It is a cystic lesion with homogeneous low-level echoes inside and here's a hemorrhagic cyst. They look kind of similar, so sometimes it's not easy to tell. Um, and so we want to do that short interval follow-up because if it's a hemorrhagic cyst, it should go away with the next few cycles. Um, if it's an endometrioma, it will be having repeated bouts of bleeding inside and would persist over time. Um, Patients with endometrioma or endometriosis could benefit from gynecology evaluation, um, because the treatment options would include active surveillance or surgical resection. Other benign annexal lesions include mature teratoma or a dermoid cyst, which is a benign neoplasm arising from the primordial germ cells of the ovary. Um, they are characterized by different differentiated tissues from different elements, commonly including fat, calcification, sebum, sometimes teeth and hair. Um, patients with mature teratomas may benefit from a discussion about surgical resection. Para ovarian cysts are benign remnants of the Wolffian ducts. So on this top ultrasound image, I'm going to highlight the ovary in blue and then the yellow arrow is going to point to the cystic structure. It's clearly separate from the ovary. Um, seeing patient underwent CT, ovary in blue, paraovarian cyst in yellow. Um, so simple paraovarian cysts don't need any further evaluation. They have no risk of malignancy. Uh, sometimes we see a hydrosalpinx, which is basically a dilated fallopian tube. See the tubular appearance on both CT and MRI. Um, this is most commonly from tubal scarring and unless the patient is symptomatic or undergoing some gynecologic intervention, we don't need to do anything about this. Anything that does not fit this def uh these definitely benign categories requires further evaluation, and we have a new risk stratification system called ORADS, uh, or ovarian and Nexal reporting and data system. Again, it stratifies the lesions on the spectrum of the. Benign to malignant based on the imaging features. So our pelvic ultrasound and pelvic MRI reports will have these ORAD scores where appropriate, um, and the ORAD score then specifies what we should be doing next, which should also be included in your report. Um, and then the next steps could include further imaging, gynecology, or gyne oncology consult. To recap, um, uh, many ovarian lesions or nexal lesions are benign. In the premenopausal patient, they're most likely going to be related to normal physiology, um, but in a postmenopausal patient, that is not expected, so we wanna be a little bit more cautious. Um. And, um, ultrasound or MRI would be the preferred uh modality for characterizing ovarian lesions. Um, some lesions may require a follow-up ultrasound either to confirm resolution if we think it's a physiologic change or for active surveillance for its entities such as endometrioma or dermoid cyst. Um, if the lesion is suspicious or very large or it's an unexpected finding in a postmenopausal patient, then we do wanna work them up further with a pelvic ultrasound or MRI. So in conclusion, we found, we talked about a lot of different incidental omma and they are very common, and many, if not most, are all benign. Um, generally, if it's less than 1 centimeter, they're too small, uh, likely insignificant. Leave them alone except for the subcentimeter enhancing, uh, renal lesions. And if at any point, uh, the lesion is not completely benign and uh greater than 1 centimeter, then we might need to do further imaging uh that's really tailored to the problem at hand. Um, and in some cases, we might want to do follow-up and give that little bit of a time interval to our advantage, um, and image them in 6 to 12 months.
