Sonography of Soft Tissue - HD

Sonography of Soft Tissue Masses

Hi, I'm Dr. Cheryl Curvy from Einstein Medical Center in Philadelphia, Pennsylvania, and I am going to speak about sonography of soft tissue.

Yes, you heard me correctly. We're gonna discuss soft tissue umps, actually things that rhyme with ump. We're gonna talk about bumps and lumps and even humps. Unlike I gore, who didn't even realize that he had this large hump on him.

We scanned people with ultrasound with tiny soft tissue masses like the suspected gloma tumor, which measures less than two millimeters of the pad of someone's thumb. Any new enlarging or symptomatic mass needs to be evaluated. Ultrasound is useful in differentiating solid from cystic masses, and as we know, it's dynamic, affordable, portable, and lacks ionizing radiation.

Learning Objectives

Our learning objectives are multiple, and I'm not going to go through them. We're gonna tackle them as we go.

I have no conflicts to disclose.

Etiologies of Soft Tissue Lumps

The etiologies for soft tissue lumps is also multiple. This is a huge topic. I will touch upon many of these entities, but unfortunately I do not have time to go through each and every one. But this will give us a flavor and a touch of this huge topic.

Systematic Approach to Soft Tissue Masses

When I approach someone with a soft tissue mass, I think about the systematic approach. I wanna know the four W's, the clinical history and physical exam.

Who is the patient? How old are they? Where is the lump, the anatomic site? Is it superficial? Is it deep? Is it in the extremity? Is it around the joint? When did they first notice the growth? What's the growth pattern? Does the mass fluctuate in size? And why might they have this growth? Is there prior trauma or surgery or a history of malignant cancer?

Ultrasound Technique

Ultrasound technique? The transducer we use varies depending on the depth of the lesion. We wanna use the highest resolution transducer that will see the necessary depth. So if I'm looking at something very superficial like the fingers, I can use a 12 or 17 megahertz to see very superficially or a very high resolution transducer that does not need much depth.

I'm gonna use ample gel and a light touch because I don't wanna compress the lesions. I'll use harmonics and compound imaging to see fluid structures as well as to better evaluate the borders of the lesions, color and power doppler and occasionally pulse doppler is used and extended field of view imaging in large lesions.

Non-Neoplastic Masses

I've separated the non neoplastic masses into large categories, benign cysts, infectious etiologies, traumatic reactive, pseudo tumors, and vascular etiologies.

Benign Cysts: Cystic Bumps

So let's start with cystic bumps. We're gonna start with a ganglion cyst. It's a muco mucor material surrounded by fibrous tissue. Common, especially among young women. Location is most common in the hand or wrist, but can't be seen in the foot and ankle in the wrist. The most common location is at the dorsum of the wrist, specifically at the region of the proximal radiocarpal joint. At the scapholunate ligament region symptoms, patient may have pain or a palpable mass.

Here we see an anechoic structure located near the flexor tendon. This is someone with a ganglion cyst on ultrasound. They're well-defined anechoic or hypoechoic areas with through transmission. Even though they are benign, they are non-compressible. This is actually helpful in distinguishing them from fluid. In a joint recess, smaller ganglions may have internal echoes, whereas larger ones are anechoic with multiple loculations.

A ruptured ganglion can be confused for a solid mass, but knowing their typical location and typically seeing a small amount of fluid within will help with the differential.

Synovial Cyst: Popliteal Cyst

The Baker's, a synovial cyst. A popliteal cyst is the most common of the synovial cyst. It's located between the semimembranosus and gastrocnemius tendons along the medial side of the popliteal fossa. Their appearance is anechoic or hypoechoic and they may contain loose bodies.

When I look at these entities or when I'm shown an image of a ganglion cyst, I wanna make sure that I can see this hook here as it comes between the semimembranosus and gastrocnemius tendons. I always ask my sonographers, where's it located? Where are they seeing the cystic lesion? Because there are other etiologies for cystic lesions around the knee. So I wanna make sure it's posterior medially and I wanna see this hook area.

Patients are frequently asymptomatic and they're found incidentally in many studies for deep venous thrombosis. However, when they rupture, they can cause pain and swelling and therefore are a major differential diagnosis for patients with deep venous thrombosis.

Acromioclavicular Joint Cyst

This is an 83-year-old man with a non-tender shoulder lump, which was spontaneously fluctuating in size. What we see is a cystic lesion with a few internal echoes. Of note is that this cystic lesion is in close proximity to the left acromioclavicular joint. Here we see the border of the joint is irregular. There's some spurring. This is someone with osteoarthritis.

When we see fluid collections near joints, we wanna think about their causes. So this acromioclavicular joint cyst is associated with longstanding rotator cuff tear. The theory is that there's chronic friction caused by a high riding humeral head, which causes mechanical wear of the articular cartilage of the AC joint. This allows fluid to pass from the glenohumeral joint superiorly into the acromioclavicular joint accounting for an AC joint cyst. This is called the geyser sign.

So we took a look in this patient to look at his rotator cuff and he does have a rotator cuff tear. Let's look at a normal first for comparison. Here we can see the subcutaneous fat, the deltoid muscle, and the rotator cuff. Note the smooth cortex. This is a normal, here's our patient subcutaneous tissue deltoid muscle, and the rotator cuff is torn that you do not even see it. What we see is irregularity along the cortex. This is someone with a rotator cuff tear.

So remember, cysts near joints. Think about their causes. If I had a cyst along the periphery of the knee, this may be related to a meniscal cyst. If I have a cyst in the region of the spinoglenoid notch of the shoulder while I'm doing my ultrasound, I'll think about a labral tear. And it's important to think about these locations because drainage of the cyst may not rid us of the problem because they may just recur.

Inflamed Bursa

Another cause for fluid around the joints are inflamed bursa. Bursa are located between the bones and the tendons or muscles around the joint. Normal ultrasound of a bursa is a hypoechoic cleft. However, when they become inflamed, they fill with fluid. The fluid may be anechoic or hypoechoic as we see here in this patient with iliopsoas bursitis.

Here we have fine level echoes within a distended bursa, as well as thickening of the synovium. We may or may not see hyper vascularity. Note that ultrasound cannot distinguish infected from non-infected etiologies. And if there is concern for infection, then aspiration is required.

Epidermal Cyst

An epidermal cyst is the most common cutaneous cyst. They can occur anywhere on the body, usually in areas with hair. They are caused by displaced surface epithelial cells that outline cyst filled with keratin and liquid debris. They are well encapsulated hypoechoic masses with internal echoes and usually with through transmission. They may create the pseudotestes sign as we see here. Also, we may see concentric rings as we see here. The difference between these two is the degree of hydration within the cyst.

Tenosynovitis

This is a patient who presented with a wrist lump for eight months. We see this bump on x-ray. I'm thinking it's gonna be a ganglion. Right? So we do the ultrasound and what do we see? Well, we do see fluid, but it's not a ganglion cyst. On transverse imaging, you can see that the fluid is surrounding these echogenic areas. On sagittal imaging, we see the typical fibular pattern of a tendon. So this represents fluid surrounding a tendon and this is tenosynovitis inflammation of the tendon sheath.

Around the tendon ultrasound appearance. We may see fluid either anechoic or hypoechoic fluid distending the sheath as we see in this patient. Or we may see thickening of the tendon sheath.

This is a 60-year-old female with left arm pain and swelling. She came to rule out a deep venous thrombosis. There was no deep venous thrombosis, but my sonographer talked to the patient, saw where she was swollen, where she had pain and scanned that area. What we see on this transverse image is fluid surrounding multiple tendons. On longitudinal image, we see the fluid, the tendon, and then we see more hypoechoic material on color doppler imaging. There is hyper vascularity within this area and this also represented tenosynovitis. But in this patient it wasn't infected tenosynovitis, which we concluded by after aspiration. This grew out staph aureus.

Infectious Etiologies: Soft Tissue Infection

This is a good segue into our next category, which is soft tissue infection. Note our lump cellulitis.

Cellulitis is an acute bacterial infection of the dermis and subcutaneous tissues. It is a clinical diagnosis. It is frequently associated with skin wounds or ulcers or skin disease. On ultrasound, we may see increased echogenicity with sound attenuation As we see in this area. Here's a more normal looking subcutaneous fat. And look. Here in the region of cellulitis we see increased echogenicity. A closeup of this area sure shows the blurred fascial planes and relative sound attenuation. We really are not seeing deep into the fascial planes.

Another appearance is to see hypoechoic material outlining the fat lobules as we would in non-infectious pulmonary edema. This is an early appearance. This is a more chronic appearance of the same etiology. Note how the fat globules are somewhat compressed. We may or may not see hyper vascularity.

Why do ultrasound in patients with cellulitis? The reason to do it is to exclude this entity, exclude an abscess because the two are treated differently. Abscesses are drained in addition to being treated with antibiotics.

So abscesses are walled off collections of necrotic tissue in inflammatory cells and bacteria. Their appearance on ultrasound is variable. We see liquified contents, which can range from anechoic to hyperechoic. The margin of an abscess may be sharp or ill-defined. Posterior acoustic enhancement is also variable depending on the degree of echogenicity within the fluid as well as its comparison with the adjacent tissues. We may or may not see gas as we do in this patient seeing fine focal echogenic areas with slight posterior shadowing representing gas foci.

We look for the ultrasound fluctuation sign, which is compression of the fluid to look for movement of the internal echoes, which I'll show you later. Color and power doppler is helpful in distinguishing inflammatory and infectious collections from non-inflammatory, but again, does not cannot definitively determine whether something's infected. Doppler of deep masses is limited secondary to their depth from the transducer.

Another reason to do an ultrasound in someone who has an abscess is to look for a cause. Maybe there's a retained sponge. Maybe we can see a bullet as we see in this patient. Next to this infected fluid collection.

This is a man who came in with right arm pain and fever. What we see is this ill-defined hypoechoic area interdigitating between the fat planes look on a closer view image. Here again, we see hypoechoic material with fine level echoes interdigitating between the fat planes. There is hyper vascularity on color doppler imaging. This was read as a phlegmon no drainable collection. This is not, this was an abscess.

I found that in soft tissues abscesses frequently occur as ill-defined fluid collections. That course longitudinally through the fatty fascial planes. So again, abscesses are not necessarily always well-defined focal collections they may drain through the fascial planes.

Thus causes of missed soft tissue abscesses or ill-defined fluid collections like we've discussed someone with very echogenic purulent material deep locations. Don't forget, let's say you're looking at the thigh and you may just use a linear transducer to look superficially. You might also wanna switch to a lower frequency transducer to see deeper and the tissues don't miss the fluid that might be deeper than the subcutaneous fat. Also look in hidden locations, ask the patient where they hurt the most specifically beneath the scrotum. That's an area that's frequently missed in my experience.

We talked about the ultrasound fluctuation sign. And let me show you. Here's an area the same fluid collection. We're compressing it. You can see the material moving as we compress the fluid. So this is not just inflammatory material. This is actually infected fluid.

The next patient is a 60-year-old diabetic presenting with fever and thigh swelling. At first look we might see the patient has cellulitis, right? There's blurring and poor definition of the fascial plane, especially deep in the tissues. Same patient in another area. We see fluid interdigitating between the fat lobules. And let's look at this image also. Same patient. The subcutaneous tissues here don't look too bad, but look deep in the fluid. Deep in the subcutaneous tissues we see fluid. Here's the bone that's creating this echogenic area with dense shadow, but this is not bone. This is increased echogenicity with hazy shadowing. This is someone with gas in the soft tissues and this is someone with necrotizing fasciitis or necrotizing soft tissue infection.

It's a rapidly progressive bacterial infection of the subcutaneous tissues and fascia. Patients are frequently diabetic immunocompromised or severely ill. This may have a fatal course and requires prompt treatment with surgical debridement and antibiotics.

It's ultrasound appearance. It may just look, it may be confusing and mimic cellulitis early on, but look for fascial thickening and look for fluid deep in the fascia like we saw in that patient. Deep fluid measuring greater than four millimeters is highly sensitive. And specific for this diagnosis, sensitivity of 88%, specificity of 93% look for gas in the soft tissues, which we saw also in this patient, which was advanced disease.

This is the same patient I just showed you. This is a CT scan obtained afterward we see the stranding in the subcutaneous fat, but in addition, we can see thickening of the fascia and also gas along the fascia layers and even deeper, this is necrotizing fasciitis.

Post-Traumatic Lumps

Let's jump to the next category of post-traumatic lumps.

Intramuscular Hematomas

Im intramuscular hematomas have a variable appearance on ultrasound acutely they may appear hyperechoic as we see in this patient. And this is actually the same patient over here to the right lower, just a little while a week later where you can see liquefaction of the intramuscular hematoma. Also, sometimes we see a fluid hematocrit level. The echogenic ones are the difficult ones to see. So if you have someone who's had trauma and you're worried about possible hematoma, look carefully in the muscle. You should see that there's loss of the normal striation pattern of the muscle. And here's the hematoma, increased echogenicity, but sometimes they might be isoechoic. So be careful.

This is a patient status post motor vehicle accident five weeks before with an enlarging right thigh mass. Note that the patient had 400 ccs of fluid drained three weeks ago. Here's the ultrasound. The subcutaneous fat actually looks okay, but we do see a fluid collection deep within the subcutaneous fat actually near the fascial layer on a curve. You could see that this collection is actually sizable. It does appear to come close to the skin surface, but that's because it was drained. Here's an MRI showing this fluid collection and the fluid is located deep within the subcutaneous fat. This represents a closed degloving injury. Morel-Lavallée.

Let's look at the anatomy. The deep fascia encases the muscles. It separates the muscle from the subcutaneous fat. There are vessels and lymphatics that perforate through this area. When we have a severe trauma such as a motor vehicle collision or I've even had a lady who slid downstairs. When we have that trauma that causes a shear injury, you get separation of the subcutaneous fat from the deep fascia accounting for and causing fluid collection. In this region, the fluid is composed of blood and lymph fluid.

These typically are located in the region of the hip, particularly near the greater trochanter and upper thigh. But they have been described in football players near the knee. Treatment depends on the chronicity and size of the lesion, Including compression bandages with needle aspiration to surgical debridement.

On ultrasound, they appear hypoechoic or anechoic and are usually compressible. One may see fatty remnants as we see here in this patient. And here's the same corresponding ct. Acute and subacute lesions are usually heterogeneous with irregular margins. While more chronic lesions are more homogeneous and flat or fusiform in shape with a well-defined margin, chronic lesions. In some chronic lesions, you may see a pseudocapsule, which is important and assists the surgeon in treatment.

Muscle Hernia

This is a case of a 57-year-old runner who noticed a small bump on her anterior shin. This corresponds to the area of the bump on real time imaging. We could see that this lump actually represents muscle that's projecting through a defect in the fascia. This is someone with a muscle hernia through the anterior fascia.

This typically occurs on the anterior portion of the shin affecting the tibialis anterior and may be caused by trauma or just areas of fascial weakness such as here where we see a perforating vessel. And right next to it we have this little lump ultrasound technique requires gentle touch and abundant gel. You can see we use lots of gel in this patient. Why do we wanna do that? We don't wanna compress the lesion. We actually wanna be able to see it. We're gonna look for the fascial defect, Which is, here's the fascia, this echogenic line. And you can see the defect in the fascia with the muscle projecting through the muscle is frequently hypoechoic and has a mushroom type of appearance.

Bony Etiology: Stress Fracture

Sometimes people come to us and the cause of the bump is actually bony in etiology. I've seen people with exostosis or spurs that have called lumps and bumps. But in this patient she, this woman pointed right to this area where there is cortical discontinuity. And along the side I can see some callus formation and sure enough, this is someone who had a stress fracture. This is a woman who walked over two hours every day.

Non-Infectious Reactive or Inflammatory Masses

The next category is non-infectious reactive or inflammatory masses.

Abdominal Wall Endometriosis

Here we see a woman who has a hypoechoic mass within the adipose tissue that's actually involving the underlying muscle on color doppler imaging. There is some flow within the structure. The structure is hypoechoic but heterogeneous with areas of slight sound attenuation.

This is a case where the four W's. That systematic approach is really very helpful. We wanna know what her story is. Has she had prior trauma? Where exactly is the location of this mass and her area of pain? Well this is a painful mass under a cesarean delivery scar. This is someone with abdominal wall endometrial implant abdominal wall endometriosis present, frequently present as a palpable lump and pain. The pain may be classically cyclic but can also be constant. And the palpable findings and pain is in the region of the cesarean scar.

Ultrasound is usually the initial imaging modality to look at women with painful pelvis. So we need to think carefully about this diagnosis. Why? Because the transducer that we use is important. Typically we scan the patients initially with a curved five to one megahertz transducer to just get an overall view of the pelvis and to look deep into the pelvis. So this abnormality occurs within the deep subcutaneous fat muscle and fascial layers in the anterior abdominal wall. If we're looking deep with a curved transducer, we might actually miss this entity.

And then you say, no problem. We use a higher frequency transducer when we do our endovaginal exam. However, now we're scanning endovaginally and the area of interest is really far away and we may not see it. So I recommend use of a high frequency linear transducer such as the nine megahertz, which should see deeper in the muscle. So we can see these lesions in a very thin patient. You may see it with a 12 and obviously in a heavier patient you'll have to go to a lower frequency transducer to see deep enough their appearance. They're usually round or oval, primarily hypoechoic, but maybe somewhat heterogeneous like we saw. The larger the lesion, the more irregular the margin and increased vascularity on color doppler imaging. They may or may not have small cystic areas that represent pooling of blood.

Here we see in this patient, this is the lesion. It's somewhat heterogeneous, right? It's hypo to isoechoic but does have this area fluid on MRI. The same lesion shows increased signal intensity on T one weighting, which persisted despite fat saturation. And this represented abdominal wall endometriosis.

Traumatic Neuromas

Next are traumatic neuromas. They are a disorganized attempt at nerve regeneration. This is a patient this upper image is a patient who had a self-inflicted wound to his wrist. Here's the area of scarring. He was coming in years later with paresthesias to the median nerve distribution. And here we see the typical fascicles of the median nerve, but they go into this hypoechoic mass. This is a traumatic neuroma, a disorganized attempt at nerve regeneration.

We can also see them in patients post amputation. And here's the other lump to remind me. Yes, the stump here is a terminal or a traumatic neuroma caused by the amputation. Note. This is, we see that typical yo-yo sign described On ultrasound again, we see a hypoechoic mass. The ultrasound in this patient with the amputation confirmed that this was truly a symptomatic neuroma.

Peripheral Nerve Sheath Tumor

Next patient is a 57-year-old man with a left forearm mass. So within the muscles of his forearm we see this hypoechoic mass. We know it's soft tissue 'cause we see color flow on color doppler imaging on sagittal imaging. However, we see that it's not originating from the muscle fibers, it's actually causing a split fat sign. So this is actually within one of the fascial planes in the muscle. It would be the equivalent of being located here on the transverse image. What we see is we see a hypoechoic mass. Again, we have flow within this mass, but note that there is typical nerve fascicles extending to this mass and exiting the area. So this is someone with a peripheral nerve sheath tumor. This happened to be a schwannoma.

Differentiating schwannomas from neurofibromas can be difficult. There are some clues. Schwannomas tend to be round and hypoechoic and are typically more hypervascular on color doppler imaging than neurofibromas. Also schwannomas, although they may be eccentrically located, are frequently commonly stop Good. Although they may be concentric in location. We look for an eccentric location like we see on this MR in this these two schwannomas, which the ultrasound corresponds.

What's important is that schwannomas actually can be shelled out, whereas neurofibromas for treatment need to be resected with nerve grafting. Neurofibromas are more fusiform. You may see a target sign and typically less hypervascular. Both can have cystic changes.

Soft Tissue Tumors: WHO Classification

The World Health Organization has classified soft tissue tumors into nine categories. And we don't have time to discuss all of these, but I wanted to make you aware of them. Note also that the nerve sheath tumors are not included in these categories.

Adipocytic Category: Lipoma vs. Liposarcoma

But first we're gonna talk about an entity in the adipocytic portion, adipocytic category. And let's look at this patient. This is a 45-year-old female with a back mass. She has an elliptical mass that's compressible. The echogenicity is similar to the adjacent subcutaneous fat and it is avascular. Here's a color Doppler image to the right. There's no flow seen in that structure. This represents a lipoma easy, right?

Well there was a study in 1991 looking at ultrasound characteristics of lipomas. And they saw that they actually can be quite variable. The size may vary from small to large. In general, their shape was consistent. They were usually oval with their greatest dimension parallel to the skin. The borders, however varied from well-defined to poorly defined. And the echogenicity also varied from hypoechoic, isoechoic hypoechoic or mixed.

In 2004, the group from Michigan took a look at the same topic looking at soft tissue lipomas and the accuracy of sonography in diagnosing these lesions. And they did a retrospective evaluation of surgically proven soft tissue masses with 25 lipomas and 14 non-lipomas. Now they realized there was a bias because the people that they were imaging had had surgery to remove it. But despite that, the sensitivities were quite low for diagnosing soft tissue lipomas and our accuracies were low.

So does this mean that ultrasound should not be performed if a lipoma is suspected? Well, let's look at a study by Kransdorf, et al. They looked at the distinction of lipoma and well differentiated liposarcoma. They found significant imaging or clinical features which favored liposarcomas. And although this study was performed with CT MRI, as I said in my residents, pathology is pathology. And whether we're looking at different modality, we're still looking at the same pathology.

So they found the following features concerning for liposarcoma, a large lesion greater than 10 centimeters. A lesion with thick septa equal or greater to two millimeters or focal thickening of a septum, globular, and or nodular non adipose areas were 32 times more likely seen In liposarcomas, a mass with less than 75% fat was concerning. And fatty tumors in men, especially older men, 13 times more likely. Other suggestive findings that were not proven clinically significant are the presence of calcification, which were seen more commonly three times more commonly in a liposarcoma than a lipoma.

They only had four patients with a lipoma who had received injection. So they did not have enough patients to assess for clinical significance. But they noticed that there was no enhancement in the four patients with lipomas. The most reliable feature for lipoma was that it was completely composed of fat.

So my recommendation is that we can be reasonably confident. We have a diagnosis of a lipoma. If we see a superficial soft tissue mass completely composed of fat. If there are other suspicious features, then MRI or CT is recommended.

Oh, here's a fatty tumor. And you're saying to yourself, is she showing me another lipoma? No I'm not. I'm actually showing you a fat containing hernia. So don't forget, when you're looking at fatty masses, look deep to make sure you're not seeing a hernia. And here you can see the fascial defect.

Fibrohistiocytic Category: Giant Cell Tumor of the Tendon Sheath

Another category of the World Health Organization is the fibrohistiocytic category. And this entity, giant cell tumor of the tendon sheath is located within that category. This is a benign entity that is localized nodular tenosynovitis histologically. It's the same as pigmented villonodular synovitis.

This entity arises from the tendon sheath as it is nodular tenosynovitis. Its location, it's common in the hand, particularly the first through third fingers, but it can also be seen in the toes typically occurs in 30 to 50 year olds, female more than men, and presents as a slow growing mass with or without pain.

Here we have an x-ray showing a soft tissue lump along the periphery as well as along the palmar aspect of the finger. The second finger on ultrasound, they're typically hypoechoic. Most are homogeneous or have some degree of vascularity on doppler imaging. We may or may not see bone erosion, which we did not see in this patient. And we should look for a tumor encasement.

So here's a mass. Here's the, on this ultrasound we see the tendon, we see this hypoechoic mass and on real time imaging, note how it encases the tendon. Here's the tendon. We start to see the mass, the mass, the mass, the mass. It's really encasing coming around this tendon. And this has importance and this is a reason to scan these entities to help the surgeon in their resection. Since treatment is excision, there is a 10 to 20% recurrence rate.

Vascular Etiologies

The next category is, this is my clue to the next category lump. Wait a minute, that's not, how did that picture get there? That's not the lump. I mean this lump. Yes, I'm looking at vascular etiologies as causes for soft tissue masses.

Hemangioma

Hemangioma, whether it, the nomenclature is somewhat confusing for hemangioma. There are some people who include hemangioma in the tumor of infancy and also use this general term to include malformations, which are just tortuous vessels. But we are not gonna do that. We're gonna use hemangioma to refer to the common tumor that proliferates in infancy and usually regresses in childhood by age five, but can be seen at any age. Their benign soft tissue tumors. They may or may not present with pain and their size may fluctuate on ultrasound. They're typically compressible, they may be hypo or hypoechoic and one sees hyper vascularity.

Let's look at this case courtesy of Dr. Middleton. We have a focal hypoechoic mass that on color doppler imaging has incredible high vessel density with high velocities on pulse doppler imaging.

Vascular Malformations

We're gonna contrast this with vascular malformations. Vascular malformations are abnormal vascular structures. They're defined by their flow. High flow has prominent arterial flow and slow flow. We see venous flow. It is a slow flow lesions which have the phleboliths 15% of the time.

Here's an example. In an 18-year-old woman with prominent vessels intramuscular within a muscle in her calf on color doppler imaging, we have color flow and we see venous flow. This is a slow flow vascular malformation. This is the same patient where we can see phleboliths on x-ray.

Superficial Fibromatosis

The next topic is superficial fibromatosis. Superficial fibromatosis is part of the fibroblastic World Health Organization category and refers to benign fibrous proliferation. The diagnosis of these entities is based on clinical appearance and location, location, location. They are slow growing but they have an intermediate behavior. So although they are benign, they may invade deeper into the structures and that's why ultrasound is helpful.

So here's an example of a plantar fibroma. This is located in its classic location, which is along the medial aspect along the plantar surface of the midfoot. And here we see the plantar aponeurosis extending toward this lesion. These masses are in close proximity to the plantar aponeurosis. They may or may not have color flow on color doppler imaging.

Here's another example of a palmar or Dupuytren's fibroma. And this is located in the region of the palmar aponeurosis which is located between the skin and the flexor tendon. They all appear hypoechoic, but they may or may not have mixed echogenicity reflecting their intermediate behavior. There is a high recurrence rate between 20 to 50%.

Malignant Soft Tissue Tumors

Malignant soft tissues. Phew, we've gone through a lot, huh? Malignant soft tissues. Primary or metastatic account for less than 1% of all neoplasms. The sarcomas are the most common primary soft tissue malignancy.

Ultrasound can be used to monitor tumor stability or recurrence and especially if there's orthopedic hardware. Well, their appearance on ultrasound is nonspecific. They're usually hypoechoic. They're often hypervascular. They may or may not have anechoic areas from tumor necrosis. You may see hyperechoic foci of calcification or ossifications. The margins may vary being well-defined or ill-defined and they are homogeneous or heterogeneous.

So here's my recommendation. If you scan someone and we can put it into the classic, the benign appearing entities that we just discussed, that's fine. And, but if it's indeterminate and you're not sure, then we need further evaluation like this patient. This patient came in with a palpable lump behind her knee if she came in to assess for a popliteal cyst. But what we saw was a large soft tissue mass, heterogeneous soft tissue mass. There was flow on color and pulse doppler imaging, we obtained an MRI and what we see is this lobulated soft tissue mass with heterogeneous enhancement. And this was a malignant liposarcoma.

Conclusion

Conclusion, ultrasound should be used as an initial imaging modality for soft tissue masses, especially in the extremities. The use of ultrasound and a systemic approach allows confident diagnosis of many benign soft tissue lumps. And here we went through them right here are the different etiologies.

Major points. Use compression techniques to distinguish complex fluid from solid masses. Don't miss soft tissue abscesses. Remember they can be ill-defined echogenic or look for the deep ones. Change you may have to change your transducer. Recall the importance of deep fascial fluid collections. If you have someone with infection and you see deep fascial fluid, then be concerned. There may be necrotizing fasciitis or a necrotizing soft tissue infection. If you have someone post-trauma and you see deep fascial fluid, you may have shearing degloving injury. The Morel-Lavallée. Recall the useful characteristics in distinguishing lipoma from liposarcoma. Ultrasound is limited for visualizing deeper structures and does not penetrate through air or bone.

So I'd like to say thank you for listening. Bye-bye.