I. Extrahepatic growing hepatocellular carcinoma
Extrahepatic growing hepatocellular carcinoma (eg-hcc) is a type of hepatocellular carcinoma that grows outside the liver.
It is mostly seen in adults, with a peak in the age of 50-60 years. It is more common in men than women.
The maximum transverse diameter of the extrahepatic part of the exophytic growing hepatocellular carcinoma should be larger than the intrahepatic part, as a way to distinguish it from the common giant hepatocellular carcinoma.
Subtypes.
Tilted type
The tumor is located completely outside the liver and receives nutrition from the liver through the tumor tip. It can invade surrounding tissues and organs and establish new blood circulation with surrounding tissues.
Prominent type
The tumor is mainly protruding outside the liver, but a small part of it is still located inside the liver, and it can also invade the surrounding tissues and organs.
The tumor can also invade the surrounding tissues and organs. The tipped type is rare, while the herniated type is relatively common.
Imaging Performance
The imaging presentation is the same as that of common hepatocellular carcinoma.
It must be differentiated from retroperitoneal tumor and gastrointestinal tumor.
The diagnosis can be suggested by the detection of portal vein cancer thrombus.
Some of the exophytic hepatocellular carcinoma is due to extrahepatic malignant transformation of cirrhotic regenerative nodules, therefore, the detection of cirrhotic base and intrahepatic subfoci can suggest the diagnosis.
2.Fibrolamellar carcinoma
It is often seen in the left lobe, and is often a single lobulated lesion with a hard texture, swelling growth, clearly demarcated from normal liver tissue, and may have an envelope, with a giant type, usually larger than 10 cm in diameter.
A stellate fibrous scar in the center of the tumor radiating to the periphery and separating the tumor is an important feature.
Another feature is that the central scar may have speckled calcification.
Microscopically, the tumor cells are polygonal with eosinophilic staining and large fine running nuclei. There are more fibrous stromal components, sometimes arranged more neatly, dividing the tumor cells into strips or clusters, which are characteristic.
Fibrous lamellar hepatocellular carcinoma is a rare type of hepatocellular carcinoma, accounting for only 1%-2% of the total incidence. The incidence rate is similar in men and women, with a predilection for adolescents, and the proportion of patients under 35 years old is 15%-40%.
Clinical symptoms are not characteristic, mainly abdominal mass and upper abdominal discomfort. The vast majority of patients have no cirrhotic base, few hbv infections, and are mostly negative for afp.
Although fl-hcc is a large mass, it has a high surgical resection rate and a good prognosis. Even if the mass recurs after surgery, it can be resected again, and the postoperative survival is 32-68 months, or even higher.
Imaging performance
1.CT performance
The plain scan is a low-density mass shadow with clear margins and may be lobulated. The central scar shows a clear border of stellate or irregular lower density shadow, and speckled calcification is visible.
The tumor parenchyma in the arterial stage is uniform or diffusely enhanced at an early stage, while in the portal stage, the tumor parenchyma fades quickly and is less dense than the surrounding liver tissue.
The central scar is mostly without clear enhancement in the arterial and portal vein stages. A minority of 25% fhcc showed enhancement in the delayed phase. This is due to the interstitial component of the blood vessels within these few central scars.
The rate of lymph node metastasis in the hilar region of the liver is higher than that of common type hepatocellular carcinoma.
2.mr seen
Tumor t1wi is low signal in 86%, iso-signal in 14%, and uniform signal in 80% of cases; tumor signal on t2wi is not uniform, mostly high signal.
The central scar, which is basically low signal on all sequences, is an important differentiator; however, there are still a few cases with high signal. (central scar similar to fnh – high signal on t2wi)
Differential diagnosis
Fibrous scarring can be seen in common hepatocellular carcinoma, but is generally small in number, rare with calcification, and often clinically associated with cirrhosis and elevated afp
hepatic cavernous hemangioma is seen in the arterial phase with early mass or dot enhancement at the margins and spread from the periphery to the center, with slow fading of enhancement within the tumor in the extended phase, and isointense or slightly denser than the surrounding liver tissue
Hepatocellular adenoma is often a single round lesion with peritumoral and intratumoral hemorrhage, uniformly enhancing in the arterial phase and isointense or hypointense in the portal phase, with clinical features of young female patients, some with a history of long-term oral contraceptive use.
There is no obvious specificity of fl-hcc on ct images, but in young and non-cirrhotic patients, if a large intrahepatic mass is found, the possibility of fl-hcc should be considered after excluding cavernous hemangioma, but care should be taken to differentiate it from focal nodular hyperplasia (fnh).
III. focal nodular hyperplasia (fnh)
fnh clinical features: focal nodular hyperplasia of the liver is a benign regenerative nodule of hepatocytes and is a tumor-like lesion. It is mostly seen in young and middle-aged women. It is usually asymptomatic clinically and is found mostly incidentally.
Pathologic features of fnh: fnh is a polycythematous substantial mass with a homogeneous internal structure and rare hemorrhage and necrosis. fnh consists of hepatocytes normally arranged in nodules, fibrous septa, proliferating bile ducts, infiltrating inflammatory cells, and blood vessels. It is characterized by a stellate scar and radial fibrous separation in the center of the lesion and thick-walled blood supplying arteries within the scar.
Intratumoral hemorrhage, necrosis, and infarction are rare, unlike hepatocellular adenomas. fnh is more common than hepatic adenomas, about twice as common, and is not associated with oral contraceptives. Approximately 80-95% are solitary.
Imaging manifestations
1. ct manifestations.
Plain scan: Most of them are isolated isointense or slightly hypointense masses with clear boundaries and uniform density, rarely with calcification. In a few cases, a low-density scar is seen in the lesion. When the mass is isointense, it only shows the occupancy effect or the central hypointense scar.
Enhancement: ①Tumor enhancement features: early masses show rapid and obvious homogeneous enhancement (arterial phase and early portal phase), and rapid contrast withdrawal in late portal phase or delayed scan is seen as isointensity. This enhancement feature is due to the rich arterial blood supply and large draining veins and blood sinuses in fnh. (ii) Peritumor vascular shadow: on late portal vein and delayed scan images, vascular shadow is seen around the fnh, which is associated with enlarged vessels and blood sinuses around the tumor. (iii) Thickened blood supply arteries: It is thought that fnh is a congenital vascular malformation with increased arterial perfusion leading to hepatocyte hyperplasia. Spiral CT scans in the arterial phase often show abnormal arteries. (iv) Scar and segregation: some can show scar tissue, which is hypointense on plain scan, and on enhanced scan in the arterial phase, the blood supplying artery can be shown within the scar, and on portal and delayed scans the scar can be seen to gradually intensify to equal or high density. Sometimes the enhancement can show radial fiber separation.
2.mr performance
mri plain scan: t1wi and t2wi can show four conditions
(1) both are isosignal (typical); (2) relatively low signal and high signal; (3) isosignal and relatively high signal; (4) relatively low signal and isosignal.
Central or eccentric scar is low signal and high signal on t1wi and t2wi, respectively, in typical cases, and may show low signal on t2wi in atypical cases, etc.
3. pseudo-envelope of fnh
There is no fibrous envelope in fnh, but there is a pseudo-envelope.
Composition of pseudo-envelope.
fnh compression of the surrounding normal liver parenchyma.
Peripheral vessels.
Inflammatory response.
Since the pseudo-envelope of fnh is compression of surrounding normal tissue as well as some perifocal vascularity and inflammatory infiltration, it is high signal on t2 (characteristic) and may have delayed enhancement.
The pseudo-envelope of hcc is mainly fibrous component is low signal on t1, t2, and shows continuous enhancement in the delayed phase of enhancement scan.
Differential diagnosis of flhcc and fnh
1, fnh usually occurs in young and middle-aged women
2. fnh lesions rarely exceed 5 cm
3, fnh calcification is rare, with less than 2% reported in the literature
4, Differences in central scar signal and strengthening performance
5.Difference in envelope signal
Hepatocellular adenoma (hepatic adenoma)
Etiology and pathogenesis
Hepatocellular adenoma (hepatic adenoma) is a disease that occurs in young women of childbearing age.
If anabolic steroids are not used, it will not occur in men.
Oral contraceptives and anabolic steroids increase the risk of development.
Pregnancy may accelerate the growth of the tumor and lead to rupture.
Another risk factor is in patients with glycogen accumulation disorder, which is often multiple and prone to malignancy.
Liver adenomatosis.
Pathological features.
70% to 80% of adenomas are solitary, but multiple cases are not uncommon. Patients with type 2 glycogen accumulation disease often have multiple adenomas and are prone to malignancy.
Gross pathology – well-defined, soft, grayish or yellowish-brown nodules often stained with bile.
Histology resembles normal hepatocytes, large in size, rich in fat and glycogen, with fatty deposits visible both inside and outside the cells, with enlarged blood sinuses at cellular intervals, supplied by arteries, lacking portal vein supply, and rich in blood supply. They lack connective tissue, have no central scars, bleed easily, and have a tendency to become malignant. Adenoma and highly differentiated hcc have similar pathological manifestations, and sometimes histological differentiation is difficult.
There is no central vein, confluent area, or lack of small biliary structures within the tumor – which can be differentiated from fnh.
kupffer cells are seen within the adenoma, but are few in number and poorly functional.
Adenomas may or may not have an envelope.
Adenoma cells are large, rich in fat and glycogen, and pale in cytoplasm
Imaging performance
1.CT
On plain scan, a well-defined, round, isointense or hypointense mass with some hemorrhage and fatty components, and a few calcifications.
Enhancement
Arterial phase, heterogeneous high density enhancement
Portal phase, relatively uniform density, can be high, equal or low density.
Delayed phase, homogeneous low density.
Sometimes delayed enhancement of the envelope is seen.
2.mr performance
t1wi: signal intensity is not uniform
Signal intensity increase – fat or recent bleeding
Decreased signal intensity – necrosis, calcification or old hemorrhage
t2wi: signal intensity is not uniform
Increased signal intensity – old hemorrhage or necrosis
Decreased signal intensity – fat or recent hemorrhage
Enhanced mr
gd-dtpa – similar to ct enhancement
Superparamagnetic iron oxide – adenoma does not uptake
V. Imaging performance of atypical hemangioma
(A) Atypical hemangioma and its accompanying lesions
1. Atypical hemangioma.
Large, heterogeneous hemangiomas.
Contrast-filled hemangiomas with rapid filling.
Calcified hemangioma.
glassy hemangioma.
angiomas accompanied by fluid-fluid planes.
Exophytic hemangiomas.
2.Concomitant anomalies.
Arteriovenous fistulas.
Indentation of the envelope.
Angiomas can also occur with localized fatty liver infiltration.
3.Concomitant lesions.
Multiple hemangiomas.
Hepatic adenomatosis.
Atypical hemangiomas also include progressive enlargement of hemangiomas and the appearance of hemangiomas during pregnancy.
(B) Imaging manifestations of atypical hemangioma
1. large, heterogeneous hemangioma – a giant hemangioma, usually larger than 4 cm in diameter.
However, some authors use >6cm or >12cm as the standard.
In the arterial phase (hap), early, nodular, coarse speckled enhancement of the margins is typical. In the portal venous phase (pvp) and the delayed phase, there is centripetal filling, but not complete filling.
2. Rapidly filling hemangioma (rapid filling hemangioma)
Rapidly filling hemangiomas are uncommon, accounting for approximately 16% of all hemangiomas. It is most common in small hemangiomas, especially those less than 1 cm in diameter.
The ct and mr presentation is immediate uniform enhancement.
Differentiation from other tumors with rich blood supply is more difficult, and t2wi is helpful in the differential diagnosis, but liver metastases from islet cell tumors with rich blood supply can also have similar presentation.
Accurate diagnosis relies on delayed-period scans, as delayed-scan hemangiomas persistently intensify, whereas metastases with a rich blood supply do not do so. An additional sign is that the hemangioma is consistent with the aortic density in all enhancement phases.
3. Calcified hemangiomas
Hemangiomas in other parts of the body such as soft tissue, gastrointestinal tract, retroperitoneal cavity retroperitoneum, and mediastinum, also show calcification (phleboliths – a specific sign for the diagnosis of hemangioma). Hepatic hemangiomas are less likely to present with calcification, but are also found clinically.
Calcifications in hepatic hemangiomas occur at the margins or in the center of the lesion and can be multiple punctate calcifications – phleboliths – or large foci of calcification . Some calcified hemangiomas may be less enhanced, especially on CT. The finding of a non-enhancing calcified lesion in the liver does not exclude the possibility of a hemangioma. High signal in non-calcified areas on t2wi suggests the diagnosis of hemangioma.
4. glassy hemangioma hyalinized hemangioma
Some authors believe that vitreous changes represent the end stage of hemangioma degeneration.
The imaging presentation of glassy hemangioma is completely different from that of typical hemangioma. Whereas typical hemangiomas have significant high signal in t2wi, this hemangioma has only a slight high signal in t2wi.
In addition, there is a lack of early enhancement. The mr does not distinguish these hemangiomas from other malignant tumors.
Pathology shows diffuse fibrous tissue formation and occlusion of the vascular lumen of the lesion.
5.Hemangioma with fluid-fluid planes within the tumor
Ultrasound often cannot detect the fluid-fluid plane.
The upper fluid component is serum in non-coagulated state – low density on ct, t1wi with muscle iso-signal, and
The t2wi is clearly high signal.
The lower layer is erythrocytes – high density on ct, higher signal on t1wi than muscle, and mildly high signal on t2wi.
The fluid-fluid plane is not specific for the diagnosis of hemangioma.
Some authors believe that if ctmr can detect fluid-fluid planes, but ultrasound cannot, then it can suggest the diagnosis of hemangioma.
6.Exophytic hemangioma pedunculated hemangioma
Exophytic hemangioma is indeed less common.
They can be asymptomatic, but can cause symptoms due to torsion or infarction. Multiplanar reconstruction can help in the diagnosis.
Intensification is the same as in typical hemangiomas.
7. Hemangiomas with arteriovenous fistulas arteriovenous-portal venous
Arteriovenous fistulas are usually associated with malignant tumors, but can be seen in benign tumors as well. The manifestation is early enhancement of the arterial stage lesion accompanied by early portal venous manifestation.
8. hemangioma with capsular retraction
Hemangioma with capsular retraction is usually seen in malignant tumors such as cholangiocytoma, hemangioendothelioma and metastases.
Only one case of hemangioma with capsular retraction has been seen.
9.Hemangioma occurring in the background of fatty liver
On plain scan CT, the lesion can be denser than the adjacent liver or no clear lesion can be seen. Contrast enhancement shows the typical enhancement of hemangioma. It is important to note that in the arterial phase, the hemangioma can appear as isointense. In this case, mr is more helpful.
10. Multiple hemangiomas
10% of hemangiomas are multiple. Multiple hemangiomas with scattered distribution in the liver have a typical presentation. t2wi shows multiple high signal lesions in the liver.
11.Hemangiomatosis hemangiomatosis
The borders of hemangiomas, even giant ones, are clear. However, there are rare cases with large and poorly defined lesions that replace most of the liver parenchyma. It is common in young children, accompanied by heart failure, and has a high mortality rate.
Angiomatosis in adults is often asymptomatic. no typical presentation on ct, but delayed scans can suggest a diagnosis. mr has a more typical presentation.
12. Coexistence of hemangioma and fnh
The coexistence of hemangioma with fnh is more common, with a 23% chance.
It is now believed that coexistence does not occur by chance. In cases of multiple fnh, coexisting hemangiomas are more common, with 33% of multiple fnh being associated with hemangiomas.
It is now believed that fnh is a proliferative response due to increased local arterial blood flow to the liver and therefore fnh resembles hemangioma, both of vascular origin.
The incidence of coexisting hemangioma and fnh in young women taking oral contraceptives is 100%
13. Progressive enlargement of hemangioma enlarging over time
Most hemangiomas remain constant in size or increase minimally with time.
Progressive enlargement of hemangioma has been reported in the literature: one case in pregnancy and two cases in patients with estrogen application. The imaging presentation is the same as that of a typical hemangioma.
The mechanism of progressive enlargement may be due to vascular ectasia, and estrogen administration may also play a role, but this has not been confirmed.
The presence of hemangiomas during pregnancy has also been reported in the literature – also confirming the association of hemangiomas with estrogen.
VI. Hepatic angiomyolipoma (hepatic smooth muscle lipoma)
Hepatic angiomyolipoma is a rare benign tumor. It is composed of different levels of adipose tissue, smooth muscle and abnormal blood vessels, and has certain characteristic imaging manifestations.
Vascular smooth muscle lipoma of the liver can be associated with vascular smooth muscle lipoma of the kidney.
Aml in the kidney is associated with nodular sclerosis in 20% of patients.
Six percent of patients with aml of the liver have nodular sclerosis.
On imaging, a qualitative diagnosis of hepatic vascular smooth muscle lipoma can be made preoperatively because of the fat content, but the imaging presentation varies depending on the ratio of fat, smooth muscle and abnormal blood vessels contained in the tumor.
Pathological features
Gross pathology usually shows a spherical, soft, yellowish or grayish mass with focal hemorrhagic necrosis, mostly without envelope.
On light microscopy, a typical vascular smooth muscle lipoma consists of abnormally thick-walled vessels, smooth muscle cells, and mature adipose tissue, and may be accompanied by extramedullary hematopoietic tissue. The smooth muscle cells may be spindle-shaped or epithelioid, often predominantly epithelioid, polygonal, with abundant cytoplasm, reddish or transparent, and sometimes containing pigment granules. The nuclei may show significant heterogeneity, and multinucleated giant cells with distinct nucleoli are seen. The tumor cells may be distributed in patches or clusters or form beam cords with blood sinuses separating them. Polymorphic epithelial smooth muscle cells are a difficult pathological diagnosis and are often misdiagnosed as hepatocellular carcinoma or adenocarcinoma.
Depending on the fat content of the tumor, there are four types
Mixed type (mixed)
Lipomatous type (lipomatous ≥ 70% fat)
myomatous (myomatous ≤10% fat)
Angiomatous type (angiomatous)
Imaging performance
The imaging features of hepatic vascular smooth muscle lipoma mainly depend on the content of fat in the tumor and the proportion of abnormal blood vessels.
The presence of fat within the tumor is one of the characteristic features of hepatic angiomyolipoma.
The three components of hepatic vascular smooth muscle lipoma can be clearly distinguished in some tumors. Usually, when the fat content is slightly higher, the imaging can show its features. Vascular smooth muscle lipomas that are predominantly fatty (lipomatous) should be distinguished from lipomas or liposarcomas. When the predominantly abnormal vessels are present, there are some similarities with hepatic hemangioma. 50% of hepatic vascular smooth muscle lipomas have no characteristic imaging features due to the lack of fat. In the absence of this feature, CT dynamic enhancement scans can be of great value for diagnosis.
Hepatic vascular smooth muscle lipoma is easily misdiagnosed and should be differentiated from other fat-containing lesions in the liver myxoma tumors.