Hepatocellular carcinoma (HCC) is one of the major tumors that threaten human health. hepatocellular carcinoma is highly prevalent in southeastern Africa and Southeast Asia, and in China it is mostly seen in the southeast coast. In China, HCC has the 2nd highest mortality rate of malignant tumors. About 110,000 people die from HCC each year, including about 80,000 men and 30,000 women, accounting for 45% of HCC deaths worldwide. The main reason for the unsatisfactory outcome of HCC is the late diagnosis. 70% to 80% of HCC patients are found to be at advanced stage and cannot be effectively treated radically. A large number of clinical data show that the treatment effect of small HCC with a diameter of ≤5 cm is significantly better than that of large HCC with a diameter of >5 cm, in which micro HCC with a diameter of ≤2 cm is more effective. Therefore, early diagnosis of HCC is especially important. Enhancing the awareness of cancer prevention among HCC risk groups, establishing a perfect screening system, and using various tests to improve the detection rate of small HCC are of great importance in improving the therapeutic effect of HCC, prolonging patients’ survival and ensuring their survival quality. Factors affecting the early diagnosis of HCC at this stage in China It is still difficult to significantly improve the level of early breakage of HCC. One of them is the non-technical factors, i.e., the lack of awareness of the risk group to actively seek medical consultation or regular medical checkups; the insufficient education and management of the risk group of HCC by medical workers. The second is the technical factors, such as the rare benign occupations in the liver have the characteristics of small lesions and negative AFP, which are difficult to distinguish from small HCC; the “non-occupying” AFP is elevated; multiple imaging methods have their own advantages and shortcomings, and experience is needed to optimize the combination of various tests to improve the diagnosis rate. Several important tasks for early diagnosis 1. Establish HCC early screening clinic and HCC risk group database The most important measure for early diagnosis is scientific and effective screening. According to the risk level of HCC, the HCC-prone population is generally divided into three categories: the first is the high-risk group, such as patients who develop cirrhosis due to chronic viral hepatitis (hepatitis B or C); the second is the moderate-risk group, such as patients with chronic viral hepatitis but without family history of cirrhosis and HCC; the third is the low-risk group, such as patients with non-viral causes of cirrhosis. Different examinations are performed according to the three categories. Generally, the high-risk group should have relevant examinations (liver function, methemoglobin and ultrasound) every 3 months; the medium-risk group should have examinations at least every 6 months; the low-risk group should have relevant examinations every 1 year. When a suspicious case is detected, it should be further ranked according to the HCC early diagnosis process until the HCC diagnosis is clear. Our department has carried out HCC early screening clinic. We collect case data of HCC risk group, establish a database of HCC risk group patients, and classify and manage the group in the database according to the risk level of having HCC, so that each patient in the database can be followed up regularly to screen for HCC, and strive to make the work focus forward so that HCC can be both diagnosed and effectively treated at the stage of small HCC, which is in line with the national development strategy for major diseases such as tumor development strategy. Both the early screening clinic and the HCC risk group database are run by our regular physicians. Through the comprehensive work of health education, chronic liver disease health care, doctor-patient interaction, data management, regular HCC screening and follow-up for the HCC risk group, we can prevent the occurrence and development of portal hypertension to the greatest extent, prevent the occurrence of HCC, improve the diagnosis rate of early HCC, broaden the application space of minimally invasive treatment, which can not only significantly improve the efficacy of HCC, but also shorten the treatment time and reduce the treatment cost. It has good economic and social benefits and potential promotion value. 2. Standardize the process of early diagnosis of HCC Liver nodules of <1 cm found by ultrasound screening should be followed up every 1 month. If the nodules do not increase in size after 2 years of follow-up, they should be routinely examined every 3 months. For liver nodules of 1 to 2 cm detected by ultrasound screening, any two imaging tests, including ultrasonography, enhanced CT or enhanced MRI, should be performed to further clarify the diagnosis. If both examinations have typical HCC features (fast in and fast out), the diagnosis of HCC is definitive and treatment is given accordingly. If there is a lack of characteristic presentation or inconsistent presentation of blood supply on both imaging examinations, further puncture biopsy is necessary. The first finding of >2 cm nodules and one imaging with typical HCC blood supply presentation or AFP >200 ng/ml can confirm the diagnosis without puncture. If imaging does not show characteristic blood supply or if there is no background of cirrhosis, puncture is necessary to clarify the diagnosis. Puncture specimens of small nodules should be judged by an experienced pathologist. If the diagnosis of HCC is not supported, the patient should undergo ultrasonography or CT every 3 to 6 months until the lesion disappears, enlarges, or shows characteristic manifestations of HCC. If the nodule increases in size but still does not show typical signs of HCC, a repeat puncture biopsy is recommended. AFP elevation “without occupancy” should be ruled out by diagnostic procedures of CT, MRI and hepatic arteriography. If intrahepatic occupancy is still not seen, close follow-up should be performed, and once an occupying lesion is present, the diagnosis is established. 3, the value of imaging diagnosis of HCC and evaluation ultrasound ultrasound as a simple, non-invasive and repeatable means of examination, has great value in the diagnosis of HCC. It can be ranked as the first choice, and the confirmation rate of HCC is more than 90%. The main shortcoming of ultrasound imaging is that the lesions on the diaphragmatic surface of the right lobe of the liver and the hilar region are easily missed. The diagnostic accuracy and sensitivity depend largely on the experience of the examiner and the sensitivity of the instrument. Scanning and ultrasound scanning are non-invasive methods with clear images and high resolution, which can show the whole picture of HCC and the invasion of adjacent tissues. The minimum diameter of HCC detected by CT is about 1 cm, and the diagnostic accuracy is between 77.3% and 94.7%. Iodine oil CT (CT + hepatic artery angiography) can further improve the diagnostic sensitivity and detect cancer foci as small as 0.3 cm in diameter. the shortcoming of CT diagnosis of HCC is that diffuse HCC and isointense lesions are easily missed. Tumors in the left lobe of the liver can be misdiagnosed due to artifacts produced by gas in the stomach. The interpretation of images is influenced by the experience of the examiner. The diagnostic value for HCC is similar to that of CT, showing internal tumor structures and daughter tumors and tumor emboli. It is also useful for the identification of HCC nodules, which is superior to other diagnoses than hepatic arteriography. In addition, MRI can provide further information to differentiate metastatic HCC, hemangioma and malformation tumors. Hepatic arteriography is currently the most sensitive diagnostic imaging method for HCC, with a success rate of more than 90% and a diagnostic accuracy of 88% to 93%. The diagnostic value of hepatic arteriography depends on whether the HCC is multivessel or not. If it is oligovascular, it cannot be distinguished from cholangiocarcinoma, and the left lobe of the liver can be falsely negative. Hepatic arteriography is an invasive test with the risk of complications such as bleeding and embolism, and some experience is required to achieve highly selective imaging. PET can clearly show the increased uptake of FDG in cross-sectional, coronal and sagittal positions, which is the principle of PET imaging and applied oncology. 18 F-FDG PET-CT is a fusion of PET and CT, which can obtain rich functional information of molecular metabolism and understand the anatomical localization of tumor tissue. However, HCC cells have special characteristics for glucose uptake, and the higher concentration of glucose-6-phosphatase in well-differentiated HCC cells can accelerate the metabolic process of 18F-FDG, so the content of 18F-FDG in highly differentiated HCC cells is low, which is not enough to show high metabolic performance, and the PET image is often negative, resulting in false-negative results. Therefore, 18 F-FDG PET-CT has some limitations in the detection of highly differentiated HCC lesions. However, 18 F-FDG PET-CT has significant advantages in detecting extrahepatic metastases. Ultrasound-guided fine needle aspiration cytology Ultrasound-guided fine needle aspiration has the advantage of purposeful needle entry, which can avoid large blood vessels and other organs near the puncture target, such as large tumors with irregular necrotic liquefaction in the center, when it is better to guide and select samples with tissue components to focus on, avoiding false negatives due to degenerative liquefaction. Applying this method, the diagnosis rate of HCC is more than 80%. For early HCC cancer nodules, since ultrasound can accurately show the site, depth and size of cancer nodules, ultrasound-guided fine-needle aspiration biopsy, which can be aspirate cytology, can often obtain the histological diagnostic basis of HCC [5]. 4, Differential diagnosis of common hepatic occupying lesions Hepatic cavernous hemangioma, also known as hepatic hemangioma, is the most common benign tumor of the liver. It has a tendency to grow gradually and has no possibility of malignant transformation. Those larger than 5 cm in size are easily diagnosed. Those with smaller size can be easily confused with small HCC. Both ultrasound and CT have a high diagnostic rate for hepatic hemangioma, and MRI is more accurate for identifying hepatic hemangioma. Hepatic adenoma The incidence of hepatic adenoma is second only to hepatic hemangioma, accounting for about 10% of benign liver tumors. It is now mostly thought to be closely related to oral contraceptive use. The bleeding rate and malignancy rate of hepatic adenoma are 29% and 5%, respectively, so in principle, they should be removed surgically as early as possible. Focal nodular hyperplasia (FNH) occurs in young women, with a male to female ratio of about 1:8. Occasionally there is bleeding and calcification, and there is no tendency for malignancy. CT scan shows hypodense or isodense nodules with a central palsy scar in the form of a stellate hypodense shadow. Enhanced scans show uniformly elevated high density in the arterial phase except for the scar foci. The portal phase and delayed scan show isointense lesions, while the central scar appears delayed enhancement. Combination of multiple imaging studies may improve the diagnostic accuracy. Inflammatory pseudotumor of the liver Inflammatory pseudotumor of the liver is an inflammatory proliferative lesion in the liver characterized by fibrous tissue proliferation and chronic inflammatory cell infiltration. The etiology remains unclear. Infection, immune response, hemorrhagic gangrene of the liver parenchyma, occlusive phlebitis and secondary reaction to intrahepatic bile duct rupture may be associated with it. The underlying pathological changes appear as inflammatory proliferative masses. The lesion is infiltrated by a variety of inflammatory cells, including plasma cells, lymphocytes, eosinophils, and phagocytes. There is loss of hepatic tissue structure and proliferation of fibrous tissue, but the liver is usually not sclerotic. Inflammatory pseudotumor of the liver is a benign disease and can be treated with antimicrobial and nonsteroidal anti-inflammatory drugs and regular review of all relevant indicators. However, most of them are misdiagnosed as malignant tumors of the liver and are surgically removed. Adenomatous hyperplasia of the liver Adenomatous hyperplasia is the gradual formation of tumor-like lesions in hepatocytes on the basis of chronic hepatitis and cirrhosis. Specifically, it is an apparently regenerative nodule that occurs in the context of cirrhosis. Hepatitis virus infection may be an important causative factor. Hepatic adenomatous hyperplasia is often a single nodule with a diameter larger than that of cirrhotic nodules, mostly 1 to 3 cm, occasionally up to 10 cm. Hepatic adenomatous hyperplasia is a precancerous lesion of HCC and is difficult to differentiate from small HCC preoperatively, and treatment attitude should be aggressive. Hepatic cysts are very common. They can be multiple or solitary. Most liver cysts are easily distinguished from HCC, but complex cysts are difficult to distinguish from small HCC with cystic changes. Liver cysts can mostly be observed dynamically, and surgical treatment can be considered when a single cyst is large enough or when multiple cysts affect liver function. We expect that with the strengthening of management and education of HCC risk population, the concept of active prevention and early diagnosis, and the combined application of HCC tumor markers, ultrasound, CT and MRI, the clinical appearance of HCC will be dominated by small HCC in the future, and middle and late stage HCC will gradually become rare.