1. Brief medical history: The patient, female, 51 years old, was treated with surgery for rectal cancer outside the hospital 5 months ago. Pre-operative examination revealed multiple parenchymal occupations in the liver, and chemotherapy was administered once before surgery and four times after surgery. There was no fever, abdominal distension, abdominal pain, nausea or vomiting during the course of the disease. Previous history of hepatitis B and diabetes mellitus was denied. There was no history of specific occupational exposure and no family history of hereditary disease. 2. Physical examination: The patient was clear, in an autonomous position, and cooperative in physical examination. Blood pressure was 120/80 mmHg, body temperature was 37℃, respiration was 20 times/minute, pulse was 80 times/minute. There was no yellow staining of skin and sclera, no liver palm or spider nevus. No superficial enlarged lymph nodes were found. Bilateral pupils are equal in size and round, no jugular venous anger, trachea is in the center, heart rate is uniform, no abnormal murmur. The respiratory movements of both lungs were symmetrical, the voice tremor was normal, and there was no dry or wet woven grass.8 The patient’s blood count, liver and kidney function, urinary routine and fecal routine were normal. The hepatitis B two-to-one half was negative. Tumor markers AFP was in the normal range, CEA and CA199 were significantly elevated (AFP 5.7 ng/ml, CEA 48.94 ng/ml, CA199 >10000 U/ml). 4, imaging: T1-weighted MRI revealed multiple low-signal parenchymal occupying lesions in the liver with a round-like morphology and clear borders, in addition to multiple lower-signal occupancies in the liver; T2-weighted multiple high-signal occupancies in the liver, in addition to multiple higher-signal occupancies; plain scan revealed multiple low-signal occupancies in the liver, in which multiple lower-signal occupancies were seen; arterial phase revealed significant peri-focal enhancement, intra-focal In the arterial phase, there is no enhancement, and there is no enhancement of multiple lower signal occupancies; in the venous phase, there is slightly weaker enhancement around the lesion than in the arterial phase, and there is slightly more enhancement inside the lesion than in the arterial phase, and there is no significant change of lower signal occupancies. 5.Question: Please consider the diagnosis and differential diagnosis based on the above information? 6.Answer: Metastatic hepatocellular carcinoma with multiple cysts in the liver Based on the MRI findings and its enhancing characteristic manifestations, combined with the medical history, metastatic hepatocellular carcinoma with multiple cysts in the liver should be considered. Postoperative pathology confirmed metastatic hepatocellular carcinoma. 7 .Discussion Metastatic liver cancer, also known as secondary liver cancer, is one of the more common malignant tumors in clinical practice. Due to the rich blood supply to the liver, all malignant tumors in the human body can metastasize to the liver with blood and lymphatic fluid, or directly infiltrate to form secondary liver cancer. Metastatic liver cancer is most often secondary to gastrointestinal tumors, such as colorectal cancer and gastric cancer. Secondary to lung cancer, pancreatic cancer, breast cancer, etc. are also common. The clinical manifestations of secondary liver cancer are generally based on the manifestations and symptoms of primary organ cancer. Patients may have weakness, anorexia, excessive sweating, fever, weight loss, etc. Liver function tests are mostly normal, and serum tumor markers related to the primary tumor are often significantly increased. Apart from clinical manifestations and serum tumor marker tests, the diagnosis of metastatic liver cancer mainly relies on imaging diagnosis. CT scan of metastatic hepatocellular carcinoma generally shows multiple scattered nodular hypodense shadows with uniform or inhomogeneous density and clear sharp or indistinct borders. Some lesions are not easily detectable with normal liver parenchyma because the density difference between them and normal liver parenchyma is not large. The performance of enhanced CT scan of metastatic hepatocellular carcinoma is generally related to the degree of vascularity of the tumor, with various performances. 1) Most of the metastatic hepatocellular carcinomas have less blood supply, and the enhancement scan can show circumferential enhancement around the lesion, which is called “bull’s eye” sign or “ring target” sign, which is a typical manifestation of intrahepatic metastases of malignant tumors of digestive system origin. It is a typical manifestation of intrahepatic metastases of malignant tumors of digestive origin. The “bull’s-eye” sign or “ring target” sign is caused by the central hypodensity of the lesion, the edge enhancement, and the outermost density is lower than the liver parenchyma. 2) Metastatic hepatocellular carcinoma from kidney, thyroid, melanoma, carcinoid tumor, sarcoma, etc., are mostly blood-rich lesions with significant enhancement in the arterial phase and basic withdrawal of contrast in the portal vein phase, similar to the CT enhancement scan of primary hepatocellular carcinoma. Therefore, it is difficult to distinguish some single liver metastases from primary liver cancer, and a comprehensive diagnosis is needed in combination with clinical history and relevant tumor markers and other laboratory tests.3) metastases with moderate blood supply may have mild enhancement with inhomogeneous density and poorly defined borders after enhancement; 4) a few metastatic liver cancers become isointense after enhancement, making the detection of lesions difficult. MRI manifestation of metastatic hepatocellular carcinoma is also related to the histological characteristics of the primary tumor; the signal changes on T1W I and T2W I in MRI flat scan are various, with irregular but clear borders, round or oval, multiple or single. The enhancement pattern after enhancement is related to the richness of tumor blood supply, and the performance is similar to that of enhanced CT scan. (1) Hepatocellular hepatocellular carcinoma: Hepatocellular hepatocellular carcinoma is the most common malignant tumor of the liver in China. The lesions are mostly solitary, and the lesions are obviously enhanced in the hepatic artery phase scan, while the density of the lesions decreases in the portal phase and delayed phase scan, showing the characteristic of “fast in and fast out”. In a few cases of hepatocellular carcinoma with less blood supply, the enhancement is not obvious and needs to be differentiated. A clear diagnosis can be made based on the history of hepatitis cirrhosis and AFP elevation, combined with clinical history and physical signs. (2) Cholangiocarcinoma: The tumor is rich in fibrous interstitium, and most of them are poorly defined or clear low density lesions on plain scan, with unremarkable enhancement at the arterial stage, and mild to moderate enhancement at the margins, and delayed enhancement at the venous stage and delayed stage. Cholangiocarcinoma may be associated with bile duct dilatation and intrahepatic bile duct stones. It is often associated with CA199 elevation. Most of them are single lesions, so they can be differentiated. (3) Liver abscess: there may be fever, right upper abdominal pain, elevated leukocytes and other clinical manifestations, chronic liver abscess is mainly central liquefaction necrosis, surrounded by an intact envelope, with circumferential enhancement and peripheral low-density edema band. The foci may also be multifocal. The lesions may also be multifocal and may be reinforced at their separation. In hepatic abscesses, the circumferential enhancement is more extensive, more pronounced, and of longer duration, and larger lesions tend to have more distinctly intensified compartments, with gas visible in some lesions, and the patient has a clinical history of high fever and liver pain. On T2-weighted images, extensive edema is seen around the acute liver abscess as a large area of higher signal. It can be differentiated. (4) Some metastatic hepatocellular carcinoma lesions show cystic changes on plain scan, which need to be differentiated from hepatic multiple cysts. Cystic metastases have irregular morphology and thicker wall than hepatic multilocular cysts, and mild circumferential enhancement can be seen in enhancement. Larger lesions can be lobulated and incompletely separated, and the separation can be mildly enhanced, while hepatic cysts have regular morphology, thin wall, clear and sharp border, and no enhancement. Accordingly, combined with the medical history and clinical manifestations, it can be differentiated.