Upon discovery of a liver tumor, the main issue in the workup is to determine whether the tumor is benign or malignant. Many imaging modalities are used to aid in the diagnosis of malignant liver tumors. For the most common of these, hepatocellular carcinoma (HCC), these include sonography (ultrasound), computed tomography (CT) and magnetic resonance imaging (MRI). When imaging the liver with ultrasound, a mass greater than 2 cm has more than 95% chance of being HCC. The majority of cholangiocarcimas occur in the hilar region of the liver, and often present as bile duct obstruction. If the cause of obstruction is suspected to be malignant, endoscopic retrograde cholangiopancreatography (ERCP), ultrasound, CT, MRI and magnetic resonance cholangiopancreatography (MRCP) are used.

Tumor markers, chemicals sometimes found in the blood of people with cancer, can be helpful in diagnosing and monitoring the course of liver cancers. High levels of alpha-fetoprotein (AFP) in the blood can be found in many cases of HCC and intrahepatic cholangiocarcinoma. Cholangiocarcinoma can be detected with these commonly used tumor markers: carbohydrate antigen 19-9 (CA 19-9), carcinoembryonic antigen (CEA) and cancer antigen 125 (CA125). These tumour markers are found in primary liver cancers, as well as in other cancers and certain other disorders..

Ultrasonography of liver tumors involves two stages: detection and characterization. Tumor detection is based on the performance of the method and should include morphometric information (three axes dimensions, volume) and topographic information (number, location specifying liver segment and lobe/lobes). The specification of these data is important for staging liver tumors and prognosis. Tumor characterization is a complex process based on a sum of criteria leading towards tumor nature definition. Often, other diagnostic procedures, especially interventional ones are no longer necessary. Tumor characterization using the ultrasound method will be based on the following elements: consistency (solid, liquid, mixed), echogenicity, structure appearance (homogeneous or heterogeneous), delineation from adjacent liver parenchyma (capsular, imprecise), elasticity, posterior acoustic enhancement effect, the relation with neighboring organs or structures (displacement, invasion), vasculature (presence and characteristics on Doppler ultrasonography and contrast-enhanced ultrasound (CEUS).

Medical imaging techniques such as X-rays, ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI) are often used in evaluating animals with suspected liver tumors. Ultrasound-guided fine-needle aspiration or needle-core biopsy of liver masses are useful diagnostic tools that are minimally invasive to obtain samples for histopathological analysis.

The most common method of testing for hepatoblastoma is a blood test checking the alpha-fetoprotein level. Alpha-fetoprotein (AFP) is used as a biomarker to help determine the presence of liver cancer in children. At birth, infants have relatively high levels of AFP, which fall to normal adult levels by the first year of life. The normal level for AFP in children has been reported as lower than 50 nanograms per milliliter (ng/ml) and 10 ng/ml. An AFP level greater than 500 (ng/ml) is a significant indicator of hepatoblastoma. AFP is also used as an indicator of treatment success. If treatments are successful in removing the cancer, the AFP level is expected to return to normal.

Surgical treatment is recommended for cats and dogs diagnosed with primary liver tumors but not metastasis to the liver. There are not many treatment options for animals who have multiple liver lobes affected.

HCC remains associated with a high mortality rate, in part related to initial diagnosis commonly at an advanced stage of disease. As with other cancers, outcomes are significanty improved if treatment is initiated earlier in the disease process. Because the vast majority of HCC occurs in people with certain chronic liver diseases, especially those with cirrhosis, liver screening is commonly advocated in this population. Specific screening guidelines continue to evolve over time as evidence of its clinical impact becomes available. In the United States, the most commonly observed guidelines are those published by the American Association for the Study of Liver Diseases (AASLD). The AASLD recommends screening people with cirrhosis with ultrasound every 6 months, with or without measurement of blood levels of tumor marker AFP. Elevated levels of AFP are associated with active HCC disease, although inconsistently reliable. At levels >20 sensitivity is 41-65% and specificity is 80-94%. However, at levels >200 sensitivity is 31, specificity is 99%.

On US, HCC often appears as a small hypoechoic lesion with poorly defined margins and coarse irregular internal echoes. When the tumor grows, it can sometimes appear heterogeneous with fibrosis, fatty change, and calcifications. This heterogeneity can look similar to cirrhosis and the surrounding liver parenchyma. A systematic review found that the sensitivity was 60 percent (95% CI 44-76%) and specificity was 97 percent (95% CI 95-98%) compared with pathologic examination of an explanted or resected liver as the reference standard. The sensitivity increases to 79% with AFP correlation.

There remains controversy as to the most effective screening protocols. For example, while there is data to support decreased mortality related to screening in people with hepatitis B infection, the AASLD notes that “there are no randomized trials [for screening] in Western populations with cirrhosis secondary to chronic hepatitis C or fatty liver disease, and thus there is some controversy surrounding whether surveillance truly leads to a reduction in mortality in this population of patients with cirrhosis.”

In a person where there is higher suspicion of HCC, such as a person with symptoms or abnormal blood tests (i.e. alpha-fetoprotein and des-gamma carboxyprothrombin levels), evaluation requires imaging of the liver by CT or MRI scans. Optimally, these scans are performed with intravenous contrast in multiple phases of hepatic perfusion in order to improve detection and accurate classification of any liver lesions by the interpreting radiologist. Due to the characteristic blood flow pattern of HCC tumors, a specific perfusion pattern of any detected liver lesion may conclusively detect an HCC tumor. Alternatively, the scan may detect an indeterminate lesion and further evaluation may be performed by obtaining a physical sample of the lesion.

Surgical removal of the tumor, adjuvant chemotherapy prior to tumor removal, and liver transplantation have been used to treat these cancers. Primary liver transplantation provides high, long term, disease-free survival rate in the range of 80%, in cases of complete tumor removal and adjuvant chemotherapy survival rates approach 100%. The presence of metastases is the strongest predictor of a poor prognosis.

Many imaging modalities are used to aid in the diagnosis of primary liver cancer. For HCC these include sonography (ultrasound), computed tomography (CT) and magnetic resonance imaging (MRI). When imaging the liver with ultrasound, a mass greater than 2 cm has more than 95% chance of being HCC. The majority of cholangiocarcimas occur in the hilar region of the liver, and often present as bile duct obstruction. If the cause of obstruction is suspected to be malignant, endoscopic retrograde cholangiopancreatography (ERCP), ultrasound, CT, MRI and magnetic resonance cholangiopancreatography (MRCP) are used.

Tumor markers, chemicals sometimes found in the blood of people with cancer, can be helpful in diagnosing and monitoring the course of liver cancers. High levels of alpha-fetoprotein (AFP) in the blood can be found in many cases of HCC and intrahepatic cholangiocarcinoma. Cholangiocarcinoma can be detected with these commonly used tumor markers: carbohydrate antigen 19-9 (CA 19-9), carcinoembryonic antigen (CEA) and cancer antigen 125 (CA125). These tumour markers are found in primary liver cancers, as well as in other cancers and certain other disorders.

Liver haemangiomas are typically hyperechoic on ultrasound though may occasionally be hypoechoic; ultrasound is not diagnostic. Computed tomography (CT), magnetic resonance imaging (MRI) or single-photon emission computed tomography (SPECT) using autologous labelled Red Blood Cells (RBC) with Tc-99m is diagnostic. Biopsy is avoided due to the risk of haemorrhage.

Hepatic haemangiomas can occur as part of a clinical syndrome, for example Klippel-Trenaunay-Weber syndrome, Osler–Weber–Rendu syndrome and Von Hippel-Lindau syndrome.

Treatment can consist of surgery (hepatectomy), chemotherapy and/or therapies specifically aimed at the liver like radiofrequency ablation, transcatheter arterial chemoembolization, selective internal radiation therapy and irreversible electroporation. For most patients no effective treatment exists because both lobes are usually involved, making surgical resection impossible. Younger patients with metastases from colorectal cancer confined to one lobe of the liver and up to 4 in number may be treated by partial hepatectomy. In selected cases, chemotherapy may be given systemically or via hepatic artery.

In some tumors, notably those arising from the colon and rectum, apparently solitary metastases

or metastases to one or other lobes may be resected. A careful search for other metastases is required, including local recurrence of the original primary tumor (e.g., via colonoscopy) and dissemination elsewhere (e.g., via CT of the thorax). 5 year survival rates of 30-40% have been reported following resection.

Prevention of cancers can be separated into primary, secondary, and tertiary prevention. Primary prevention preemptively reduces exposure to a risk factor for liver cancer. One of the most successful primary liver cancer preventions is vaccination against hepatitis B. Vaccination against the hepatitis C virus is currently unavailable. Other forms of primary prevention are aimed at limiting transmission of these viruses by promoting safe injection practices, screening blood donation products, and screening high-risk asymptomatic individuals. Aflatoxin exposure can be avoided by post-harvest intervention to discourage mold, which has been effective in west Africa. Reducing alcohol abuse, obesity, and diabetes would also reduce rates of liver cancer. Diet control in hemochromatosis could decrease the risk of iron overload, decreasing the risk of cancer.

Secondary prevention includes both cure of the agent involved in the formation of cancer (carcinogenesis) and the prevention of carcinogenesis if this is not possible. Cure of virus-infected individuals is not possible, but treatment with antiviral drugs such as interferon can decrease the risk of liver cancer. Chlorophyllin may have potential in reducing the effects of aflatoxin.

Tertiary prevention includes treatments to prevent the recurrence of liver cancer. These include the use of chemotherapy drugs and antiviral drugs.

Hemangiosarcoma can cause a wide variety of hematologic and hemostatic abnormalities, including anemia, thrombocytopenia (low platelet count), disseminated intravascular coagulation (DIC); presence of nRBC, schistocytes, and acanthocytes in the blood smear; and leukocytosis with neutrophilia, left shift, and monocytosis.

A definitive diagnosis requires biopsy and histopathology. Cytologic aspirates are usually not recommended, as the accuracy rate for a positive diagnosis of malignant splenic disease is approximately 50%. This is because of frequent blood contamination and poor exfoliation. Surgical biopsy is the typical approach in veterinary medicine.

A cavernous liver haemangioma or hepatic haemangioma is a benign tumour of the liver composed of hepatic endothelial cells. It is the most common liver tumour, and is usually asymptomatic and diagnosed incidentally on radiological imaging. Liver haemangiomas are thought to be congenital in origin. Several subtypes exist, including the giant hepatic haemangioma, which can cause significant complications.

Ultrasound is routinely used in the evaluation of cirrhosis. It may show a small and nodular liver in advanced cirrhosis along with increased echogenicity with irregular appearing areas. Other liver findings suggestive of cirrhosis in imaging are an enlarged caudate lobe, widening of the fissures and enlargement of the spleen. An enlarged spleen (splenomegaly), which normally measures less than 11–12 cm in adults, is suggestive of cirrhosis with portal hypertension, in the right clinical context. Ultrasound may also screen for hepatocellular carcinoma, portal hypertension, and Budd-Chiari syndrome (by assessing flow in the hepatic vein).

Cirrhosis is diagnosed with a variety of elastography techniques. Because a cirrhotic liver is generally stiffer than a healthy one, imaging the liver's stiffness can give diagnostic information about the location and severity of cirrhosis. Techniques used include transient elastography, acoustic radiation force impulse imaging, supersonic shear imaging and magnetic resonance elastography. Compared to a biopsy, elastography can sample a much larger area and is painless. It shows a reasonable correlation with the severity of cirrhosis.

Other tests performed in particular circumstances include abdominal CT and liver/bile duct MRI (MRCP).

A liver metastasis is a malignant tumor in the liver that has spread from another organ affected by cancer. The liver is a common site for metastatic disease because of its rich, dual blood supply (the liver receives blood via the hepatic artery and portal vein). Metastatic tumors in the liver are 20 times more common than primary tumors. In 50% of all cases the primary tumor is of the gastrointestinal tract, other common sites include the breast, ovaries, bronchus and kidney.

Tumor emboli entering the sinusoids through the liver blood supply appear to be physically obstructed by the Kupffer cells, but if tumor emboli are larger, they tend to become lodged in the portal venous branches.

Blood tests should be done, importantly liver-function series, which will give a good impression of the patient's broad metabolic picture.

A complete blood test can help distinguish intrinsic liver disease from extrahepatic bile-duct obstruction. An ultrasound of the liver can reliably detect a dilated biliary-duct system,

it can also detect the characteristics of a cirrhotic liver.Computerized tomography (CT) can help to obtain accurate anatomical information, in individuals with hepatomegaly.

Chronic liver disease takes several years to develop and the condition may not be recognised unless there is clinical awareness of subtle signs and investigation of abnormal liver function tests.

Testing for chronic liver disease involves blood tests, imaging including ultrasound and a biopsy of the liver. The liver biopsy is a simple procedure done with a fine thin needle under local anaesthesia. The tissue sample is sent to a laboratory where it is examined underneath a microscope.

Gastroscopy (endoscopic examination of the esophagus, stomach, and duodenum) is performed in patients with established cirrhosis to exclude the possibility of esophageal varices. If these are found, prophylactic local therapy may be applied (sclerotherapy or banding) and beta blocker treatment may be commenced.

Rarely are diseases of the bile ducts, such as primary sclerosing cholangitis, causes of cirrhosis. Imaging of the bile ducts, such as ERCP or MRCP (MRI of biliary tract and pancreas) may aid in the diagnosis.

The management of PASH is controversial. Excision may be indicated in enlarging masses or lesions with atypical features.

Most individuals are asymptomatic and are usually discovered incidentally because of abnormal liver function tests or hepatomegaly noted in unrelated medical conditions. Elevated liver biochemistry is found in 50% of patients with simple steatosis. The serum alanine transaminase level usually is greater than the aspartate transaminase level in the nonalcoholic variant and the opposite in alcoholic FLD (AST:ALT more than 2:1).

Imaging studies are often obtained during the evaluation process. Ultrasonography reveals a "bright" liver with increased echogenicity. Medical imaging can aid in diagnosis of fatty liver; fatty livers have lower density than spleens on computed tomography (CT), and fat appears bright in T1-weighted magnetic resonance images (MRIs). No medical imagery, however, is able to distinguish simple steatosis from advanced NASH. Histological diagnosis by liver biopsy is sought when assessment of severity is indicated.

A number of liver function tests (LFTs) are available to test the proper function of the liver. These test for the presence of enzymes in blood that are normally most abundant in liver tissue, metabolites or products. serum proteins, serum albumin, serum globulin,

alanine transaminase, aspartate transaminase, prothrombin time, partial thromboplastin time.

Imaging tests such as transient elastography, ultrasound and magnetic resonance imaging can be used to examine the liver tissue and the bile ducts. Liver biopsy can be performed to examine liver tissue to distinguish between various conditions; tests such as elastography may reduce the need for biopsy in some situations.

Treatment is varied and depends on the site and extent of tumor involvement, site(s) of metastasis, and specific individual factors. Surgical resection, radiotherapy, and chemotherapy have all been used to treat these masses, although studies on survival have yet to be conducted to delineate various treatment regimens.

The diagnosis of PASH is by biopsy.

The important differential diagnosis is angiosarcoma, from which it was first differentiated in 1986.

This remains a challenge in clinical practice due to a lack of reliable markers. Many other conditions lead to similar clinical as well as pathological pictures. To diagnose hepatotoxicity, a causal relationship between the use of the toxin or drug and subsequent liver damage has to be established, but might be difficult, especially when idiosyncratic reaction is suspected. Simultaneous use of multiple drugs may add to the complexity. As in acetaminophen toxicity, well established, dose-dependent, pharmacological hepatotoxicity is easier to spot. Several clinical scales such as CIOMS/RUCAM scale and Maria and Victorino criteria have been proposed to establish causal relationship between offending drug and liver damage. CIOMS/RUCAM scale involves a scoring system that categorizes the suspicion into "definite or highly probable" (score > 8), “probable” (score 6-8), “possible” (score 3-5), “unlikely” (score 1-2) and “excluded” (score ≤ 0). In clinical practice, physicians put more emphasis on the presence or absence of similarity between the biochemical profile of the patient and known biochemical profile of the suspected toxicity (e.g., cholestatic damage in amoxycillin-clauvonic acid ).